After an ill-judged experiment with Tropic Marin BioActif (an experiment that left me with 25+ ppm NO3 and 1.0+ ppm PO4) I found an article (“Filter and suspension feeders” at coralscience.org) that mentioned a new form of filtration that made a lot of sense to me: a solid source of labile organic carbon that would release carbon only through enzymatic action of bacteria. This means two things: first of all, it makes overdosing pretty much impossible and secondly it avoids most of the problems that results from heavy use of DOC.

The old 2 liter setup. Pellets were quickly clogged with bacterial biomass.

I started out with only one liter of NP-reducing BioPellets (NPBs). Considering the “bioload” this was clearly too small amount for my tank but for once I wanted to be cautious. Seeing that nothing died and that the pellets were quickly colonized by bacteria (product was not available in stores at this time and there were no user reports) I added a second liter of NPBs. This was the recommended amount for the size of aquarium I have but considering my quite unorthodox feeding regime I didn’t stop the dissolved carbon dosing completely but cut it to half instead. With this combination of solid and dissolved organic carbon the nutrient levels stayed pretty much the same as they were with twice as high DOC dosing. So obviously the NBPs were working as advertised and I had reached my goal which was not to stop DOC dosing completely but to reduce it to more sensible level.

After a couple of months I still had some measurable nitrate (2.5 ppm) and phosphate (0.04 ppm) and I decided to really go “overboard” and ordered 3 more liters of NPBs. Since I didn’t have large enough “reactor” for this amount of NPBs I made a simple open top canister filter from an old 10 liter GAC container and a small 1000 l/h pump and placed the 5 liters of media in there. At the same time I stopped DOC dosing completely.

5 liters of NP-Biopellets in a 10 liter bucket. Using modest (1000 l/h) pump and large diameter container results in slow water velocity which seems to give best results in my case.

The results have been wonderful. It seems that the “critical mass” for my aquarium was around 5 liters of NPBs. The water stays crystal clear at all times and nitrates are finally dropping below 1 ppm. Using many commercial foods with excess phosphorous I still must use small amounts of GFO (before NPBs 2000 ml and now about 500 ml). I feed about 3-4 grams (dry weight) of pulverized invertebrate foods daily which is equal to about one 500 ml bottle of commercial liquid invertebrate food.

My NPBs used to get clogged pretty fast with thick bacterial growth but now, with twice as much surface area for them to colonize, the need to stir the media has diminished significantly. This might actually be a good indicator for sufficient amount of NPBs: if you find your media clogging very fast you might need more pellets to increase the usable surface area. Of course nitrate concentration is also a good indicator.

Comparison of costs of different filtration methods. Assuming 4 x 54W T5 lighting, 18 hrs/day. Bulb replacement every 9 months, 30% of NPBs yearly

I would recommend NPBs to all reef aquarists who are feeding their tank with invertebrate foods. Don’t be afraid to use more than recommended by the manufacturer. All tanks are different and manufacturers can only make general recommendations. Although the cost might seem high at first glance, NPBs are still a lot cheaper (and easier) than maintaining a large enough refugium to match the nutrient binding capacity of NPBs. Electricity and replacement bulbs aren’t cheap! There are also some competing products coming to market so I would expect the price to drop.

Related posts:

1. New ideas for reef aquarium filtration
2. Weapons of Nutrient Destruction: cone and pellets with sugar on top
3. Back to spirits (Updated)

I think one of the problems is the definition of the term “Ultra Low Nutrient System.” It seems to me that this description really has nothing to do with the amount of nutrients in the system. Reading some of the forums where the term ULNS is most often used it looks like people understand ULNS as a system that uses some form of DOC dosing and/or zeolites to aid in nutrient export. Obviously that tells us nothing about how much dissolved nutrients there really are in the water. Some “ULNS experts” even insist that you should always have some measurable phosphates and nitrates in a “ULNS” reef aquarium. Talk about contradiction in terms!

However, the question remains: why are corals so stressed in ULNS systems that they suffer from chronic partial bleaching (“pastel” colors) and very quickly develop tissue necrosis after small and for most systems benign change in water chemistry? People like me have been using DOC dosing for more than 10 years and never had the kind of problems ULN systems have. Large number of people (including me) have maintained healthy reef aquariums with constant “zero” nutrients and high alkalinity for several years. You don’t have to be a rocket scientist to figure out that the term “ULNS”must mean something else than low nutrients and DOC dosing with or without zeolites.

So why not just be upfront about it and say you are using ZEOvit? It is very confusing when people describe their system as an “Ultra-Low Nutrient System” when it clearly isn’t. It is even more confusing when people claim that it is the low nutrients that cause the many problems so common with ZEOvit system. It is almost 100% certain that aquarium corals will never suffer from “too low” inorganic nutrients. Nutrition is a completely different story. Together with intentional heavy metal poisoning the lack of proper food is certainly a good candidate for many problems…

Truly L NS

What I would consider to be a low nutrient reef aquarium would be one with similar levels of dissolved inorganic nutrients that are commonly found at costal reefs. The “Ultra-Low” would be reserved for tanks with even more nutrient poor water, something like remote oceanic reefs.

Below is a recent study on water quality on several costal coral reefs in Australia. These values are a result of large number of measurements from several sites and I think these could be used as a guide to LNS aquarium. Many reefs have order of magnitude lower inorganic nutrient levels but getting aquarium water so clean might prove to be an impossible dream.

Note that the values are in ug/l (1 ug/l = 0.001 mg/l or 0.001 ppm).

Taking the annual mean values, a good candidate for a LNS reef aquarium would have 0.003 ppm PO4, 0.003 ppm nitrate and 0.2 ppm silicate. For phosphate, that’s 1/10th of detection limit of best PO4 test kits and 1/100th for NO3. Note that silicates are often too low in a typical reef aquarium!

Related posts:

1. Guidelines for some parameters from Kleypas et al
2. Water au naturel
3. Back to spirits (Updated)

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

Many people will tell you that skimming “wet” (adjusting skimmer so that removes more water together with organics) will result in more net export compared to “dry” setting. This is mostly based on the theory that there is less draining back of dirty water.There are some important points that are ignored, however. First of all, the foam head that is formed inside the riser tube is not really an inactive component. The concentrated foam functions as an elevator that can collect much more bacteria and other particulate organic matter than a more dilute solution. Furthermore, no reasonably designed skimmer will discharge the concentrated surface water. Instead, typically the water exists the skimmer from the bottom. I do not see how any significant number of surface active molecules could travel through high number of air bubbles and less concentrated water to exit from the bottom. After all, skimmers really work because they don’t do that.

But that’s just a bunch of theoretical mumbo-jumbo. There is an easy way to tell if your skimmer works better in dry or wet setting. Tune your skimmer to wet and let it skim for two days. Take a picture and clean the cup. Next tune it to produce very dark skimmate and let it skim the same amount of time. Now bring the water level inside the collection cup to the same level as it was with the wet setting and take a picture. Compare the pictures.

All skimmers I have owned export more organics with dry setting – sometimes much more. Here’s an example how concentrated dry skimmate is:

Skimmate produced by a (broken) ATI Bubble Master in 24 hrs

Filled with tap water, typical wet setting

Of course the ultimate test is how healthy and clean your tank looks. For me, skimming dry has always produced better results.

Related posts:

1. New ideas for reef aquarium filtration
2. Weapons of Nutrient Destruction: cone and pellets with sugar on top
3. Let it foam: Selecting a skimmer

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