You need to go and get a ph tester and abide by the rules for proper growth, I disagree with the other two post a PH tester can be found at your local plant shop or swimming pool shop. The other two post did give you some methods that you can use to adjust up or down, but you do need to test for proper PH and that not down by adding nukes!!!!!!! That just cause other problems, a TDS meter will tell you about the Parts Per Million of Total Disolved Solid that what you use for adding Nukes. Bizzy