pH Problems during early flowering

[Dalek]

I'm currently on my 3rd indoor grow. I'm having the same problem as I did on all 3. First 6 weeks, they look great, then leaves begin to yellow. I recognized signs of low pH and began watering and feeding with pH 7.0, the runoff was 6.3. I spend a lot of time measuring pH but after seeing pictures, Sirius told me after seeing pictures that it's definitely pH and even though my runoff measures within the 6.0 to 7.0 range, the pH around the roots is probably 5.3.

I took the Master Class, and went through it several times and I didn't see anything that would prepare me for this. So, today I'm going to increase the water to 7.5 and see if this raises the pH at the roots. I'm using Happy Frog soil, and General Hydro Trio. I've been following Nebulas watering and feeding guides. I'm not sure what to do.

Help! (Please!)

Dale

[golfnrl]

Hello Dalek welcome aboard! PH problems are frustrating for sure. When you water and check the runoff PH do you check each pot, or just the one in question? How are you measuring the PH? Is your equipment calibrated? Can you put up some pics please? As a Master Class grad myself I do not want to or mean to insult you with basic questions...

[Dalek]

Hello,

Thank you for responding! This is my 3rd indoor grow in a 5 X 5 tent, HLG750R, AC Infinity controller.I use an Apera tester and calibrate it monthly. I,m using Happy Frog Soil and Gen Hydro Trio.

I began each grow with the plants looking beautiful up until about week 6.Then they begin to fade in color, and just look sick. . I've been discussing this problem with Sirius by him explaining the difference between runoff measurements and the actual pH at the root zone. This morning I fed with pH 7.4, runoff 6.0 so I have a way to go. My next watering will be 7.8. I think I'm on the right track?

Dale

[bboyfromwayback]

I used to get a lot of fade around week 6 as well. My plants didn’t look sick, the leaves just lost their color. Feeding nitrogen a little longer and upping the cal-mag should help. I also like to let the ph rise the longer into flower they go.

[Smallgrow]

Two point to contribute athough a different medium

I’m in living/super soil and switched to using a ph soil meter (BlueLabs) it’s not cheap but it gets to the root of the problem

I also had a similar problem on repeated grows in early flower and I resolved it by watering more. Overwatering is a problem of course, but under watering can lead to all kinds of deficiencies symptoms showing up cause the plant isn’t getting enough water for adequate nute uptake, more so in soil. For me these deficiencies were all chased with more nutes but that didn’t fix it, running wetter seems to have resolved it

[Dalek]

Sirius just sent me the following: "
"I thought I said that I'm pouring in pH 7.0. My runoff is 6.3-6.5" This is exactly the problem. Your runoff pH should be about the same pH as the water you put in. Your runoff being 6.3-6.5 would be perfect if you were pouring in water at 6.3-6.5.




If you pour in at 7 and the runoff is anything below 7, take the difference between the two and subtract that number from the runoff pH. The remaining number is roughly your rootzone pH. The picture below shows what I'm talking about.








To be absolutely clear, your runoff is not the same as your rootzone pH, which is what we're trying to fix. You measure your runoff pH to help figure out your rootzone pH (the pH at your roots).




Rootzone pH = Runoff pH - (Pour In pH - Runoff pH)



So, in your case (let's got with 6.3 runoff)




Rootzone pH = 6.3 - (7 - 6.3)

simplify
Rootzone pH = 6.3 - (0.7)

simplify

Rootzone pH = 5.6 <-This is the problem. Your pH isn't 6.3, that's the runoff that you use to figure out your rootzone ph. Your rootzone pH is roughly 5.6 and that's what's causing the issues.




Since your water comes in around 7.7, water your plants without lowering the pH next time and that should get you on the right track.




Sirius