Ammonia in already cycled tank

[steelo]

Hi everyone,


Last night I performed a 50% water change and a good gravel vacuuming after a fish died a few days ago. I think the dead fish was sitting in there for about a day before I noticed it. Well, I tested nitrites/nitrates/ammonia just to be sure that the levels are all still good. I was reading about 0.5ppm ammonia but no nitrites and about 10ppm nitrates. This is concerning because it seems like something is producing ammonia faster than the bacteria can absorb it. The tank is also stocked with a few live plants which I’ve been told should help absorb ammonia along with the bacteria. I also cleaned the filter media using the water I drained and it was absolutely filthy. I didn’t notice any uneaten food on the bottom and all fish are accounted for…My question is, what could be producing these levels of ammonia?


Here are the parameters:


45 gallon aquarium

Temperature – 75 degrees

Ammonia – 0.5ppm

Nitrites – 0ppm

Nitrates-around 10ppm

 

[Colin_T]

If a fish died and was left in a tank for a day, it would produce huge amounts of ammonia and cause the levels to go up rapidly. If it dies at night, the plants won't use any ammonia because they need light to do so.

Ammonia could also be coming from your water supply.

If the filter was really dirty, then cleaning it might have removed a large portion of the beneficial bacteria and they should recover in a day or so.

Reduce feeding for a couple of days and do a 75% water change and gravel clean the substrate every day until there is no more ammonia reading.

 

[steelo]

Thanks Colin, I figured the dead fish (I removed on Sunday) probably produced massive amounts of ammonia but hoped the bacteria would have absorbed it by now. I will continue to vacuum the gravel every day until the ammonia levels drop. I just checked my water supply and it reads 0 ppm ammonia

Thanks!