guys, in aquaponic system where health is important they use only KOH and CaOH
sodium ho sucks(builds up in ur system), they put it in our tap water to lower the ph(alla softener) bull shit
KOH and CaOH, don't take my words 100% as i haven't tried any of these, but i've read a lot on aquaponic systems and i've been working on one for some time now, KOH and CaOH isn't just a ph adjuster in aq. system, it is also a nutrient supplement(K and Ca) for growing plants with fruits(tomatoe etc.)
the point is to not add shit that plants/animals don't need in such dosages...if added too much it can show as a bad taste or burned plants etc.
ph should be maintained by you, not by ph up or down
using RO water helps you to keep the pH down, adding phosphor or pottasium ions brings the pH up again....then you can compensate with adding tap water that holds more +ions if you ph goes down or RO water if your ph goes up too much
ph up or down is needed when u fuck up the feeding/watering schedule
basicaly, read bio-tokes water chemistry or and kind off chemistry book involving ion balance in water suspensions.
hope i gave some info here, else sorry for babbling