Help!

Put in some prime. Also before doing another water change test your tap water, could be that it has alot of chlorine that is messing with your fish and may have killed you bio filtration or it could have nitrates in it. Either way put in some prime, should help neutralize your nitrates.

I just did a 30% and added prime, have 2 casualties =( I quarantined the others in another tank for now... I always add prime, I pour it into the stream of water from the hose when I am refilling the tank... Good thing I have the day off, I would have came home to a dead tank. I tested the tap, other than my water being a little soft, which I have some GH booster I use, perameters are great. My test strips don't show any chlorine or nitrates. The tank water has high nitates of 40 low PH of about 6, and .2 ammonia. I don't know what happened?

Tap water is as follows: alkalinity 80ppm PH 6.8 nitrate 0 nitrite 0 GH 25ppm

Hrmmm. Not sure, I had a similar situation earlier this year and it turned out that the water company was cleaning their lines and added a bunch of extra free chlorine. But that should show up on your chlorine tests. Sorry for your loss!

is that ur ammo lvls after the wc? if so u probably had high lvls that caused your problems

Yes that was after the water change... I should have tested it first, I used my 6 in one strips immediately, and my ammonia strips are separate. Lets assume that was the case, what would have caused an ammonia spike in my tank? The tank has been cycled and running for about a year now, always using same routine... EI method 50% WC every sunday.. My drop checker was showing a higher than normal dose of co2 if that would effect anything.

quote from http://www.bioconlabs.com/nitribactfacts.html

Nitrobacter will grow more slowly at the high pH levels typical of marine aquaria and preferred by African Rift Lake Cichlids. Initial high nitrite concentrations may exist. At pH levels below 7.0, Nitrosomonas will grow more slowly and increases in ammonia may become evident. Nitrosomonas growth is inhibited at a pH of 6.5. All nitrification is inhibited if the pH drops to 6.0 or less. Care must be taken to monitor ammonia if the pH begins to drop close to 6.5. At this pH almost all of the ammonia present in the water will be in the mildly toxic, ionized NH3+ state