Why is my ph is usually very high, I mean off the chart on the bottle (I use the strips). I did a 20% w/c on Feb 7th and have added 6 of those ph tablets (not all at once) to finally get it down to between 7.0 and 8.0. How do I get it lowered without using those tablets. I can't afford to buy the tablets like that every week. Also, should I be doing weekly w/c's or is once a month enough. Right now my Nitrates are kinda high so I will be doing w/c another one this weekend.