My fish tanks' pH level is really high?

Stop using chemicals. It is much healthier for fish to adjust to a high ph than to try and change the ph. If it is really an issue, you need to look at what is causing it. What kind of rock? Why do you have pink gravel? (not related to ph just why...? haha). If you want to lower it, the best way is natural. Driftwood and peat moss are both known to lower the ph.