Ammonia high in 2 year old tank!

[petertc]

Hi, I've had a 38 gallon tank for 2 years and haven't had anything like this happen. The other morning, I looked at the test results (API) and the ammonia was way high. nothing like this ever happened, so I did a 15% water change, and then another maybe half an hour later. The ammonia fell, and it was fine for a day or two. Then, it skyrocketed with no warning and killed most of the cories. Did another water change and am stumped. Can anyone shed any light on this, and if so, some advice?

Info: 38 gallon rectangular tank, two filters, (15 gal. and 30 Gal. rated) air stone, weekly water changes, 19 fish total befor the cories died: Pleco, catfish (name unknown), 2 clown loaches, 3 green barbs, 5 swordtails (babies), 7 cories (1 inch). I feed them every other morning. All fish have survived 2 Ich "waves".

 

[OrangeCones]

Did you have a power outage?

Is the heater working correctly?

Both of those can kill off your biofilter rather quickly.

 

[MissFishy]

I would check and make sure all fish and plants are accounted for, a hidden rotting fish or plant can raise the ammonia levels quickly. Also, have you just done a large tank cleaning or changed out the filter pads? When you do your water changes are you treating the water from the tap before adding it to your tank or just dumping the water conditioner in the tank afterwards? Have you tested your tap water for ammonia?

 

[petertc]

its me again

the heater is working fine, I treat the water beforehand, and the water tested ammonia free.

 

[MissFishy]

Hmm, that is a mystery. The ammonia has to be coming from somewhere though, be on the lookout for a source. (this usually turns out that something like a mound of uneaten food or a dead fish is rotting in an ornament or the corner somewhere).

 

[Matt Nace]

What do you treat the water with?

What kind of filters are they(brand)?
Also, you did not answer some questions they asked you above such as have you changed the filter media/floss out or cleaned it?

 

[bmoraski]

when i have to change my carbon filter ( when its falling apart lol )
i keep a close eye (testing next few days) because ive had problems with ammonia spikes.
ive read some people keep 2 pads at all times in there filter so when they have to change one they dont have any problems.

 

[petertc]

okay, I use novaqua to treat the water and I changed the filter pads in the second filter last weekend, but the problem started on tuesday. There were no dead fish or stuff like that when I vacuumed last weekend and still no bodies for some reason. I think they might have been eaten, but i only noticed them missing the day after noticing the problem.

 

[petertc]

although they may be wedged inside an ornament. something to check today. thanks

 

[bmoraski]

keep us posted

 

[Matt Nace]

There may be a chance that when you changed the filter pads, you lost some bacteria which could explain why the ammonia could build up. This also can happen if you dont have enough biological filtration for the fish load.

Are they Whisper filters on that tank?