question on ph

heres my problem I have my plants in 5 gal buckets with plenty of bubbles,my plants are in there 6th week of flower and the past few days my ph has been way low,Im useing GH micro and bloom 1 part micro 2 parts bloom I have to add ph up every day now for 3 days I also use h2o2 in my add back water,my roots look ok,I dont know if this is normal or not this is my first indoor hydro grow thanks in advance for any help

...how are you measure'n your pH?
...are you measure'n your ec also?
1 part micro, 2 parts bloom....sounds like the Lucas formula I currently use, I donot have to adjust my pH at all as long as my ec is around 1800 (tds 1300 ppm @ .7 conversion)

I have a digistick ppm meter and for ph I am useing the old drops in a vial cuz my calibration solution isnt here yet,my ppm is 1400 and ph starts aroung low 6.0 or a tad lower the next day im down to like a 5.0? dont know why this is happening it was stable through the whole grow till now thats whats alarming to me something has to be going on and I have to catch it fast im in the 6th week of flower and dont need problems now

....is your tds meter @ .5 or .7 conversion? , sounds like your solution is pretty strong, imo.
...here's a link to the Lucas formula I posted awhile back. >>> https://www.rollitup.org/hydroponics-aeroponics/338720-lucas-formula.html#post4267692

Im useing .7 conversion,and discoverd I read my notes wronge and was due to change out my nutes,as far as running a bit high on ppm your right got a slight nute burn on the leaf tips but not bad,its almost time to start cutting back on the nutes anyway they look to be 2 or 3 weeks away from harvest thanks for the advice peace and grow on