Thanks for the reply. My co2 goes off at night and the ph raises back to between 7 and 7.5 before coming back on. Filter is flowing well and I've added a 100 micron pad to the top to try and polish but that hasn't worked. Been about a week. The water isn't green at all as I've put some in a glass to compare several times. Just hazy white. Finally, I know I added fish too early, but the tank came with the guppies since I got it second hand for a steal. I had them in a tiny tank for a week and I couldn't hold off anymore 😕
A couple of thoughts:
- 3 weeks and still getting nitrite readings: probably not fully cycled. You may want to check that ammonia, as well. I'd be a little concerned for your fish. pH of 6.5 will slow any cycling that is trying to happen, but pulling back on CO2 might destabilize your plants and cause some algae problems. I'd risk that an let pH rise back into the mid 7's.
- Do a water change to drop the NO2 and perhaps NH3, which might become a problem as ph rises above 7 (fish concern again). I suspect that you rushed the fish introduction a little and now have to do a balancing act to get cycled while preserving your fish. Keep your eye on NO2 and total ammonia and be prepared to do water changes if they rise. Seachem Prime can also be a quick life saver, but use it only as an emergency. While it's safe, I'd rather avoid it because it can reduce oxygen, which your BB need.
- Check your filter to be sure it's flowing well. Sometimes the internals may not be in position just right and you may not get the full output.
- Are you positive that it isn't slightly green in nature?
- 50 micron filter pads (Coralife Pure-Flo ) will clear it temporarily, but doing it several times may be enough until it works itself through.
- Be sure your tank is clean. Detritus, such as from over-feeding, can form bacteria that will cloud the water.