sick tank?

[thincat]

I don't understand your PH problem? what is it without the buffer added? With only a polyp you don't need any buffering. Do you have lots of coralline aglae growing?

[Kurt_Nelson]

The pH will not go down because of not adding buffer to the makeup water. The pH may go down for other reasons... but not because of the makeup water issue.

When you have a lot of biological activity in a tank... say... like algae growth, or cyanobacteria growth... pH will naturally go down. The more biological acticity, the more tendancy for pH to go down.

Buffer is to increase alkalinity anyway. It does provide a quick pH increase, but that's not it's purpose. Do you know what your alkalinity levels are?

Also... if you only have polyps (zoas, palythoas, etc), stop the phyto. They aren't utilizing it.

[special lighting]

its cause my ph from fresh water is about 6.5
no coraline thats the good one right?
no alkaline test at the moment

[thincat]

The water that evaporates from your tank is as pure as can be. You should be adding that same pure water back. All the minerals and compounds stay behind and if that's not diluted with pure water it's going to build up and become toxic.

[Kurt_Nelson]

Originally Posted by special lighting

its cause my ph from fresh water is about 6.5

It doesn't matter. No need to add buffer to freshwater top off for the reason thincat mentioned.

no coraline thats the good one right?
no alkaline test at the moment

Might want to get one. Y'know the old saying... if you don't test for it, don't add it.