The most concentrated ph down available is shockingly by Advanced Nutrients, their ph down is the most concentrated....in fact you will need to dilute it before use unless your dealing with really large tanks like 200 gallons and larger.......
Most get a quart bottle of it, then use a separate quart bottle to dilute it down for use...do not get this shit on your skin or anything else as it will burn your skin and also ruin anything it comes in contact with......think battery acid....and treat it just like you would concentrated battery acid......dangerous stuff at this level of concentration for sure and precautions are needed like gloves and proper ventilation......
AN ph down is about twice maybe even three or four times as strong as Technaflora...
Common sense always wins out doesn't it?nitric is used to make explosives, sure you want your name on a list?
whats the pH of your 0.6 ec source water?
if you're in north america, grainger industrial supply has what you want.
you do realize that HNO3 is going to raise your N.
i'd be more concerned about that in flower than the P in H3PO4.