What causes PH drop?

LOL... I'm a fan of recycling. No need to use something new. Thanks I'll try to bolster the pH. My fish seem fine.

 

It's likely an oxygen issue, at those levels. I would get some airflow into your house from the outside. Possibly hook the skimmer inlet up to an airline run outside.

 

yeah I heard with the a/c on usually the ph drops, but once you have outdoor air venting your ph comes up????

 

Yes. What happens is that air inside the house gradually gains carbon dioxide and loses oxygen. It doesn't affect people because it's a small difference, but it will definitely hurt a tank over time.

Once you open the window for a few hours in the room with the tank, or run the skimmer line outside, you get air with a higher oxygen to CO[SUB]2[/SUB] ratio, and stop having those problems.