How Freshwater Deep Sand Beds Work

[DeeDeeK]

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[thrak76]

Good information! My sand beds aren't quite as deep, but i'm thinking of finding some blackworms to add to them. Seems to be, at least, an interesting experiment to try. I'd say my sand is at minimum 2 inches deep, with some areas towards the back at around 3 inches. Deep enough, you think?

 

[jackiomy]

How many blackworms should you have to start out with? Could I do this in my 55g?

 

[DeeDeeK]

My last post before this one, with the video and no text, is an accidental post. Whoops!.

The following is a video showing my tank and a few of its fishes. It is really just meant to show the quality of the haziness in the water. It looks much much worse than it really is in stills so I made a quickie little video. Ok, so I got a little distracted by the fishes. Note the pond-like stillness.

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In order to achieve decent oxygenation, I use a weak filter and place the floor of the outlet spout almost on level with the surface-tension of the tank water so a maximum of turbulence and disruption of the surface-tension takes place, allowing the water to absorb as much gas as possible. The intake is down near the bottom of the tank, so the circulation is tank-wide even though it's pretty slow. I've dropped quick cure in the top of the filter in order to watch its circulation and it does pretty well reach the whole tank fairly quickly.

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Back to the haziness and dead shrimp!!!!!!!!!
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Yeah, I found one more dead shrimp around noon. Three down out of eight, but I must qualify this all by saying I only got them a day before the disruption of the substrate so they might just be casualties of the shock of capture, bagging, and introduction to a new environment. There were tons of babies, too, but I bet they're all eaten up by now. If they are alive, they're probably hanging out in the old biomedia worm sanctuaries on the bottom. Baby shrimps really seem to like those old noodles.

I am feeling pretty sure that by disrupting so much of the substrate at once I must've released ammonia produced by aerobic decay of the roots I unearthed. I say it was aerobic decay because the sand was it's usual off-white color around the roots, which were decayed. The sand in anaerobic pockets turns from very slightly greyish to black depending on how little oxygen and how much organic matter there is in it.

My belief is that this ammonia was being metabolized by nitrifying bacteria between where it was generated (rotting roots which were at a minimum about an half an inch deep, down to probably two inches or so) and the surface. Since there was no increase in nitrite, I think the nitrifying bacteria were definitely eliminating the ammonia and the nitrite quickly before it could emerge from the substrate; there was no accumulated nitrite to show a "backlog" in the nitrifying region.

Another theory is that the ammonia was the result of the sort of denitrifiers which produce ammonia as an and product rather than N20 and N2. This is done in anaerobic layers. Perhaps the sand was slightly anaerobic - the roots were black after all. Or perhaps the anaerobic layer was deeper down and the ammonia had diffused upwards and accumulated in a transitional region where it wasn't truly anaerobic but there wasn't enough oxygen for nitrification to happen, between the bottom layers and the top where nitrification was neutralizing ammonia prior to its escaping into the aquarium water. That way the inbetween sand could have acted as a reservoir without having to be grey and anaerobic.

What the haze could be, I can't tell. Bacteria released into the water? Bacteria multiplying rapidly to metabolize organic compounds released from the sand into the water?

I wish I had a microscope, an oxygen probe (to measure oxygen at different levels of the sand), a spectrometer to analyze what chemicals are present in various samples, and a real scientist to assist me. At least the microscope, the oxygen probe, and maybe some sort of field guide to fresh water microbes and protozoans, microfungi, and algaes.

The measurements for the water quality are: NH4 0, NO2 0, N03 (non-zero but seems well below 5ppm)-all because I got scared and added Amquel Plus yesterday when I found the dead shrimp, PH 6.4. I've been sniffing for H2S since I uprooted the decaying root systems and haven't smelled it. The water does and has always smelled like really mild garden soil.

The ph is steady because I use a combo of Seachem Neutral Regulator plus Discus Buffer. They are phosphate based buffers which precipitate out all the calcium, magnesium, and other metals. I add Seachem Equilibrium, which uses CaSO4 and MgSO4 to raise GH without affecting KH and also has FeSO4, MnSO4, and KSO4, in order to restore the water to about 5 or 6dH. Algae doesn't cause any trouble, I think because the plants outcompete it for other essentials. I've kept the ph set low like it is because I've been concerned about ammonia because I'm on an experimental path with this aquarium and I want to protect the critters from it. For those not in the know, the lower the ph, the lower the amount of ammonia and the more ammonium, which is not toxic, or at least not very toxic, to fish and inverts.

You'd think with all the sulfates, Equilibrium might be a nice source for sulfate reducing bacteria to produce H2S with?

In my future tank, I will start with the Seachem ph buffers and hardness restorer but once I'm convinced the water chemistry is stable re. ammonia and nitrites/nitrates, I'm going to stop adding them and try letting the ph swing the way Walstad style tanks do.

Ok, so tomorrow morning I will measure for NH3/NH4, NO2, and NO3. I'm trying to find an H2S test kit for the aquarium (or any affordable H2S test kit for water). When I can afford it, I'd like to get an O2 and a CO2 test kit. I think a iron test and a phosphate test kit might be good, too. It would be good to know more of what's going on in the water with all this experimenting.

 

[DeeDeeK]

How many blackworms should you have to start out with? Could I do this in my 55g?

In my little tank, I put about as many worms as I could scoop out of a bucket at once with a plastic fork. So for a 55g I'd guess four to six fork-scoops. I know, real scientific. Every couple of months I reseed the tank with about half the maximum that I can get on a fork.

To distribute them, I put them in a large large cup of water, and used a turkey baster to swirl them around and then sucked up a squirt at a time and squirted them to different parts of the tank I wanted to be sure they reached, like inside clusters of vegetation between the stalks and stems and the two piles of old spent biomedia noodles where the worms can hide better from my kulhi loaches (who are like ferocious wolves to the blackworm!). I also tried to get them evenly distributed in all other areas of the tank.

They'll live not just in sand but gravel too, if you don't vacuum it too thoroughly, and almost surely they'd thrive like mad in a Walstad tank.

Good information! My sand beds aren't quite as deep, but i'm thinking of finding some blackworms to add to them. Seems to be, at least, an interesting experiment to try. I'd say my sand is at minimum 2 inches deep, with some areas towards the back at around 3 inches. Deep enough, you think?

My guess is that if your sand is close to 2.5" deep on average, it should work fine. When I first set up Justin's style DSB in a small tank, it didn't cycle for months. It turned out to be just shy of 2" deep and Justin told me add more sand. So I added until it was from about 2.5 to just shy of 3" deep and it cycled in three weeks. Go figure. It's just one anecdote but Justin told me it really should be three inches.

My current tank is really closer to 2.5" than 3" deep in sand on average probably.

 

[mel_20_20]

:worthy: I am grasshopper.... may I come learn at your knee.... O great wise one.

 

[DeeDeeK]

Update: No more deaths! The haze is still coming and going, which seems really weird, but it's mostly going. The NH3/NH4 is 0, NO2 is apparently non-zero but it's below the API test kit's lowest measurement, NO3 is below 5ppm but non-zero. The ph is 6.4, thanks to the Neutral Balance and Discus Buffer.

There are two surving super-red cherry shrimp and three tiger shrimp, from an original population of four of each. The shrimp are crawling around and foraging like healthy shrimp should do (I forgot to mention before that the shrimp had stopped foraging much and were swimming around a lot). I've counted the fish, species by species, and found none missing, found no other dead critters, and there seems to be a bunch more planaria hanging out in plain view than I've noticed before. No signs of plants melting or otherwise suffering.

It seems like the tank is having a micro-cycle. I'm pretty sure the worst is over. Actually losing less than 50% of shrimp from the shop I got 'em from upon introduction to my tank could just as easily be from the shock of transport and adjusting to a new environment as it could be from a tiny ammonia spike in ph 6.4 water. It's a bit much, but not really so strange.

I'll post my next water test results and anything interesting (in my eyes) that comes up.

 

[DeeDeeK]

Good water quality. Yup. Apparently things are clearing up. The haze is improved, still there, but much much thinner; a definite haze rather than cloudiness. The NH3/NH4 is 0, NO2 is 0, and NO3 is maybe up to 5ppm but seems marginal - it's definitely non-zero though.

Despite this, one more super-red cherry shrimp died. I looked at it one hour and thought maybe it wasn't doing so well, wasn't grazing. Next hour, I looked and so I had some more fertilizer and one less shrimp. The one remaining red shrimp seems happy enough and the three tiger shrimp seem downright vigorous. 50% fatalities so far. I wish I had more test kits covering more chemicals. Especially I'd like to find an H2S test kit for home aquariums.

If anyone knows of an H2S test kit for home aquariums, please chime in!

My new theory about the shrimp deaths is this: I've got no good theory! Could be the shock of introduction to the tank and the fact that the LFS which the super-cherry reds come from doesn't quarantine real well. Could be unknown, unmeasured toxins like H2S. Could be ammonia. Could be I pushed my stocking level past the limit of the sand bed's biofiltering capacity (I'm probably triple the strict 1"/gallon rule and then there's the worms, snails, shrimps, and planaria). Could be space aliens! The unearthed rotten roots do seem to correlate with the problems but thats all they do. Correlation is not good evidence of a causal connection. There could have been a blue moon when the roots came up, too, but that wouldn't prove anything either. It just seems like the roots would have something to do with it. No measurements show anything scientifically. I don't even really know where the ammonia came from!

I've documented the problems with haze, shrimp deaths, ammonia, and unearthed roots in order to be honest with all readers, so it's understood that while I'm very sure about a lot of things to do with my particular FWDSB, it's still an experiment to some extent. I've begun a notebook journal of the aquarium in order to make the experiment more formal.

The following is not so much about how FWDSBs work but about how things like FWDSBs are developed and what things hinder discovery and development within the hobby. It is a rant.

One issue I have with our hobby is the plethora of anecdotes and opinions about things, which often generalize the specific: sand beds are dangerous because they'll bubble hydrogen sulfide into the water and it'll kill your fish in a minute is one example - in reality SOME kinds of sand beds can SOMETIMES develop pockets of H2S and apparently, there's been a few incidents where when a bubble of it escaped something poisoned the water and killed all the fish quickly, though there isn't proof it was H2S just the correlation of the bubble with the deaths.

I read these anecdotes and opinions all the time online and hear them in the LFSs in the city and they often contradict one another or even contradict known facts. We discourage ourselves from exploring many options with things like the inches of fish per gallon debate and the sand beds are all dangerous rumor. Sure, plenty of people want a standard gravel bed tank with colorful gravel, plastic plants or a few decorative live ones, absolutely zero algae and your basic petshop fish and there's nothing wrong with that and nothing wrong with the water changes, root tabs, vacuuming, and powerful filtering which go along with them if you don't mind them since they're needed for that sort of tank. Neither is there anything wrong with ADA style "nature" tanks or those european planted tanks with all their CO2, nor is their a problem with "El Naturale" tanks. What it wrong is the misinformation and disinformation we all spread to one another which keep hobbyists from understanding the real principles which underlie how the different styles of aquaria work. Those same principles are what underlie the FWDSB I propose. Those same principles can be applied creatively to develop other variants of aquariums. Sort of like basic ingredients in a kitchen being used to create a number of different recipes.

Thing is, we don't parlay in terms of the underlying principles of aquaria. As Walstad points out, each aquarium is a little semi-independent ecosystem. The principles have to do with biology and chemistry and physics, which can seem a little challenging, but what the heck, so are the principles underlying organic farming, which doesn't require an engineering degree to succeed at. So, one can stick with established styles and techniques of aquaria keeping and not have to worry about having a comprehensive understanding of bacterial ecology, plant nutrition, soluble gases, etc. as long as one sticks with authoritative sources for guidance and instructions like Tom Barr or Diana Walstad or Takashi Amano. Or one can forge ahead, building on the knowledge and experience that precedes, and do so successfully if the knowledge base being built on is sound and one is careful to try to understand what they learn - for example I study Walstad's "Ecology of the Planted Aquarium," read Tom Barr online, and a few other sources on saltwater DSBs and live rock biofilters and have a basic understanding of biology from college and high school biology classes and I asked Justin at Ocean Aquarium how to do one of his style FWDSBs, then put what it all together and learned more by experimenting, measuring and paying close attention to what was happening (should've been taking notes, though) and now I [believe I] have a fairly complete understanding of how my sorta FWDSB works and sure knowledge on how to duplicate what I've already got. Or one can fumble along without deep understanding, being guided by anecdotes, apocrypha, rumors, and uninformed misinterpretations of scientific knowledge all from well meaning people who feel reasonably sure of the soundness of their advice.

That last route, with the anecdotes, etc., just restricts potential for creativity at best, and at worst leads to disasters. Since it's popular to be cautious and conservative, most of that advice is just restrictive, like the inches per gallon rule or the notion one's filter ought to circulate 10x the capacity of the tank per hour or that deep sand beds cannot work with freshwater. It bothers me immensely to see this sort of stereotyped advice, "popular wisdom." It also bothers me to read the debates such as the one on what is a better guideline or system for stocking a tank. They are full of arguments based not on facts or even good theories necessarily. Just check out all the discussion of stocking - is it about oxygen supply and CO2? How does oxygen best get absorbed into the tank and what about CO2 levels and how to manage them if necessary? Or is it about bioload? Or is it about being humane to fish and what are their healthy behavioral needs anyhow? How do we know what the oxygen requirments or bioload of a fish is? Length? Volume? Mass? Activity Level? How is it known that corys are only happy in groups of six or more? (I have three happy seeming cordydoras harbrosas, by the way, who hang out together and forage and have nice vivid markings and are active - so who's to tell me they're not happy?) or that blue rams definitively need a 20 gallon tank minimum? And does the behavioral approach to stocking a tank take into account its decor, planting, tank format (cube, tall rectangle, column, rectangle, globe, etc.)?

In discussing my FWDSB I'm sure I'm a violator according to my own rant, above. However, I try to discuss the "ingredients" to my "recipe" so it amounts to "this sort of FWDSB works in such and such a way and does such and such things" rather than lay down a law like "DSBs work in freshwater." For example, my tank has worked well with miniscule power filtration, like 25gph for a 9 gal tank, and no vacuuming but I'd never say you should follow that as a rule - what if you were setting up a gravel bed, non-planted tank? No, I can't tell you general, hard and fast rules based on my experience. I CAN tell you the principles underlying the functioning of my aquarium with it's FWDSB and I can tell you how to SPECIFICALLY set up a FWDSB of your own which will work and because I understand the underlying principles, I give you some good advice on what to do if you want a FWDSB like mine except you don't want worms. I don't have to rigidly insist on worms. It can be done differently and the result will work a little differently, possibly have a somewhat lesser biofiltering capacity for example, but it can be done.

It would be unfair of me to give general advice on not vacuuming and weak filtration to people not using an aquarium technique which that works with. Just the same as it is not fair of people to push the sort of general advice we find on FW sandbeds, heavy filtration, fertilizers, stocking levels, etc., when it really only applies to specific cases or is based on principles which the advisor may be quite unfamiliar with.

Thank you for indulging my rant. As a liberated sorta girl who looks up to Diana Walstad for her creative, inventive, and independent thinking in the hobby, I just had to put my two cents in on the sloppy thinking/communicating in case it resonated with anyone out there reading who might then decide they'd like to discover this hobby for themselves, free of restrictive dogma and superstition.

Coming up soon: A step-by-step description of how to set up a FWDSB, with a list of the specific plants as well as the critters I've already said I use. This all minus the dopey experiments like burying gouramis. I'll list and briefly discuss the chemicals I add to the water, like Excel for BBA once in a blue moon and Seachem Neutral Regulator, Discus Buffer, and Equilibrium. Though I don't believe they're needed, I do use them and they do work.

 

[DeeDeeK]

Mini update: I forgot I'd used Life Bearer medication against some protozoal gunk on my ottos. Didn't put carbon in filter or do a water change at all. Then a few days later I added shrimp! Life Bearer is an organophosphate, very similar to common bug spray and to nerve gas. Kills arthropods good. Use too much and it'll kill your snails, planaria, and possibly worms. Even fish if you use too too much, I understand. I learned this the hard way, twice now. I really need to keep track better of medication usage! I killed all my mts and planaria once from using too much and now my shrimp from not clearing it from the water. Fortunately no fish fatalities.

Yeah, the remaining 2 shrimp are twitching and not foraging. Had two fatalities this morning.

ammonia 0, NO2 0, NO3 5, ph 6.4, all non-arthropod critters seem happy and healthy.

 

[jm1212]

i would be more comfortable with it if you did more water changes, but its an interesting write-up.