Ph extremly high in fry tank????

[KingVinnie]

10 gl tank with 40 platty fry.

pH is through the roof 8.8
Main tank is 150gl. water is exchaged every couple days from the 10gl to the 150 to keep the fry water clean. Main tanks water is fine. After the exchange the water of course is the same in the fry tank as  in the main tank. After a few hours I test the fry tank and the pH is off the scale.

The only thing that is in the fry tank is:
Sponge filter
Small rio pump (used to excange water)
Thats it, no gravel,plants, ect.

To see my setup goto:
http://www.kingvinnie.dynip.com/aquaria/mytanks/index.htm
Lossing fry daily

Thanks

--------------
- KV
www.kingvinnie.com

 

[dattack]

What's the makeup water pH?
Tank water pH?
Fry tank pH? 8.8

A couple of guesses.  Your main tank contains some kind of chemical/acid that helps in lowering the pH and keeps it constant within that range.  Although driftwood can do this, I see you don't have any driftwood in the main tank.  Once that water is tranferred to the fry tank, the pH rises to 8.8 because your water has a high KH (hardness).

Other reason is that there is something in your fry tank or a chemical you might have added to the fry tank that acts as a buffer.  Maybe some limestone/crush coral/pH buffer is absorbed by the sponge filter in the past?

Another reason is that the test kit is wrong.