How measure PH?

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Originally Posted by Brent F

I'm not looking at controlling PH. I'm trying to determine which product to use to raise alkalinity. Some, such as baking soda, lower PH while many comercial products raise it. I was trying to determine whether a product that raised PH or lowered it would be beter to use.

Holmes-Farley did an excellent article on the affects that alkalinity supplements have on pH. This should answer your question.

Here's the article:
http://www.advancedaquarist.com/issues/may2002/chem.htm