Please Help-pH in rockwool too low

[RedEye69]

Growing in 6" rockwool, 6 weeks into flower in flood and drain. Every day I check pH in rockwool and it is around 5 (pH pen broke, so using drops). I up rez to about 6.5-7 to try and raise pH in rockwool each day. After flood rez is 6 and rockwool is 5.5-6, but the next day it's low in the rockwool again. Any ideas?
TIA,
RedEye

[hows.your.roof]

i would try skipping a flood cycle and flood with phed water ,maybe twice . just a idea

[Chabnoc]

You are not using reverse Osmosis water, are you?

[RedEye69]

You are not using reverse Osmosis water, are you?

Yea, been using it since the begining. And yes, I use Cal-Mag+ as well.
Here's pics of the white widow, which looks the worst.
I tried flushing them a couple of weeks ago, because I thought there might be salts built up in the rockwool, but it didn't seem to help. This is weird, the pH usually goes up.

[attachment=o138295] [attachment=o138296] [attachment=o138297]

[hows.your.roof]

any bugs

[hows.your.roof]

nutrient strength

[RedEye69]

No bugs, been looking real good for them under leaves. PPM= 980

[hows.your.roof]

my ladies are 11 days in flower at 650 ppm. no signs of def. ph 6.1 may be a little high but they seem to like it

[RedEye69]

i would try skipping a flood cycle and flood with phed water ,maybe twice . just a idea
Thanks, this seemed to help. I gave them plain H2O at 6.5 for 2 days and they have ben back on reg. floods and pH is about 6 in rockwool now. All trichs are cloudy now with a couple amber, so I think I'll be starting to flush within the week. WOOHOO, my first hydro grow and my first with anything but bagseed!!! I cut a couple of lower buds last night and smoked them today and WOW. Gonna be some stoney weed in a week. The next cycle I will be more conservative with the nutes.Got a bunch of clones veggin' and ready to go in the bud room. :jointsmile:

[RedEye69]

When do you switch to bloom nutes, when you go to 12/12 or a week or so later when they start showing.

[hows.your.roof]

mine were hand fed till they showed sex then transplanted. switched to bloom nutes, 3rd day of 12/12