excess of carbon dioxide from the lack of air.... perhaps there isn't enough surface agitation for good gas exchange.also what kind of buffer do you add?i think it has to do with the water movement.

Actually that's what it is. More oxygen means bigger and faster gas exchange ( specially at the surface) So yes, More watermovement creates more ohygen, creates higer ph. With low O2 levels and slow gas exchange oyur ph will stay low. You can buffer it up, but it won't solve oyur O2 problems. And yes, you have to lower your heater, because you are about to adding new powerheads into your tank.. In my opinion if you have a daytime 8.0-8.1 PH level it pretty good for a FO tank, even for a FOWLR.If the Ph won't drop below 7.8 ( at night)you are good to go. The main reason the Ph drops at night is the photosynthesis( sunlight, in this case your light system). I wouldn't say that Ph was the reason you fises died.

Have you noticed any appetite problems, any spots or fungus problems?

Otherwise I have know idea what a f**ks caused the death..:-)

i check that every day to see if they try to gasp for air at the top or pass through the bubble wall more than usual,..no signs of that...I did notice he was getting a little lazy thats all, but at feeding time they all darted to the food. So consensus is i need to put the VAerator back on the ph right? I was trying to avoid all the bubbles, but without the aerotor its just circulating the water for even distribution, i guess

timers are also important..do more water changes and add more oxegen.do a small waterchange every week. even if your test kit says other wise..imo

lol we kindof avoided the ? there...im leaving that one airstone in, but do you guys go wax on or wax off with the aerator feature on the power heads?