funky pH problem
My pH is @ 8.0 in my tank, and I'm not sure why. Here's a description of my tank, maybe someone could help me figure out my problem?
I have a small 5.5 gallon freshwater tank on my desk at work.
I originally filled the tank with drinking water from my local food lion, afterwards I've been doing weekly 1 gallon water changes with my buddies RO/DI water. I also use the RO/DI water for top offs. I have 18 watts of power compact light on the tank for almost exactly 9 hours a day, turned on and off via a timer.
I have 5 lb.s of some plain river gravel that I got from my LFS that I heavily rinsed before putting in my tank, a rena cal basic 50w heater, and a sponge filter. The tank stays @ 78 F. The tank's been up about a month and a half.
The only mobile life in the tank is a few Triops that occasionally hatch from old eggs in the tank (but don't usually last long), some ramshorn snails, a mystery snail and a malasian (sp?) trumpet snail. Once a week or so I drop in half a baby carrot for the snails to eat, it usually takes them 4-5 days to eat it.
The only plant I have in my tank is a bunch of Anachris that is constantly shedding leaves, dieng off, and growing back. I don't usually get all the fallen leaves out of the tank when I do a water change.
My ammonia, nitrates, nitrites are at 0. Do you think the dead leaves could cause the PH of my water to rise to 8.0, where it's at right now? Or, do you think there is some other factor that's raising the pH?
I tried to give all the info I could about the tank, if you need any more I will gladly supply it.