hothew84;2278718; said:
well the tank is new im setting up for my jack dempsey's you may have seen the thread i put up about it and the first week of tank cycle the PH was about 7.2 now it has fallin to about 6.8 and i was told that a JD should have a PH anywhere from 7 to 8.4 and for the stocking ill be putting in 2 jacks and 1 large pleco and the PH of the tap water PH is about 7.2 and the tank has been up and running for about 1 week i think i setup the tank with water and gravel on the 28 of september and it is now october 5 2008 and i dont do any water changes but i do do topoffs and the ammonia has gone, now im getting high nitrite levels is this the info you where lookin for i hope it helps
Okay... I think I know what your issue is. Your tank is cycling and the pH is decreasing because of the nitrogen cycle. I could get into the whole reaction but basically as ammonia converts to nitrite, pH goes down.
When you cycle an aquarium, you initially get an ammonia spike (which you did). Eventually, bacteria flourish to convert ammonia to nitrite, so your ammonia goes down, and nitrite goes up (check). Eventually bacteria will convert that nitrite to nitrate. In the meantime, pH steadily decreases. This leads me to...
Two important points:
1. You need to do water changes, not just top-offs after evaporation. When water evaporates, what's left in your tank becomes more concentrated, so your pH goes down even further, and your nitrates accumulate. Routine water changes are a must. They keep your nitrates down, and also they keep your tank water's pH from dropping too far below the tap water's pH.
2. As said before, it's much more important to keep your pH consistent rather than aiming for a specific value. Your JDs will be just fine anywhere from a pH of 6 to 8, but if the pH changes quickly it can be harmful or even fatal to them. So just use your tap water with no chemicals (except a good dechlorinator of course), and do weekly water changes to keep everything routine.
Does that help?