Ammonia up - pH down - out of control and dead fish

[badwater]

New aquarium - 20 gal. Started w/ 2 Platys, 6 Zebra Danios, 1 Cory catfish. 1 week later has an out break of mouth fungus among the Danios (should have fertilized the garden with them all) Used antibiotics - the water change after a week and eventually lost 5 Danios. Finally all under control and have 3 sets of plants. After another week water ok added 2 Otocinclus and 1 smaller platty. After 3 days the first Oto died. After 1 week the second started acting strange sticking up by the water line on the side and the next day died, too (after the pair laid eggs - obviously unfertilized - they didn't do anything). Water temp 78-80. Now the Ammonia is above 5 and the pH below 5 and no matter how many water changes and Amquel can't get it to correct. HELP!
The filter is a penguin 125 and there is a large airstone as well. There are 2 rocks in there - one of those multi color (sanstone or limestone that you buy at the aquarium store and 1 dark with white striations - don't know what also bought at the aquarium store) Any body have any ideas?

This topic has been moved to it's current forum.

[reefrunner69]

Well, first...Amquel will give a false positive for ammonia unless you are using a salycilate test kit for testing. Second, if the ph is truely 5, you don't have any ammonia in the tank, you have ammonium, which is not toxic to fish.

What is the ph of the source water? Have you double checked the ph kit?? If your tank is cycling, you can expect some drop in ph, but to go to 5, you would already have to be starting low. My first instict is not to trust the ph kit.

[badwater]

thanks.- the source water (tap) is good here ph7.5 with the same test kit
the kit is a Tetratest Laborett

We had 5.0 mg/l Ammonia brought down to .25 w/Amquel and a 50% water change
Now pH is 5
and Nitrite is .3 mg/l

any more ideas?

[fishfreek]

You need to increase the oxygen level in the tank. This should help rase teh PH.

The oxygen level in the water has a direct corolation with the PH level and the lower the o2 level in the tank the lower the PH will be.

Do the fish appear to be gasping? Are they toward the top of the tank?

[loganj]

I would not have started with that many fish in a 20. IMO, three danios would have been plenty to get the cycle done. Danios, platys, and corys are fine though...all pretty hardy fish. Not so for the otos. They die fairly easily and do not tolerate poor water conditions such as ammonia or pH fluctuations. Give it some time and your water should stabilize. I think I'd take a water sample to the LFS and get it checked there to verify your test results.
Logan J

[CRaZeeeBiTcHisH]

what are you feeding the otos?