What is the best ph

my nutes say to set your ph to 5.6 but is this what is best using hydro.???

in veg i set it to 5.6 but im now in flower and would like to know what my ph shud be.. i dont wana ruin what im growing so any hints n tips will be gratfully appreciated..

thanx in advance to all that help.

Any problems so far in flower? If not I say leave it where it is.

hi m8 , no probz yet lol.. the only thing i cud say is that everyday i need to re-set my ph coz within 12-24hrs it rises to about 6.1-6.3

i dont mind re-settin it but just wish it would stabalize.
sumtimes after a few days the ph falls to about 4.3 so does this mean this is when i have to change the water in the nft tanks.???

ive read sumwhere that when the ph falls like that it time to change the tanks... (is this true.?)

check out my journal,,,(white widow and bigbud afghani hydro grow) ive just started it so its not as good as others ive seen...
im taking cuttings tomorrow so will have more pics to add.

thanx m8..