I recently constructed a DIY slate background for my 125 gallon African Cichlid tank. In order to insert the background, I had to move some of the sand (big mistake, I know). After a few of my fish died from the toxins released from the sand, I removed the rest of my fish to prevent them from dying. What I need to know is what to do from here. Should I let the tank re-cycle? Should I empty the entire tank and start over with new sand? What steps should I take to get my tank back to a suitable condition for my fish?
Deep Sand Bed Problems
- Thread starter Breanne
- Start date
First off sorry for the loss of your fish... when you have sand as a substrate you need to regularly vacuum it when doing water changes (every 2 weeks or so) this keeps it from going anaerobic and causing what happened in your tank. This will also keep your tank cleaner and more stable as you will be removing waste and left over food that gets in there. At this point I would vacuum it to clean it and let the tank cycle through. Good luck
I would guess you need to let the BB take care of that for you. Toxins from sand? Not sand guy. Just keep having bouts with sickness and am a huge fan of Stress Coat and Methylene Blue.
When disturbing substrate there are a couple of things that can happen. One is indeed toxins like hydrogen sulphide being released at once. When into the water column, it pretty much evaporates/ makes a reaction and is neutralized but on it's way out of the water it may affect fish if you released too much at once and fish were in the way. However, it's more harmful when bottom feeders dig into the substrate rather than anything else.
The other issue is an ammonia spike which normally follows when one disturbs the substrate way too much. In both cases when you do that, you need to follow with a large water change or two. Then it should be pretty much safe for the fish. This is more likely the reason your fish died? Have you measured the ammonia/nitrites?
And why having a deep sand bed?
Siphoning a deep sand bed will not prevent either of these issues happening in the future. Sand compacts back within minutes. When the substrate is deep, it doesn't get enough oxygen into the bottom layers and anaerobic decomposition occurs. Anaerobic decomposition causes the production of harmful gasses such as hydrogen sulphide and others. It stays in there if you don't touch it, but once you disturb it, all this can go out at once.
If you have a thin layer of substrate, then because it gets oxygen, aerobic decomposition occurs instead, which produces CO2 instead and not hydrogen sulphide or at least not in high amounts. The CO2 as you know pretty much goes straight out via the surface agitation and doesn't harm the fish.
Both processes also produce ammonia. Disturb any substrate, it goes out into the water column. Siphoning can reduce the amount of organics those bacteria use to produce ammonia and gasses but to be honest it's impossible not to have organics in the substrate. Siphoning only helps to keep the substrate aerobic to an extent as it doesn't get clogged to the point of oxygen not reaching there.
And this sort of setup where one has "oxygenated" substrate is healthier for at least bottom feeders as it also doesn't promote harmful bacteria that may directly affect fish.
Best way to get nitrates out of the water is water changes and not a deep sand bed in which what happens one can't control.
The other issue is an ammonia spike which normally follows when one disturbs the substrate way too much. In both cases when you do that, you need to follow with a large water change or two. Then it should be pretty much safe for the fish. This is more likely the reason your fish died? Have you measured the ammonia/nitrites?
And why having a deep sand bed?
Siphoning a deep sand bed will not prevent either of these issues happening in the future. Sand compacts back within minutes. When the substrate is deep, it doesn't get enough oxygen into the bottom layers and anaerobic decomposition occurs. Anaerobic decomposition causes the production of harmful gasses such as hydrogen sulphide and others. It stays in there if you don't touch it, but once you disturb it, all this can go out at once.
If you have a thin layer of substrate, then because it gets oxygen, aerobic decomposition occurs instead, which produces CO2 instead and not hydrogen sulphide or at least not in high amounts. The CO2 as you know pretty much goes straight out via the surface agitation and doesn't harm the fish.
Both processes also produce ammonia. Disturb any substrate, it goes out into the water column. Siphoning can reduce the amount of organics those bacteria use to produce ammonia and gasses but to be honest it's impossible not to have organics in the substrate. Siphoning only helps to keep the substrate aerobic to an extent as it doesn't get clogged to the point of oxygen not reaching there.
And this sort of setup where one has "oxygenated" substrate is healthier for at least bottom feeders as it also doesn't promote harmful bacteria that may directly affect fish.
Best way to get nitrates out of the water is water changes and not a deep sand bed in which what happens one can't control.
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^^^THIS^^^
I do love the look of a deep sand bed, but with that comes more maintenance.........having to constantly stir up the entire sand bed. Nowadays, I typically don't keep a sand bed any more than 3/4" deep. A lot of times there'll be areas with exposed glass bottom, due to the fish stirring things around, but it doesn't really bother me any more.
To the OP, the damage has already been done. If you haven't done so, do at least 50% daily w/c for the next few days, and you should be fine. No need to change out sand, but you may want to consider either going for a thinner layer or start a regular routine(2 X a week) of stirring up the entire bed to prevent this from occuring again in the future.
The risk i believe is a rapid acidification and drop in oxygen from disturbing anerobic pockets. Water changes to stabilize the ph and remove the increased organics would be a good idea. Check ammonia.
I use a small pump and a length of hose tied to a stick to stir sand in my 180. Takes less than a min and gets under decore. If you've stacked rocks be careful as they can settle quickly with the fluidised sand.
I use a small pump and a length of hose tied to a stick to stir sand in my 180. Takes less than a min and gets under decore. If you've stacked rocks be careful as they can settle quickly with the fluidised sand.
Thanks for all your replies. I will keep the deep sand bed as I have always had them with both fresh and saltwater aquariums and believe they are great for biological filtration. My ammonia/nitrates have always been in check with a deep sand bed....until it was disturbed. It is to my understanding that deep sand beds are very beneficial for the water quality in an aquarium unless they become stirred or mixed up some how. Anyway...I did a 40% water change after the first fish died...then did 20% water changes every other day after that. My ammonia and nitrates are still high though....should I keep up with the water changes or let it re-cycle?
unless you are using a UG system of some sort with a deep bed of sand or gravel your gravel bio filtration is minimal, you need to be relying on proper bio filtration for this, canisters, sumps and to some extent HoB,s, while agreed gravel.sand and all decore help some with bio filtration they are not to be relied on.
My 180 is bottom drilled, I run duel reverse gravel filtration with 9" sponges on the intake stand up pipes, gravel is about 4" deep, the water comes up through the gravel rather than being pulled into it. this helps in keeping my white gravel clean, but i do not rely on this to be a bio filter. I run other filters for that witch comes back to the point, if you think your gravel/sand is a major part of your bio filtration you are mistaken.
My 180 is bottom drilled, I run duel reverse gravel filtration with 9" sponges on the intake stand up pipes, gravel is about 4" deep, the water comes up through the gravel rather than being pulled into it. this helps in keeping my white gravel clean, but i do not rely on this to be a bio filter. I run other filters for that witch comes back to the point, if you think your gravel/sand is a major part of your bio filtration you are mistaken.
I have a canister filter. The deep sand bed is controversial in the aquarium hobby but in my experience, it works well for what I need it to do....but this is beside the point. I came here for advice on what to do to improve my water quality after making a mistake by disturbing my sand bed.