is PH strain specific?

Hey, i have grown before and this is my first time doing a hydro grow, i read up ALOT on it before i started. i have been keeping my ph at about 5.7 and i have 5 plants that are blueberry strain and 3 that are big bud strain. within - the last week, the ph has been drifting up and seems to slow down when it gets around 6 - 6.2 and i left it that high for a day just to see what happens, and it the ppms in my nut. sol. went down alot faster, does that mean that this strain likes a higher ph and absorbs the nuts. better leaving it a little higher?