CaCO3 slurry

One of the idiots responsible for cloudy water

I started experimenting with this method when I noticed that I couldn’t keep the water clear with conventional mechanical filtration. I have four Pomacentrus simils that keep digging the sand bed and are constantly introducing small particles into the water column. I was using a traditional setup of a powerful powerhead and some filtration mat but I clearly needed something more efficient.

I had used very fine home made aragonite (CaCO3) powder over the years whenever I thought the water could use some “polishing” and it worked very well. So this time I was going to do the same but together with mechanical filtration which would trap most of the particles and thus create much more efficient filtration media. Fresh CaCO3 surface is an excellent binder of dissolved organic matter (DOM) and is also known to bind phosphate so those were an added bonus.

It quickly turned out that the enhancing mechanical filtration part of my idea was not working so great – the rate at which the fish add particles is just too fast for any filter to keep up with (unless I add the filter into the display tank itself which I certainly do not want to do). Instead I noticed much improved water clarity and  less yellow coloration. So much so that I completely removed the activated carbon (GAC) filtration I had used for years. To my surprise, daily additions of CaCO3 slurry was able to keep water very clean even without the help of GAC. I did eventually add some carbon back to filtration because my feeding experiments but still the performance of aragonite powder was surprising to me.

I think this method is something more adventurous reef aquarium owners might want to experiment with. Producing your own CaCO3 slurry is very easy and much, much less expensive than buying the same stuff in those nice little blue bottles.

1. Mix together 2:2:1 calcium chloride, sodium bicarbonate and calcium hydroxide. BE SURE TO WEAR MASK OR OTHER PROTECTION. DO NOT INHALE THE DUST.
2. Fill large container with hot water
3. Slowly add the mixture, constantly stirring the solution. This will create a lot of carbon dioxide so be careful not to add the mixture too fast or it will overflow.
4. Let it sit so that the precipitate drops to bottom
5. Carefully pour out as much water as you can and refill
6. Go back to 4. Repeat a couple of times. This rinsing is necessary to get the NaCl out of the solution

Sugar

I don’t think there’s much to say about DOC dosing that isn’t well known by all reef aquarists. Sugar (sucrose, a molecule combining glucose and fructose) is just one of the possible sources of organic carbon reef aquarists can use. It is cheap and very pure form of OC.

One thing that I’ve noticed is that DOC also benefits directly certain invertebrates that are able to feed on DOM and/or have symbiotic bacteria. As I have started to use Biopellets (described later) I’ve started to wonder if it is beneficial to continue DOC dosing even if not absolutely necessary for inorganic nutrient reduction. The question is which one is more beneficial, the production of bacterioplankton by Biopellets or the direct feeding of DOC by the symbiotic bacteria in sponges, for example. Naturally dosing of organic carbon in liquid form also has its drawbacks. For example, as the DOC is distributed evenly in the system, bacteria often grow in places you don’t want them to. For example in pipes and hoses, reducing the water flow significantly or on the glasses and other visible surfaces.

I’m currently using a solution of 400 g/l sucrose. Total daily dose is 10 ml split into 8 doses that are added by the dosing pump.

Biopellets

The amount of bacteria produced by Biopellets is simply amazing

A while ago I was reading an interesting article on coralscience.org about filter feeders that mentioned a new, interesting filtration media called Biopellets. This media is a solid form of organic carbon (POC, particulate organic carbon) on which bacteria can grow and multiply.

Using organic carbon in a solid form has many benefits and hardly any drawbacks compared to DOC dosing. First of all it provides essentially a limitless amount of carbon for bacteria to utilize. The only limiting factor is the amount of free surface area. To optimize the performance you should either use the media in a fluidizing filter or disturb the media mechanically every now and then.

Biopellets also solve the problem of bacteria growing in unwanted places by concentrating much of the production inside the filter instead of distributing the organic carbon all over the system. At the same time this can also be a negative thing because of the fact that much of the particulate matter that every captive reef produce in abundance is going to be broken down somewhere else in the system, typically in sand bed and live rock. As it has become more and more evident that much of the nutrient cycling through microbial loop in reef aquariums is limited by the amount of labile organic carbon it seems to me that these processes could benefit from the addition of a carbon source (DOC). One interesting possibility is to add some pellets inside the sand bed. There is a concern about the possible H2S production but it should be remembered that there is a very oxygen rich layer on top of the sand bed that should easily oxidize H2S if it indeed was produced.

Third benefit is convenience. It is much easier to add some pellets every 6 months than it is to dose minute amounts of DOC varieties. Disturbing the pellets inside a media bag is also not a big commitment. Even I can manage to do that.

Tunicates love to eat bacteria produced by Biopellets

To me one of the best features of Biopellets is its ability to produce a huge amount of bacterial biomass which in turn is excellent food for many filter feeders. The bacteria will come off the Biopellets as large aggregates that will be broken down to progressively smaller clumps of bacteria by the pumps. Bacteria aggregates are the most important food source for many difficult to keep invertebrates like bivalves and tunicates. These animals are typically unable to filter out single bacteria (they are called crude filterers) but when they are clumped together like in nature they are filtered out extremely effectively. Fine filterers like sponges and some polychaetes are also able to eat these particles in addition to single bacteria cells. Any bacteria left uneaten will be removed by protein skimmer or they will populate other aquarium surfaces and continue their work there.

All in all I’m very impressed by this new method of providing more natural environment for reef creatures. I’m especially thankful that there still exists people and companies who are able to innovate instead of copying. Why is it that many times it is the individuals or small companies like Reef Interests that come up with new exiting ideas? Most of the larger aquarium companies seem to only copy the same 30 additives and equipment that everyone else is producing. It is then left at marketing to try to differentiate the products from the rest and everyone knows what the marketing department produces. There are many companies with absolutely no original product ideas.

I’m sure the less capable companies will soon try to copy Biopellets but I think we hobbyists should try to support companies like Reef Interests as much as we can so that the art of reefkeeping moves forward.

Biopellets is made by Reef Interests and should be available in EU stores soon.

The cone: “Medium” from Aquarium Technik Burian (ATB)

ATB skimmers can be completely taken apart for cleaning

I finally got my new skimmer, model “Medium” from Aquarium Technik Burian (ATB). This is the first “high end” piece of equipment I’ve ever owned and I’m glad I did spend almost all my savings on this excellent foam fractionator. It is my opinion that most of the time the “high end” just means “more expensive” without any real benefit but in this case I was paying not only for the best performance in it’s class but also for a legendary customer service and support.

I’m so tired of the modern way of doing business where you must fight every step with companies when you try to solve problems or even to actually get your purchase you’ve paid for. Many times you just don’t get any help. This was once again my experience with ATI when I tried to find out what options I had to replace a pump that had just died on my ATI Bubble Master. This is the original model (without any number after the name) that used single, hand modified version of Eheim 1262 pump. The only source for this special pump would be ATI but the reply I got was “we did not produce the BM with the Eheim pump since a long time.” Well, great! Obviously I was going to change to other manufacturer that wouldn’t leave me with perfectly good skimmer body but no pump.

Anyways, enough ranting, let’s move to more positive things. First of all the performance of this modest sized skimmer is absolutely fantastic. I would say it removes at least twice as much organics compared to ATI Bubble Master 250. It is also very quiet and (needless to say) the fit and finish are first class.

Unlike some of the other skimmers I’ve owned, ATB doesn’t seem to be sensitive to small disturbances like placing your hand in aquarium. Naturally it will temporarily stop foaming if you add oils in some form into the aquarium but it is extremely fast to recover. Besides the raw performance, this must be one of the best features of the ATB conical skimmer. I feed invertebrates 4 times a day, about 30 minutes per feeding. The faster the skimmer can start to reduce the introduced organics after each feeding session the better. Previously, with the ATI skimmer, it would take anything up to one hour before the skimmer would start to skim again but with ATB Medium the time is measured in minutes. It is kind of strange to see skimmer to start producing foam that really shouldn’t “stick” and yet it shoots this mixture of oils and other such stuff into the collection cup in just a few minutes and then proceeds like nothing had happened except that the removal rate is much faster in the first 10-20 minutes after feeding. It is also very easy to monitor the performance of the skimmer because it has a drain; you can count the drip rate. At my setting the drip rate after feeding is 2 per second and as the water gets cleaner and cleaner it settles around one per 3 seconds.

I can sincerely recommend this protein skimmer for tanks around 200 gallons and larger. Be sure to check out ATB’s “econo” line also, I think you get mostly the same benefits at lower price. If the conical shape is responsible for the short recovery time after feeding like I suspect it is you might want to consider a cone as your next skimmer.

I think my tank is now ready for some new interesting animals from Mrutzek Meeresaquaristik scheduled to arrive this thursday

Related posts:

1. New ideas for reef aquarium filtration
2. NP-Biopellets, the story so far
3. Sometimes half full is more than full

Sometimes we hobbyists can’t see the forest from the trees when we discuss and worry about the fine details about reef aquariums. It might be useful to remember why we spend so much time trying to find that optimal protein skimmer or argue about the merits of different additives: the ultimate goal of almost all our actions is to create and maintain water with dissolved salts and organics that resembles as much as possible natural sea water (NSW).

Sometimes it seems to me that even experts who publish articles about marine aquariums get confused about the actual composition of seawater. For example, there is a lot talk about iron (Fe) even though it is one of the least concentrated elements – no one seems to care that there is 320 times more barium in seawater. Barium concentration follows so called “nutrient profile” meaning it’s concentration is typically controlled by biological processes so it should be of interest for aquarists. The natural concentration of iron for surface water would be around 0,0000006 grams per liter. For a 400 liter (100 gallon) tank it means that you can bring the water from zero to NSW levels with just 2,2 µgrams (0,000022 grams) of iron!

Some important notes:

• I use the actual amounts, not the weights! Aquarists use almost exclusively weight as a measure of element concentrations which is not very logical. Actually, it’s just plain wrong! For example, there is about 5x more magnesium than calcium in seawater (52.83 vs. 10.28 mM) and yet I’m sure many people tend to think it’s more like 3x (1200 mg vs 400 mg). The reason for this is that magnesium is much lighter than calcium. For salts in solution the weight of atoms of some elements is really a kind of backwards way to express their amounts. For some less abundant elements this distinction can make a large difference in relative portions of elements
• However, to make it more easy to understand the relative amounts of different groups I have calculated the sum of weights of each group which is displayed on top of the graph. The unit is micrograms (0.001 mg or 0.000001 g) per one kilogram of seawater
• Every successive graph in each section contains elements that combined represent so small amount of total that they don’t even register on the previous graph
• Data does not contain gases
• For elements that have “surface depleted” or “nutrient” distribution profile in seawater I have chosen the low point of concentration range. Typically tabulated data about seawater composition use mean values for elements but since almost all seawater is very deep and very cold the mean value might not be the best representative for waters over corals reefs
• I have excluded Na and Cl (which combined is table salt) because they would dominate all groups they belong to. I assume you know that seawater is almost completely made of water and what little is left is almost completely made of table salt
• If you want the data I’ve compiled, please leave a comment and I will send it to you.
• I wouldn’t be surprised if there are some errors

Everything

Seawater must contain all elements that are found on Earth although not all of them have been detected there yet. Typically seawater is split into two parts, the major and minor (including trace metals) constituents. A common lower limit chosen for major elements is 1 ppm (1 mg/kg). Substances at this and larger concentration can have detectable influence on the density and are usually found in nearly constant proportions to each other and to the salinity. For this reason they are called conservative elements. Most elements present in concentrations of less than 1 ppm are not conservative.

It is quite difficult to present the constituents of the seawater visually because the range of concentrations span several orders of magnitude and yet some very minor element can be as important (or even more important) as the major components, at least from the aquarist’s point of view.  This is the reason why I have chosen the percentage scale and have split the elements so that each pillar shows elements whose combined concentrations would not even register in a previous one. It would be possible to combine all of them in one graph but it would have to be very tall pillar…

An interesting factoid: it is not possible to accurately measure sodium in seawater and thus it’s concentration is determined by summing up equivalent concentrations of all the anions and then subtracting the equivalent concentrations of all the cations except sodium. In theory this means that if it is found that the accepted concentration of some major element should be changed it would also change the reported concentration of sodium. It highly unlikely that there will be a large change to any of the major elements’ concentrations, however.

Note that all chemical elements in the first two pillars are conservative.

This is a group of elements that really define what seawater is. All elements in the piecharts above are always found in those proportions, no matter where in world you are. Their total amount is defined only by salinity and local processes do not alter their concentrations in a significant amounts in  “normal” conditions. This is the reason they are called “conservative elements”. Note: I have listed carbon as a conservative element which it technically isn’t because CO2 concentration can be highly variable.

This also means that by measuring only one parameter you’ll get a very good estimate what the concentration of any other conservative element is. And since the salinity is the only variable affecting the absolute concentrations, you really only need to measure salinity to get, for example, potassium concentration.

The relative proportions of conservative elements is also the ultimate guideline for artificial seawater (ASW) and should in my opinion be the standard that ASW mixes are compared to. Unfortunately, there are only a few mixes that come close. If you are creating a salt mix that is supposed to mimic seawater, you better get at least the elements from the first three piecharts balanced correctly. I just can’t understand how someone can formulate a mix that results in 120% magnesium and 140% calcium concentration and still call it “artificial seawater”. It is saltwater but not even close to seawater.

Follow the nutrients

This is a group of elements that should be most interesting to marine aquarists. All these elements have a distribution model called “nutrient-like distribution” in nature which does not mean they are necessarily considered to be essential nutrients. Instead, “nutrient-like” means that their concentrations follow either one or more of the elements classically labeled as nutrients, namely nitrogen, phosphorous and silicon.

The uptake and release of these elements by biota is large and fast enough to have measurable effect and the effect is so large that the water exchange is not fast enough to either replace or dilute local concentration. These elements are all likely to be incorporated into body materials and transported downwards and then released back when the organic matter is metabolically destroyed.

It is likely that some of these elements will become depleted in a well working reef aquarium with an efficient organic matter removal equipment.

Poor surface

This class of elements are known to be depleted at surface. There can be many reasons for this and for some elements nobody really knows why they are depleted. Some are well known to have important role in biology, like iron and vanadium for example. They do not follow the previous nutrient-like distribution model however because they are not necessarily released back to water column when an organism is broken down but are precipitated and buried into sediments, for example.

One common process that causes the surface depletion is some elements’ tendency to stick to particles and thus be swept out of water column in all depths.

In a reef aquarium these elements are exported together with organisms or particles. If you use efficient mechanical filtration or your skimmer is able to remove particulate matter, it is possible that at least some of these become depleted.

Related posts:

1. Water au naturel
2. ULNS is not really L and far from UL
3. Amino acids and reef aquarium: Glutamic acid

• Representatives of 10 phyla removed significant quantities of glycine from solution during an observation period of 16 to 24 hrs (Stephens and Schinske 1961)
• Glycine is not essential nutritional amino acid for prawns (Cowey and Forster 1971)
• Most abundant DFAA in southern California coastal waters (Clark et al 1972, Carlucci et a 1984)
• Bivalve Mytilus edulis has very high glycine uptake rate (Péquignat 1973, Jørgensen 1983)
• Glycine was not able to elicit feeding response in a stony coral Montastrea cavernosa (Lehman and Porter 1973)
• Glycine evoked opening but not food ingestion in sea anemone Anthopleura midorii (Nagai and Nagai 1973)
• Glycine is found in very large amounts in the skeleton of gorgonians and anthipatharians (Goldberg 1976)
• Many symbiotic bacteria in sponges can utilize glycine (Wilkinson 1978)
• Phytoplankton can use glycine as a sole nitrogen source but only when glycine is present in very large concentration (>2.5 mM) (Berland et al 1979)
• Polychaete Nereis virens is able to use glycine and together with some other amino acids may contribute 7-12% of the metabolism (Jørgensen 1979)
• Uptake by natural heterotrophic bacterial population was rapid (Iturriaga and Zsolnay 1981, Donderski et al 1998)
• Mussel larvae (Mytilus edulis) can effectively compete for glycine with an equivalent biomass of bacteria taken from their natural environment (Manahan and Richardson 1983)
• Together with aspartate most abundant amino acid in fixed carbon pool of light incubated soft coral Capnella gaboensi (Farrant et al 1987)
• One of the most abundant amino acid of shell matrix fraction of bivalve Crassostrea virginica (Wheeler et al 1988)
• Brooded embryos of the ophiuroid Amphipholis squamata, nonfeeding trochophore stage of the annelid Neanthes arenaceodentata and lecithotrophic larvae of the red abalone Haliotis rufescens can feed by taking up glycine directly from seawater (Jaeckle and Manahan 1989)
• Some marine phytoplankton is not able to efficiently utilize glycine (Palenik and Morel 1990)
• Glycine is by far the most abundant amino acid in organic matrix of gorgonian Leptogorgia virgulata (Kingsley et al 1990)
• Ambient concentration in reef waters 2.6 – 43.2 nM (0.000195 – 0.00324 mg/l) (Ferrier 1991). Similar amounts found also by Sommerville and Preston (2001) and Hoeegh-Guldberg and Williamson (1999),
• Glycine is most abundant amino acid in skeleton of Antipathes fiordensis (Cnidaria, Antipatharia) (Goldberg 1991)
• Glycine is easily released from sediments by enzymic activity and might thus be a nutrient source for deposit feeders (Mayer et al 1995)
• Glycine is among the most abundant amino acids in Pocillopora damicornis (Gates et a 1995, see also Bock 2008)
• Part of larval attachment inductor for sedentary polychaetes (Harder and Qian 1999)
• Glycine, together with Asx, is most abundant amino acid in coral reef detritus and algae (Crossman et al 2001, Crossman et al 2005)
• Glycine was one of more abundant components of DCAA in marine sediments and was utilized effectively by anaerobic bacteria (Guldberg et al 2002)
• Glycine is elevated in the organic matrix of hard corals (Ingalls et al 2003, Gupta et al 2006)
• Macroalgae are able to utilize glycine (Tyler et al 2005)
• Glycine is the most successful feeding attractant for post-larval spiny lobster (Williams 2007)
• Uptake rate was relatively slow for Stylophora pistillata (Grover et al 2008)

Berland et al. Concentration Requirement of Glycine as Nitrogen Source for Supporting Effective Growth of Certain Marine Microplanktonic Algae. Mar Biol (1979)

Bock. The Control of Carbon Translocation in a Sea Anemone-dinoflagellate Symbiosis from New Zealand. Victoria University of Wellington (2008)

Carlucci et al. Diel Production and Microheterotrophic Utilization of Dissolved Free Amino Acids in Waters Off Southern California. APPL. ENVIRON. MICROBIOL. (1984)

Clark et al. Dissolved Free Amino Acids in Southern California Coastal Waters. Limnol. Oceanogr. (1972)

Cowey and Forster. The essential amino-acid requirements of the prawn Palaemon serratus. The growth of prawns on diets containing proteins of different amino-acid compositions. Mar Biol (1971)

Crossman et al. Detritus as Food for Grazing Fishes on Coral Reefs. Limnol. Oceanogr (2001)

Crossman et al. Nutritional ecology of nominally herbivorous fishes on coral reefs. Mar Ecol Prog Ser (2005)

Donderski et al. Utilization of Low Molecular Weight Organic Compounds by Marine Neustonic and Planktonic Bacteria. Polish Journal of Environmental Studies (1998)

Farrant et al. Nutrition of the temperate Australian soft coral Capnella gaboensis. Mar Biol (1987)

Ferrier. Net uptake of dissolved free amino acids by four scleractinian corals. Coral Reefs (1991)

Gates et al. Free amino acids exhibit anthozoan “host factor” activity: they induce the release of photosynthate from symbiotic dinoflagellates in vitro. Proc Natl Acad Sci USA (1995) vol. 92 (16) pp. 7430-4

Goldberg. Chemistry and structure of skeletal growth rings in the black coral Antipathes fiordensis (Cnidaria, Antipatharia). Hydrobiologia (1991)

Goldberg. Comparative study of the chemistry and structure of gorgonian and antipatharian coral skeletons. Mar Biol (1976)

Grover et al. Uptake of dissolved free amino acids by the scleractinian coral Stylophora pistillata. J Exp Biol (2008) vol. 211 (Pt 6) pp. 860-5

Guldberg et al. Utilization of Marine Sedimentary Dissolved Organic Nitrogen by Native Anaerobic Bacteria. Limnol. Oceanogr (2002)

Gupta et al. Aspartic acid concentrations in coral skeletons as recorders of past disturbances of metabolic rates. Coral Reefs (2006) vol. 25 (4) pp. 599-606

Harder and Qian. Induction of larval attachment and metamorphosis in the serpulid polychaete Hydroides elegans by dissolved free amino acids: isolation and identification. Mar Ecol Prog Ser (1999)

Hoeegh-Guldberg and Williamson. Availability of two forms of dissolved nitrogen to the coral Pocillopora damicornis and its symbiotic zooxanthellae. Mar Biol (1999)

Ingalls et al. Preservation of organic matter in mound-forming coral skeletons. Geochimica et Cosmochimica Acta (2003)

Iturriaga and Zsolnay. Transformation of some dissolved organic compounds by a natural heterotrophic population. Mar Biol (1981)

Jaeckle and Manahan. Feeding by a “nonfeeding” larva: uptake of dissolved amino acids from seawater by lecithotrophic larvae of the gastropod Haliotis rufescens. Mar Biol (1989)

Jørgensen. Patterns of uptake of dissolved amino acids in mussels (Mytilus edulis). Mar Biol (1983)

Jørgensen. Uptake of L-valine and other amino acids by the polychaete Nereis virens. Mar Biol (1979)

Kingsley et al. Collagen in the spicule organic matrix of the gorgonian Leptogorgia virgulata. Biol Bull (1990) vol. 179 pp. 207-13

Lehman and Porter. Chemical Activation Of Feeding In The Caribbean Reef-Building Coral Montastrea Cavernosa. Biol Bull (1973)

Manahan and Richardson. Competition studies on the uptake of dissolved organic nutrients by bivalve larvae (Mytilus edulis) and marine bacteria. Mar Biol (1983)

Mayer et al. Bioavailable Amino Acids in Sediments: A Biomimetic, Kinetics-Based Approach. Limnol. Oceanogr. (1995)

Nagai and Nagai. Feeding factors for the sea anemone Anthopleura midorii. Mar Biol (1973)

Palenik and Morel. Amino Acid Utilization by Marine Phytoplankton: A Novel Mechanism. Limnol. Oceanogr. (1990)

Péquignat. A Kinetic and Autoradiographic Study of the Direct Assimilation of Amino Acids and Glucose by Organs of the Mussel Mytilus edulis. Mar Biol (1973)

Sommerville and Preston. Characterisation of dissolved combined amino acids in marine waters. Rapid Commun. Mass Spectrom. (2001) vol. 15 (15) pp. 1287-1290

Stephens and Schinske. Uptake of Amino Acids by Marine Invertebrates. Limnol. Oceanogr. (1961)

Tyler et al. Uptake of urea and amino acids by the macroalgae Ulva lactuca (Chlorophyta) and Gracilaria vermiculophylla (Rhodophyta). Mar Ecol Prog Ser (2005)

Wheeler et al. Regulation of in vitro and in vivo CaCO3 crystallization by fractions of oyster shell organic matrix. Mar Biol (1988)

Wilkinson. Microbial associations in sponges. II. Numerical analysis of sponge and water bacterial populations. Mar Biol (1978)

Williams. Feeds development for post-larval spiny lobster: A review. Bull. Fish. Res. Agen. No (2007)

Related posts:

1. Amino acids and reef aquarium: Glutamic acid
2. Amino acids and reef aquarium: Arginine
3. Amino acids and reef aquarium: Aspartic acid

• Glutamic acid was very successful feeding activator for stony coral Montastrea cavernosa, causing full envelopment on every trial (Lehman and Porter 1973)
• One of the predominant amino acids in costal surface water and has high heterotrophic turnover rate (Williams et al 1976)
• Main contributor to the bacterial intracellular amino acid pool, may compete with nitrate uptake (Stanley and Brown 1976)
• Labeled Glutamic acid shows bacterial and not phytoplankton uptake (Hollibaugh 1976)
• Glutamate is an excellent growth media for diatoms (heterotrophic growth) (Lewin and Hellebust 1978)
• Very high uptake by heterotrophic bacteria (75% uptake after 4h) (Iturriaga and Zsolnay 1981, Donderski et al 1998)
• Glutamate is an important part of ammonia assimilation (for example Anderson and Burris 1987 , Catmull et al. 1987, Dudler and Miller 1988, McAuley and Cook 1994, Roberts et al 1999, Teugels et al 2008)
• Glutamic acid concentration in surface (10 cm) water of temperate bay was 3-11 nM (0.00044 – 0.0016 mg/l). Major component of DFAA (Carlucci et al 1991)
• Glutamic acid is thought to be a precursor in synthesis of proline and is present in relatively large amounts in prawn muscle tissue (Smith and Dall 1991)
• Significant amounts of glutamate was present after carbon fixation by isolated zooxanthellae (Streamer et al 1993)
• Glutamic acid is easily released from sediments by enzymic activity and might thus be a nutrient source for deposit feeders (Mayer et al 1995)
• Glutamic acid is the direct precursor of several other amino acids via the tricarboxylic acid cycle, from where, like glucose, its carbon atoms have a high probability of being incorporated into newly synthesized amino acids (Fitzgerald and Szmant 1997)
• Ammonium is assimilated by zooxanthellae into glutamate in Aiptasia pulchella (Swanson and Hoeegh-Guldberg 1998)
• Part of larval attachment inductor for sedentary polychaetes (Harder and Qian 1999)
• Glutamic acid significantly increased bacterial abundance, modified the bacterial community structures on the biofilms, and elevated the inductive effect of the biofilms (Jin and Qian 2005)

Anderson and Burris. Role of glutamine synthetase in ammonia assimilation by symbiotic marine dinoflagellates (zooxanthellae). Mar Biol (1987)

Carlucci et al. Microbial populations in surface films and subsurface waters: Amino acid metabolism and growth. Mar Biol (1991)

Catmull et al. NADP+-dependent glutamate dehydrogenase from Acropora formosa: purification and properties. Mar Biol (1987)

Donderski et al. Utilization of Low Molecular Weight Organic Compounds by Marine Neustonic and Planktonic Bacteria. Polish Journal of Environmental Studies (1998)

Dudler and Miller. Characterization of two glutamate dehydrogenases from the symbiotic microalga Symbiodinium microadriaticum isolated from the coral Acropora formosa. Mar Biol (1988)

Fitzgerald and Szmant. Biosynthesis of ‘essential’ amino acids by scleractinian corals. Biochem J (1997) vol. 322 ( Pt 1) pp. 213-21

Hollibaugh. The Biological Degradation of Arginine and Glutamic Acid in Seawater in Relation to the Growth of Phytoplankton. Marine Biology (1976)

Iturriaga and Zsolnay. Transformation of some dissolved organic compounds by a natural heterotrophic population. Mar Biol (1981)

Jin and Qian. Amino acid exposure modulates the bioactivity of biofilms for larval settlement of Hydroides elegans by altering bacterial community components. Mar Ecol Prog Ser (2005)

Jin and Qian. Amino acid exposure modulates the bioactivity of biofilms for larval settlement of Hydroides elegans by altering bacterial community components. Marine Ecology Progress Series (2005)

Lehman and Porter. Chemical Activation Of Feeding In The Caribbean Reef-Building Coral Montastrea Cavernosa. The Biological Bulletin (1973)

Lewin and Hellebust. Utilization of Glutamate and Glucose for Heterotrophic Growth by the Marine Pennate Diatom Nitzschia laevis. Mar Biol (1978)

Mayer et al. Bioavailable Amino Acids in Sediments: A Biomimetic, Kinetics-Based Approach. Limnol. Oceanogr. (1995)

McAuley and Cook. Effects of host feeding and dissolved ammonium on cell division and nitrogen status of zooxanthellae in the hydroid Myrionema amboinense. Mar Biol (1994)

Roberts et al. Primary site and initial products of ammonium assimilation in the symbiotic sea anemone Anemonia viridis. Mar Biol (1999)

Smith and Dall. Metabolism of proline by the tiger prawn Penaeus esculentus. Mar Biol (1991)

Stanley and Brown. Inorganic Nitrogen Metabolism in Marine Bacteria: The Intracellular Free Amino Acid Pools of a Marine Pseudomonad. Marine Biology (1976)

Streamer et al. Photosynthetic carbon dioxide fixation in zooxanthellae. Mar Biol (1993)

Swanson and Hoeegh-Guldberg. Amino acid synthesis in the symbiotic sea anemone Aiptasia pulchella. Mar Biol (1998)

Teugels et al. Kleptoplasts mediate nitrogen acquisition in the sea slug Elysia viridis. Aquat Biol (2008) vol. 4 (1) pp. 15-21

Williams et al. Amino acid uptake and respiration by marine heterotrophs. Marine Biology (1976)

Related posts:

1. Amino acids and reef aquarium: Aspartic acid
2. Amino acids and reef aquarium: Alanine
3. Amino acids and reef aquarium: Arginine

Unfortunately it seems that the Reef Actif is really no match for my heavy invertebrate feeding: today I measured some pretty amazing levels of both phosphate and nitrate: 0.2 ppm PO4 and 25 ppm NO3! I have never in the last 12 years measured anything even close to this high nutrient concentrations in spite of a few really awful catastrophes I have had over the years. Typically, both nitrate and phosphate are undetectable by the best test kits available and I won’t accept anything else.

It s possible that I could get better results by just increasing the Reef Actif dosage but that would be too costly. Besides, with nutrient concentrations this high, I must deal with the crisis as fast and as effectively as I can. Based on my previous experiences, nothing beats organic carbon dosing in achieving this goal.

So, I’ve restarted my Vodka + sugar dosing with 10 ml/day dose (6 x ~1.7 ml using dosing pump). I expect nutrient levels to start to drop in a week and will report how it goes. I will continue to add Reef Actif in modest amounts to see if I can observe other positive effects other aquarists have reported but obviously I will not rely on it to take care of inorganic nutrients in the future.

[Update]

I hate when people are too fast to make negative comments without researching the issue first

Turns out that Tropic Marin Reef Actif is far from expensive if compared to almost any other additive you can buy for your reef aquarium. Here are some calculations I made:

Costs for Tropic Marin Reef Actif, dosage 1-3 spoons/500 litres per week, 500 ml container, 50 € (all prices in €)

Related posts:

1. Tank update, July 2009
2. Tank update, June 2009 (Updated)
3. NP-Biopellets, the story so far