drastic ph fluctuation

im abotu 25 days into flower and my plants in rockwool are having ph problems, i water with ph 5.5 water with nutrients, and within a few hours the ph in the rockwool cubes is up around 7 again...... i dont know how to correct this or what to do!!! leaves are starting to turn yellow and im having all the problems associated with ph being off!

could it be because my nutrients is not strong enough and the plants are absorbing them so fasst that the p.h gets thrown off?

ph your nutrients.

huh? im not sure what that means ?!

i check the ph of the water after i add the nutrients, and before i water my plants

then i check the run off water, or water in the cube and within 1 hour its up around 7 again!

youre probably overnuting... i rarely use nutes on seedlings, and only like once every third watering if that. my ph stays around 7 for seedling growth. i think you should give them a good flush with a ph neutral water, and let them be for a few days. keep temp at 70-75-80 (75 preferred), and humidity 50-60%. you can get a thermo//hygrometer at walmart for like 8 bucks (digital too!). you can get a ph tester for about 20 bucks at a local gardening supply store. hope this helps

sorry, their not seedlings anymore, 25 days into flower! i have a ph tester and i water with ph 5.5 water, the problem is within a few hours the ph rises to 7 and over!!

the plants are barely drinking anymore, and growth is really slowing down !

oh sorry, didnt read first post fully.... i just saw rockwool, thought rockwool cubes (seeds//cuttings). well into flower, your ph should be about 5.8 for hydro systems. im assuming you are using hydro, since you are using rockwool... which i should mention is a bit of an odd growing method, but if it works for you.. more power, so to speak. anyhow, i would only nute every other watering. get some ph down, (about 8 bucks) and adjust when needed. also, are you using a digi ph reader? it might need calibration. you can use their calibrations fluids, or ph neutral water. however if it also reads ppm/ec/ you should use the calib fluid. but your plants shouldnt be dying or struggling at ph of 7, might need to add more nitrogen to the mix. however, during flowering the plants use the most of potassium than anything else. check your levels on both and get back with me.

also i should mention that higher alkalinity creates nutrient lockup. that could be a problem. if the nutes have locked, they are no longer chelated and unavailable to the plant. post some pics if at all possible and i can help you out a LOT more.

i dont have a ppm meter, so when i mix my nutrients solution in a resevoir, i adjust it to ph 5.5 after all the nutes have been added......... then i water my cubes.... the ph in the cubes is 5.5 after i water them, but a few hours later it goes up to 7 in the cubes............ and im getting allot of leaves turning yellow with brown spots...... which is a problem i had before and it was because the p.h was off.

i guess i will try a flush with ph 6 water, and see if that will stabilize the rockwool ?

if possible, transplant into soil. get a good potting mix, and add micorhizzae. chappys power organics from plantitearth.com will work well. i dont know if you're a first time grower, but soil is very forgiving and much easier to care for. i dont know how you are flowering in rockwool cubes....

sorry they are rockwool blocks, about 3x3x4 inches...... they are in a tray filled with hydroton......... it is my first time growing....... i also have 3 plants in earth, and they are doing well!

you suggest i put the whole block into earth? you think it will be able to make the change from its whole life in hydro to earth ?