Why don't you just buy the pH up (
potassium hydroxide)
http://www.basementlighting.com/Merc...age=1/PROD/PH3 or pH down(
phosphoric acid) http://www.basementlighting.com/Merchant2/merchant.mv?page=1/PROD/PH4 bottles and adjust until correct. Also cheap pH testing kits (last 1 or 2 grows)
http://www.basementlighting.com/Merc...age=1/PROD/PH7