Help new growth turning yellow

[Smokeybear0815]

Hey guys my plants are in week 6 of veg about week 7 and have now developed yellowing on the new growth. Ive been attempting to treat with cal mag plus and it hasnt gotten better or worse. Any ideas?

[PRIMO]

Watchya growing in? Watch ya feeding em? What kinda lights ya got? Nice pics BTW.

[Rwise]

Whats the PH? What I see is a PH/root zone issue, need details of your grow. Or hit the link at the top of this page "Plant Problems" and look it up.

[Smokeybear0815]

I try to keep it at 6.5. I have 2 monitors and each one says different. One says its 5.4 the other says 6.8. In think my ph is low. Maybe and iron deficiency!?

[Smokeybear0815]

So I have one Ph monitor thats reading at like 5.4 and another one saying 6.8. Really thinking the ph may be low? I went out of town for a week left my uncle to take care and he let me with this. Growing in a green house blacked out cause started in winter and weather conditions, soil is fox farm ocean breeze, using house and garden products under 2 1700e gavita pros.

[Rwise]

Has your PH meters been calibrated? I calibrate mine regularly, even though I have not found it off more than 0.1. Is there another grower near by that you can gain a test from?
I have to agree I also think your PH is low, maybe not 5.4 low but.

[hairyman]

Some of the soil in some of the pots appears to have a green tinge which could mean algae and thus overwatering. Is that possible?

[homegrown]

Well, until you get your Ph meters straightened out its pretty difficult to determine what your problem might be. One reading 5.4 and the other at 6.8 isnt good at either end of the scale. I would get myself a Ph meter that has calibrating solutions and re-check your run-off.

[3Berries]

A good pH meter is essential as is maintaining it. They should be stored in a special solution when not in use I found out. You need some KCl 3M Electrode Filling Solution.

But I have been struggling with yellowing at the top for two years and have found the solution for me. My problem was NOT adding calcium, using rainwater.

But Calcium Chloride (CaCl2) applied in a strong solution directly to the soil at a 1/4 to 1 cup a day. I mix 1200-2000 ppm. The higher amount if the soil is staying too wet.

My needs are special because I have high CO2, around 2k-3k all the time in the winter.

This has cured the mythical LED bleaching. As with the CaCl2 treatment the LED issue becomes canoeing if they are too close.

The yellow tips are the key, if I don't do anything, or raise the light or reduce the nutes it only progresses to full leaf yellowing and die off. The leaf will not recover.