Sudden ammonia spike in established tank?

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DaveB

Fire Eel
MFK Member
Feb 22, 2008
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I noticed that my big fish were breathing hard this morning so I did a 50% water change (with deep gravel cleaning) and added some aeration - I figured it might just have been an issue with the filters having reduced in flow a bit and affecting the surface agitation. I checked the nitrates anyway and they were 10 before the change, so I just assumed it was that. More air = problem solved.

Except I just went back there and they're still gasping. I've never seen a datnoid gasping before. Puzzled, I dug out the ammonia test kit. Oddly, it's sporting a .50 ammonia level even after today's water change. This is higher than I'd expect even if I had a large fish die overnight (none did).

This is a 2 year established tank with no history of anything at all. It's a 125 running two FX5s. This should be overkill. There haven't been any power outages, and the flow is slightly reduced and I guess the FX5s are due for some maintenance, but it hasn't been that long.

How the heck did I suddenly get a ton of ammonia?

There are three things I can think of:

1) I added three 12" black Aros to the tank (not their permanent home, obviously... a 415 is). But that was 3 weeks ago and they haven't had big appetites. This started this morning.
2) perhaps there was something wrong with the market shrimp I fed them last night and they had upset stomachs and there was a sudden onslaught of poop. Or maybe it was OK but I fed too much (possible. I'm not usually a big powerfeeder but I got a bit carried away last night. It all got eaten though.)
3) My remark just yesterday about not having lost a fish in this tank in nearly a year jinxed me despite knocking on wood, and the entire tank is doomed.


Still... it's not like I dumped an entire bag of food in or anything. They got maybe double their usual portion, tops. How on earth could that have caused an ammonia spike from nothing to .50 even after a 50% WC on a tank with 2 FX5s? This is nuts.

Assuming the BB didn't mysteriously die (no idea how that'd happen), shouldn't 2 FX5s worth of bio media be able to handle this?

I'm kind of worried, because it'll be a few hours til I can do another water change. I've never seen ammonia this high in an established tank before, not even when I thought I killed some bacteria in my overcrowded planted tank.
 
did you use any kind of meds??

meds kilss BB
 
The other day I added a half dose of Melafix to treat some bala shark wounds... I've used that stuff at repeated full doses before without any issue though.
 
Just a thought...did you lose power overnight? If so, and the filters were off for an extended period, won't the BB start to die off? and when power is back on, bad water gets dumped into the tank?

/shrug
 
Start countin your fish. Maybe you lost another. Happened to my daughters tank. My 6 year old comes uo to me saying she cant see the fish. I take a look, sure as sh|t theres a dead molly stuck to the back of the intake. Get rid of it, do a 50% w/c. Next day, same sh|t. I start counting the fish... woops, I'm 1 short. I start flippin rocks and find a baby clown loach. Take em out, w/c again. Tank is crystal clear.
 
If I lost power I think I would've had a flashing alarm clock so I don't know about that. And I counted all the fish and none were gone. I'll check again when I get home tonight.

I didn't feed them last night and a few hours ago they all seemed fine. I'll need to check ammonia levels again.

I have a hunch that maybe the catfish that ate two entire pieces of large shrimp may have puked one of them up or something, and that combined with the large volume of poop after the bigger feeding may have just spiked it up. Hopefully just temporarily. I guess I'll see when I test the levels. In theory after the 2nd 50% WC it should be down to .25 since the reading was .50. Here's hoping it's 0 again.
 
When you do your WC do you add any type of live bactiera such as Stability, Cycle or Super Bac.
Also when you service one of your Fluval Filters do rinse your ceramics and sponges in tap water Rinse them in a bucket of your Aquarium water
 
When I thought I killed the BB in another tank of mine it was because I got some tap water in the bottom of the sink mixed up with the media. But these two FX5s have not been rinsed with anything but tap water and haven't been touched in 2 months or so. One is due, since the flow is reduced, but that can wait.

On other filters I do rinse the sponges in tap, but not the biomedia, even though I'm mostly convinced that there's no chlorine in Chicago tap anyway (I kept a carnival goldfish for over 2 years in untreated tap water).

As for additives, I just use whatever API's highly concentrated 1ml/10gal product is that I got at the petco around the corner. No bacteria additives. I've never needed anything like that before.
 
I have a feeling that the ammonia spike and the gasping symptoms may not necessarily be related, as I have seen first hand with my own fish in the past begin to gasp quite heavily immediately after the addtion of melafix to treat a wound. back when I worked at the LFS, I had a few customers say the same thing, so I stopped recommending it..for a while though, I was on the bandwagaon :)

in fact, if I am not mistaken it used to say right on the bottle to increase aeration -not sure if it still does.

apparently, the melaleucea extract can 'consume' oxygen in the water coloumn (ie reacts with the dissolved O2)

the thing is, that obviously .5 ammonia is not good, but usually the level has to be higher than that with most fish to have them all up at the top gasping..somewhere more like 4-5 mg/L rather than 0.5..
 
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