Raising and lowering DWC ph levels?

i was wondering if its ok to use aquarium ph up and ph down?
if so how much should i use for just over 30 litres?
i need to know my ph is at about 6.0 - 6.1
my clones need to get in my brand spankin tub

any ph up or down will work. I have used both and see no difference. And to determine how much you need just try a little bit. wait 5 min then record your ph. If you need more add a little more. When you get desired ph, know how much you used and you will have a basic idea on what you need every time.

sweet thanks man