New Growth Yellow & Slowed Growth - Need Diagnosis Help

Well I posted this over in the plant problems forum but with 120 views and no replies I thought I may have better luck over here with people using SubCool"s soil recipe. [HR][/HR]I need some help with diagnosis and solutions. This is my first grow in SubCool's supersoil recipe. The plants were doing great until a couple weeks ago when I started to notice the new growth taking on a lime green color. It starts at the base of the leave and works out to the tips which remain green the longest.[HR][/HR] I filled the pots 1/3 pure supersoil, next 1/3 mixed 50/50 with base soil, and top 1/3 base soil only. My temps run about 74-76 F. I do not think it is a deficiency but seems to be more of a lock out.[HR][/HR] I am only using water that I ph to 6.4-6.8. I do suspect my Milwaukee meter was out of calibration, and have since upgraded to a Blue Labs pen ph meter. I have a low cost 2 probe soil ph meter that shows the soil ph above 7.0. I had thought the dolomite lime added to the super soil would buffer the soil and keep it at 7.0 but think it has risen above for some reason.[HR][/HR] The main problem is the top leaves yellowing. The problem is getting worse, and growth has slowed significantly. I am also starting to see a few leaves on the bottom now yellowing. I am only about 1 week into flower so if I don't figure this out I think it will significantly impact this run.[HR][/HR] Here is what I tried so far. A couple days ago I gave a little compost tea. This may have made things worse as the ph of the tea was about 8.0. Today when the yellowing on top was worse, and I also noticed a few lower leaves looked like they had phosphorus deficiency from lock out I sprayed them with a foliar spray of Cal Mg. My guess is this is a Calcium lockout phosphorus lock out, or an Iron lock out due to high soil ph.[HR][/HR] I need help! What next, maybe a top dressing with some more lime? A top dressing with some more supersoil? Thank you for your help. [HR][/HR]View attachment 2678622

7.0 pH is not the perfect pH for cannabis plants. The soil needs to be somewhere between 5.6 and 6.2. You could be getting lockout because of that.

I humbly disagree, 5.6 is too low for soil. Soil ph should be 6.5-7.0. This shouldn't be the problem with organics. It looks like it is fading and you need to top dress it. Hopefully it works out for you.

The best pH is between 6,2 and 6,5.
But it is not enough tested pH of the medium, but the electrical conductivity is very important too!
At the same time advisable to know the feeding history, because most of the time happens something overfeeding.

I think the OP said his reading said the soil PH was ABOVE 7.0 and that makes sense to me. Your plants are showing an Iron deficiency, this is most common w/ a high ph (usually 8.0 +).

1st thing, raise your lights. Iron deficiency also causes light sensitivity. DL actually takes a while to buffer your soil appropriately, so you want to adjust using your water and adding some iron (botanicare cal-mag+ has Fe in it) and nitrogen to speed up the process. It will take a while to fix, but it will eventually.

I had a similar problem. All my plants were fine except one that was totally lime green from the top. They all had a ph of 6.7. Thought it needed more nitrogen, I gave it more but that didn't change a thing. I transplanted it and it came back to its green color. Just my 2 cents hope it helps.

So what are some of the best ways to bring the super soil back to a better PH range? I did let the supersoil cook for 3-1/2 months so my thought was that this should have given the Dolomite Lime plenty of time to work, and for the other ingredients to break down. My pots are 5 gallon, and the plants are not too big yet so if I were to do a flush with say 6.0 ph water they would be very wet for a long period which may be just as detrimental. Thoughts and ideas to get the soil ph back in line?

really interested if anyone has a diagnosis for the op on this...

Yeah Geekmike already did