high P.H

Question
We have a 55 gal tank which was set up on the 18/12/06 containing 6 male guppies and 3 small suckers. The PH settles at around 8.2, is this too high. We have a silver sand substrate with live plants and lava rock, we do a 25% water change every 5-7 days but the PH will drop down to about 8 and then rise back up within a few days. We have tried a 15% water change every day and got the PH down to 7.6 which is the same as our tap water but this will rise back up as soon as we stop doing them daily. The ammonia and nitrite levels are at 0 and the nitrate stays around 5. What could be causing the high PH and is there any way to lower it without using chemicals and get it to stay stable. Thanks.

Answer
Hi Martin,
That is a little high.  I don't see how the substrate could be causing the problem or the lava rock.  Do you have any other rocks or shells in your tank? Certain rocks and shells can raise the ph.  Be sure to vacuum your  substrate each time you do a water change just in case it could be dirty and causing some of the problem.  I really don't like to use any chemicals to lower ph and never have.  I have only used driftwood and that usually lowers it.  It will discolor your water for quite awhile and you will have to use carbon in your filter to help remove some of the color in your water.  Make sure your driftwood is safe for your aquarium if you are collecting it yourself and not purchasing it from an aquarium supply store. It will sometimes float for quite a while.You can weight it down with rock or glue it with aquarium safe glue to a piece of safe rock .  You can buy wood that is already attached to a piece of slate and that will help it to sink. Try the wood for a while and see if it helps at all.
Another alternative is totally changing your fish to a type of fish  that do really well in a higher ph. I don't know if you would want to consider that but sometimes that is the best choice.
I hope the driftwood helps with the ph. It really should.
Hope this helps!
Karen