Rising ammonia

[Olga]

Hello! I have a 75-gal tank that has cycled by Thanksgiving. Soon after we bought 10 fish and waited 3 weeks. Everything looked good, so we bought 10 more fish about a week ago. Right now we have 19 fish (6 glow tetras, 4 molies, 3 guppies, 3 ghost catfish, and 3 catfish). I have a Penn Plax Cascade CCF3UL Canister Filter For Large Aquariums and Fish Tanks – Up To 100 Gallons. After I added my last fish, ammonia went up to 0.25 ppl. I thought it was OK until my guppies started to die. I vacuum gravel once a week and change about 25% of water at the same time. In the last week, I changed water 3 times to try to bring ammonia down, but it's still at 0.25. I keep on adding AmmoLock to protect my fish, but I can't do that for too long. I reduced feeding to once a day instead of twice and I give them as much as they can eat in 3-5 mins. What should I do? Keep on adding ammoLock until BB increases sufficiently or add something to the filter? How long do you think it'll take for the BB to grow? Thank you for advice.

 

[HopeGR]

How often are you feeding? I upgraded to a 20 from a ten gallon 2 months ago and I hardly get ammonia - and what raises it is food and fish waste. It is usually a problem with tanks 10 gallon and under, meaning small tanks. And ammolock doesn't rid it - it just tries to contain ammonia and not have it rise quickly. Weekly water cycles are fine, however, I believe I have read people with this problem should do a daily water change of 10 percent until it disappears.
And sadly, guppies are very sensitive fish that die quickly. I think it's the overbreeding that's the problem, though they do need stable water. I have given up on them.

Oh, I just read you feed them once a day now. If you maintain that then ammonia will definitely go down.

 

[Aiken Drum]

What are your other water parameters? pH, nitrite and nitrate?

While 0.25ppm ammonia is a sign your tank isnt fully cycled sufficient for your stocking, ammonia at that level shouldn't be harmful in the short to medium term unless you have a high pH. Perhaps there is something else going on causing your fish deaths, maybe your other water parameters can shed some light. Ammonia is a slow killer, perhaps the fish have historically been kept in higher ammonia prior to your current levels and the ill health and deaths is only now becoming apparent.

Also, compare the ammonia test from your tank to a test on some bottled water. The bottled water will be 0ppm. 0ppm can sometimes look like 0.25ppm.

Water changes will be more beneficial than any ammo lock. Up them to whatever you need to keep your ammonia + nitrite combined below 0.5ppm until your system can keep them at 0ppm on its own, rather than relying on chemicals which in reality might not be doing anything.

One thing i would say is you doubled the bioload in one go which is a bad idea. 30% increases in stocking is considered safer to not overload the system while it catches up. If you have 10 small fish then add 3 more small fish, not another 10.