WILL BREAKING DOWN TANK AND CLEANING GRAVEL CAUSE AN AMMONIA BURST?

[BettaShelly]

I have a 20 long tank that's been set up for about 5 or 6 years with no problems until recently. I have a hang-on-back filter, plus a sponge filter and plants. I just have gravel substrate with no under gravel filtration. I am wondering if you don't have to break down and clean this type of gravel every 5 years or so because I have started to register ammonia and have never had ammonia register. I also have nitrates showing up on test strip. Both values are within the safety zone, but I just had a Glowlight Tetra and A Corycat die. I know Corys are incredibly sensitive to Ph and Ammonia. If I break down and clean gravel will this cause a ammonia bloom that will kill the fish or is the sponge filter an adequate storage of beneficial bacteria?

Anyone with lots of experience that can help me? I appreciate any knowledge on this type of setup. Thanks.

 

[Byron]

There are some issues to be concerned about, beyond ammonia itself. On the substrate issue, the risk in disturbing it is any pockets of anaerobic bacteria. Disturbing these could cause real problems including death of the fish.

Gravel is not a suitable substrate for cories primarily because of the bacteria issue that gravel encourages. Sand does not do this, plus the fact that cories do need sand to filter feed naturally.

Ammonia should never be sen in planted tanks as the plants grab it rapidly, so that could signal something. Nitrates are detrimental to fish, there is no "safe" level regardless of what ill-informed individuals may suggest, so keeping nitrate as low as possible consistently is the goal.

I'm being very general here, it would help us (other members may have more detail) if you could post numbers for ammonia, nitrite, nitrate, pH, and GH.

 

[Alice B]

I'd move the sponge filter and the fish to a bucket or another tank before cleaning that one up. Then maybe thin sand. I'm not an advocate of thick, having watched anaerobic pockets form in my sand bottom reef in 2002

 

[BettaShelly]

There are some issues to be concerned about, beyond ammonia itself. On the substrate issue, the risk in disturbing it is any pockets of anaerobic bacteria. Disturbing these could cause real problems including death of the fish.

Gravel is not a suitable substrate for cories primarily because of the bacteria issue that gravel encourages. Sand does not do this, plus the fact that cories do need sand to filter feed naturally.

Ammonia should never be sen in planted tanks as the plants grab it rapidly, so that could signal something. Nitrates are detrimental to fish, there is no "safe" level regardless of what ill-informed individuals may suggest, so keeping nitrate as low as possible consistently is the goal.

I'm being very general here, it would help us (other members may have more detail) if you could post numbers for ammonia, nitrite, nitrate, pH, and GH.

OK, here goes: Nitrates= 20-40 ppm -

There are some issues to be concerned about, beyond ammonia itself. On the substrate issue, the risk in disturbing it is any pockets of anaerobic bacteria. Disturbing these could cause real problems including death of the fish.

Gravel is not a suitable substrate for cories primarily because of the bacteria issue that gravel encourages. Sand does not do this, plus the fact that cories do need sand to filter feed naturally.

Ammonia should never be sen in planted tanks as the plants grab it rapidly, so that could signal something. Nitrates are detrimental to fish, there is no "safe" level regardless of what ill-informed individuals may suggest, so keeping nitrate as low as possible consistently is the goal.

I'm being very general here, it would help us (other members may have more detail) if you could post numbers for ammonia, nitrite, nitrate, pH, and GH.

OK, Nitrate 20-40 ppm Nitrite=0 pH=6.8 No Ammonia

I do have one of my small betta tanks with sand and do like it. Is it so dense that does not allow ammonia pockets? I gently vaccum any food off top.

I have kept fish on and off since 1996 and never had a water quality problem. Maybe I am over feeding. With Corys, Glowlight Tetras and a betta everyone needs different foods and may together just too much

Still wondering if I change substrate to sand and only have sponge filter for bacteria, when I put all fish back in will it overload and cause ammonia?

 

[Byron]

Nitrates at or over 20 ppm is too high, this will over time weaken the fish leading to other issues. Have you tested the tap water for nitrate, and if so, hat is the number? This will determine if it is in the source water (wholly or partly)which is one issue, or if nitrates are occurring within the tank which is another issue (and more easily handled). Nitrates should be kept as low as possible.

Sand is no more of a problem than gravel when it comes to anaerobic areas. But sand is healthier for cories and similar substrate fish from a bacterial perspective. You don't need a deep sand substrate, my sand tanks had about 1.5 inches when spread evenly. My 5-foot 115g had 4 inches, but that was a large tank with huge sword plants that needed the depth for their root systems. But it never gave trouble, and in fact I never touched it at water changes, the cories did the housekeeping very well! Anaerobic patches under rock or wood are normal and part of a healthy substrate.

Your best bet against any amonia are fast growing plants, and here substantial floating plants (Water Sprite, Water Lettuce, Frogbit, some stem plants left floating) are ideal.

 

[BettaShelly]

Nitrates at or over 20 ppm is too high, this will over time weaken the fish leading to other issues. Have you tested the tap water for nitrate, and if so, hat is the number? This will determine if it is in the source water (wholly or partly)which is one issue, or if nitrates are occurring within the tank which is another issue (and more easily handled). Nitrates should be kept as low as possible.

Sand is no more of a problem than gravel when it comes to anaerobic areas. But sand is healthier for cories and similar substrate fish from a bacterial perspective. You don't need a deep sand substrate, my sand tanks had about 1.5 inches when spread evenly. My 5-foot 115g had 4 inches, but that was a large tank with huge sword plants that needed the depth for their root systems. But it never gave trouble, and in fact I never touched it at water changes, the cories did the housekeeping very well! Anaerobic patches under rock or wood are normal and part of a healthy substrate.

Your best bet against any amonia are fast growing plants, and here substantial floating plants (Water Sprite, Water Lettuce, Frogbit, some stem plants left floating) are ideal.

Being an animal lover and a long time fishkeeper I am not like that. I want all my fishies to be happy and healthy. I have had Corys since my first aquarium and they lived a long time. I have read sand is betterk but didn't think it would be harmful to them to have gravel. My only concern about with sand is I have read it is harder for plants to grow in it because it is so compact. I have a large sword and several Java fern. The 20 gallon is pretty full and the fish love the plants. I don't know if I want to change to sand now, or give Corys away or have 1/3 sand for them and the rest gravel for plants. I'm gonna have to think what I need to do. The nitrates are definitely to high for Corys, but hate to part with them. Thank you for your advice. It has me started in the right direction. I'll do what I can to make sure Corys are happy and healthy

 

[Byron]

This hobby is full of misinformation and "old wives tales," sorry to say. Sand is without any question the premier substrate for all plants and fish, the only fish exceptions being some of the larger cichlids that do better with gravel. I changed all my tanks to sand about 9 years ago, and wished I had done it sooner.

There are more than 300 described and pending-description species of Corydoras in South America, and all live over a substrate that is sand (the vast majority), or mulm/mud, or a combination. There is not one species that occurs over any form of gravel, though there are a couple species that have a mix of sand and gravel. Observations have proven that the fish remain over the sand, so that tells us something (or should!). The fish have an inherent expectation of taking up a mouthful of the substrate, filtering out food, and expelling the substrate out the gills. They cannot do this with gravel.

Another issue is bacterial. Gravel grains are large enough that food can get down and the cories cannot filter feed, so the food causes bacterial issues. Barbel erosion is often blamed on the roughness of the gravel, which is certainly true if it is rough (sand too if rough) but it is the bacterial issue more often the cause. To see cories upending themselves in sand, a third of their length, is one of the joys of keeping these fish.