How Freshwater Deep Sand Beds Work

Dr. Awkward - that really makes me want to research tannins. What makes them so great for fish, I wonder? I'm sure there are all kinds of complex chemical interactions involved, it seems like everything is like that in aquariums, once you really investigate.

Kk5kb - I'll certainly be following your progress!
 
I know tannins can be beneficial to a tank because they chelate toxic metals. They also inhibit some bacteria, including cyanobacteria. Before I made the switch my male flag fish had been fighting off a small bacterial infection on his head. I had been treating with frequent water changes. It was starting to look a little better but it wouldn't go away completely and I was considering using antibiotics, which I really hate to do. The day after I added the soil all signs of the infection disappeared and I haven't seen it since. I think his newfound perkiness was a combo of his infection finally healing up + a change in the water chemistry that alerted his internal clock that it's time to breed.

This whole experience makes me want to try using black water extract as an antibacterial astringent the next time I have a fish come down with a bacteria infection.
 
Dr. Awkward said:
I know tannins can be beneficial to a tank because they chelate toxic metals. They also inhibit some bacteria, including cyanobacteria. Before I made the switch my male flag fish had been fighting off a small bacterial infection on his head. I had been treating with frequent water changes. It was starting to look a little better but it wouldn't go away completely and I was considering using antibiotics, which I really hate to do. The day after I added the soil all signs of the infection disappeared and I haven't seen it since. I think his newfound perkiness was a combo of his infection finally healing up + a change in the water chemistry that alerted his internal clock that it's time to breed.

This whole experience makes me want to try using black water extract as an antibacterial astringent the next time I have a fish come down with a bacteria infection.
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Hey, I had an experience with my ram recently where he had fin rot on his tail. I experimentally used a turkey baster to inject lots of this compost-based potting soil down into the sand and a bunch got loose and settled all over the tank. The water picked up a very faint tannin/humic substance coloration AND the tail rot seems to have gone away. I didn't put two and two together!

Flag fish are from Florida and thereabouts, I think. The soil and rocks in that region are fossilized coral limestone, the water is quite hard and alkaline, and there's lots of swampy marshiness, so it makes sense that the flagfish would love the whole soil and coral thing. You know, if I were a fish, I think that I would like it!
 
I just wanted to report that I have NO sulfur odor in my aquarium today! I thought maybe if I changed some of the water, I would be able to detect it while the water poured into the bucket, but even then there was no smell at all.

I also wanted to say that I may have done something dumb. I noticed all these kind of light colored leaves at the base of my sword plant, and I picked them all off, thinking they were old. I think I might have just picked off all of the new growth! I have a lot to learn about live plants, I guess, LOL.

Oh, and I added a little blue female betta, and a male and female pair of african dwarf frogs. I can hear the male frog singing his mating call to the female frog at night while I'm in bed, I love it.
 
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I forgot, I had intended to copy/paste this awesomeness I found on WetWebMedia:

"Greetings. The "gas in the substrate" problem is wildly exaggerated within the hobby. Here's the basics: Anaerobic decay can result in the accumulation of a gas called hydrogen sulphide (H2S). In theory, because this gas is toxic to fish, any bubbles of H2S can harm or kill your fish. However, in practise H2S oxidises very rapidly, and once it is in contact with oxygenated water the H2S gets converted to plain old sulphur (or as the Americans spell it, sulfur). This reaction is so fast that it is for all practical purposes instant, so small amounts of H2S will be rendered harmless long before the concentration in the water reaches dangerous levels. Marine aquarists have learned to embrace anaerobic decay, and routinely set up filters (e.g., deep sand beds and mounds of living rock) that perform anaerobic decay. I also have yet to see a pond that *didn't* have masses of anaerobic decay going on in the thick, gooey mud at the bottom of the pond. But for whatever reason, freshwater aquarists are still skeptical. So let's put things into perspective. Anaerobic (or at least dysaerobic) conditions are normal in muddy freshwater substrates, and most plants actually prefer them to the clean, oxygenated plain gravel substrates we usually give them. Under anaerobic conditions the mineral ions they want are "reduced" and more easily absorbed than they would in their "oxidized" states. Plant roots carry oxygen into the substrate via a tissue called aerenchyma, which you can think of as being a bit like a snorkel. Some of the oxygen carried down to the roots escapes and immediately around the roots the conditions are partially, but not completely, oxygenated (i.e., dysaerobic rather than anaerobic). So wherever plants are growing, the actual risk of dangerous levels of H2S developing becomes even smaller. Occasionally poking the substrate with a stick to stir things up a little won't do any harm, and I always add Malayan livebearing snails to planted tanks because they do this automatically, behaving rather like earthworms do on land. In my view, these snails are indispensable and as you probably know they never, ever harm plants."
 
I had to add an airstone today, the fish were at the surface "breathing" hard in the morning, and as soon as I started the bubbles, they relaxed into normal respiration.

I dislike the look and sound of a bubbler, so I will put it on a timer to only run at night, when the plants are creating CO2 instead of oxygen, and hopefully that will be sufficient.

I figured that once I had live plants they'd create more than enough oxygen for the fish, but I guess if you don't have any source of surface agitation (such as an HOB filter) you can still run out of O2 despite all the plants.

I should add that this could happen in any aquarium, it wasn't related to my deep sand bed.
 
Very interesting stuff going on here. I just wanted to pipe in with my experience. Last year I setup a 29G with play sand, and put more in than I planned. It ended up about 4" deep. The tank is densly planted with lowlight plants. It's stocked with white clouds, a couple bamboo shrimp, and a TON of snails. MTS, ramshorns and brigs. Over this last year or so that it's been setup, the more course grains have worked to the top, and the finer sediment has sunk to the bottom. So far, I'm yet to see a single black pocket. Maybe there are some in there somewhere, but they're not visible against the glass. No matter how long I go between water changes (sometimes a month or so) my water parameters are always spot on, with nitrate never going above 20, if that. When you consider there are hundreds maybe thousands of snails, including several brigs, I'd say it's a HEAVILY stocked tank. Still, it's by far one of the happiest, most self sufficient, thriving little ecosystem I've ever had. the plants seem to love the sand. I tried to uproot a willow hygro the other day, and finally jsut gave up LOL. I do have to admit though, whenever I do disturb the sand in any way, I follow it immediatly with a massive water change, just to be on the safe side! But the water has NEVER stunk.
 
Anoxia said:
I had to add an airstone today, the fish were at the surface "breathing" hard in the morning, and as soon as I started the bubbles, they relaxed into normal respiration.

I dislike the look and sound of a bubbler, so I will put it on a timer to only run at night, when the plants are creating CO2 instead of oxygen, and hopefully that will be sufficient.

I figured that once I had live plants they'd create more than enough oxygen for the fish, but I guess if you don't have any source of surface agitation (such as an HOB filter) you can still run out of O2 despite all the plants.

I should add that this could happen in any aquarium, it wasn't related to my deep sand bed.
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Directing the flow of a powerhead or filter so that it causes the surface to roil gently over a goodly area actually will induce enough gas exchange to keep tanks oxygenated even with ridiculous stocking levels, especially if water from near the bottom of the tank is being drawn up and sent towards the surface. Actually, any disruption of the surface tension will boost gas exchange considerably. Doing it gently for some reason doesn't blow off much CO2. Probably because the saturation level for CO2 in water is so much higher than dissolved CO2 in water's equilibrium level with the atmosphere and oxygen dissolves so readily in water though its saturation level is much lower than CO2. Why agitation drives the CO2 out I haven't researched yet.

angyles said:
Very interesting stuff going on here. I just wanted to pipe in with my experience. Last year I setup a 29G with play sand, and put more in than I planned. It ended up about 4" deep. The tank is densly planted with lowlight plants. It's stocked with white clouds, a couple bamboo shrimp, and a TON of snails. MTS, ramshorns and brigs. Over this last year or so that it's been setup, the more course grains have worked to the top, and the finer sediment has sunk to the bottom. So far, I'm yet to see a single black pocket. Maybe there are some in there somewhere, but they're not visible against the glass. No matter how long I go between water changes (sometimes a month or so) my water parameters are always spot on, with nitrate never going above 20, if that. When you consider there are hundreds maybe thousands of snails, including several brigs, I'd say it's a HEAVILY stocked tank. Still, it's by far one of the happiest, most self sufficient, thriving little ecosystem I've ever had. the plants seem to love the sand. I tried to uproot a willow hygro the other day, and finally jsut gave up LOL. I do have to admit though, whenever I do disturb the sand in any way, I follow it immediatly with a massive water change, just to be on the safe side! But the water has NEVER stunk.
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Your tank sounds cool and echos the results of every planted freshwater DSB I've encountered. The DSB provides an enormous biofilter! With 0.25 millimeter sand grains, it has 64000 grains for each cubic centimeter and at approximately 1.5 square mm per grain gives 96000 sq. mm surface area or approximately 1 sq. ft. (a sq. foot =92093.04 sq. mm). If your sand bed's aerobic layer is just one square foot 1 cm deep it's got 900 cubic cm, therefore somewhat over 900 square feet in surface area!!!!!!

The anaerobic layer contains many common denitrifying bacteria such as thiobacillus denitrificans, which reduce nitrate to oxidize hydrogen sulfide of all things! There goes your toxic gas and your nitrate!

You can actually order cultures of multiple aerobic and anaerobic denitrifying sulphur/sulfide/thiosulfate eating bacteria which also break down mulm quickly. They are sold as supplements to dump down your outhouse crapper in order to break down the solids and eliminate that awful odor, which is made of H2S and mercaptan chemicals (which are sulfur based) - and they often list specifically the species they contain and are safe for fish, people, plants, and inverts. You can get millions of times the quantity of bacteria in all those aquarium brand mulm eating additives which don't reveal what species they contain. here's one source http://www.alken-murray.com/EZ6pib.htm Here's one which doesn't list the species but it's sold by the pound - and they also sell more expensive pond and aquaculture bacterial additives http://www.usabioproducts.com/descsst.html There's more but they're a little hard google.

Dang! Lost track of time and gotta go!

My LFS uses weak HOB filters (like rated for 1/2 the tank size at most) and planted DSBs. He stocks them in numbers similar to those of shops with mungo large central canister systems with aeration. His livestock is excellent!
 
I went for a walk today by a creek, and I was delighted to find a shallow area where the mud was loaded with clams! I had never considered freshwater clams, but wouldn't they be ideal for slowly turning the deep sand bed? I almost scooped up a few for my aquarium, but then I figured it might be best to find out more about them first. Apparently if they are the wrong species, you run the risk of their offspring parisitizing your fish... I just don't know how to tell which species lives in this particular creek.

What little information I've found on them hasn't been favorable, people say the clams just burrow in and disappear, but all I want them to do is churn my substrate, I don't care about watching them frolic. I suppose by now my sand probably has enough of whatever clams eat to support a few of them, as long as they are the right kind. I guess I am still undecided.
 
Anoxia said:
people say the clams just burrow in and disappear, but all I want them to do is churn my substrate, I don't care about watching them frolic.
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Clams frolicking!!!!:rofl:
 
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