I personally use the gerneral hydroponics PH up and down, yes. As needed.

When I only had tap water, my PH was very high, so I had to use ph down. Now that I have a water filter, my PH usually goes a little too low for hydro after I add nutrients and supplements. So I generally need no more than 2 drops or so of ph up to get my PH to 5.8 where I keep it. They're very poweful! A few drops is all you need, so quart bottles will last forever.