I'm a sucker and dropped 30 dollars on a gallon of the lower, but I'm not a fan of ordering anything on the internet (except for seeds of course, and even then its with a money order). This works great on my tap water (pH of 8.5). I also got a quart of the raise for the times that I use a really strong dose of fertilizer (last month of flowering), or for that random time that I've lowered the pH too much.

The GH raise and lower work out great for me. I use them in soil at the moment, but I also plan to keep using them for my next growing endevour, DWC hydro. Anyways, I recommend them.