Entering week 6 flower - ph fluctuations

Hey everyone! I’ve been using this site for a lot of helpful info on my first grow so I figured I might as well join! Glad to be here!

Quick background info…I’m an experienced tomato grower among other vegetables and now that I’m working from home I needed something to offset the cabin fever. Why not try growing something I love?! A buddy gave me a few Northern Lights seeds in late July… I’ve been growing under 4 T5HO54 bulbs throughout veg…then…I noticed the depot had 26w GE HOLED 4K lights for 5.00 each on clearance. Plants actually responded better to these over the fluorescent throughout the rest of veg…Decided to switch to a vspectra p2500 at week 2 flower. Eased them to 16" at w4 up until now heading into week 6. Earlier this week they started to get really yellow even though my ph has been 6.5-6.8 . Did a soil test testing NPK amounts…N was very low with both…PK optimal. Work being slow I decided to try the most cost effective route initially with pretty much soil and nutes I already have. Kellog soil with amendments (pretty much same ingredients as ffo) and jacks all purpose and bloom. I hit em with a worm tea on Thursday and they seem to have responded quite well so far…leaves getting greener and overall bud health looking better. My road block is that I’ve checked ph at different areas of the soil at root level in my 5 g bags…there are major shifts in some areas vs others. 4.8 up to 6.8. Should I just let the tea do it’s thing and back off? Any suggestions? Thanks in advance. Being a noob I should’ve checked all over from the beginning!

Do you check your ppms? If theyre high then ur getting salt build up which will make soil more acidic and lower ur ph

And also letting it get real dry before watering can cause fluctuations too

I’ve got a meter headed to me. I’m thinking that’s probably it…high ppm and maybe even a combo with dried soil at the bottom of the 5 g bag. I was worried about root rot so much that I didn’t want to give them too much water…Uploading: 20201113_075145.jpg…

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Yea if you haven’t been checking ppms then its probably most definitely high ppms causing ph issues. Use ph’d plain water next watering and water till you have a bit of runoff. And never water while its still pretty damp. I use the lifting the pot method. When u water with runoff you lift it and basically when it feels way lighter than it was after a watering then u water again until runoff. As long as u let it about dry out u wont worry about over watering. Not getting runoff every time just causes the bottom roots to just sit in concentrated salts at the bottom

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Makes perfect sense. Thank you. I will definitely do that when they need water again and thank you for the tips on the weight, etc.

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Report back when u get ur tds/ppm meter and check the runoff. But dont water too soon while its still pretty wet

Alright. Ran the ppm test using ph’d water. Runoff came back fluctuating between 1278-1357 ppm.

Give it plain water next watering along with niw so u can wash some nutes out

Got it. Thank you