The best way to raise soil PH in week 4 of flower?

My soil PH is way to low. I'm in week 4 of flower. What's the best way to raise my soil PH substantially? I have PH up and I have been feeding my plants nutes with a PH of 6.8 but it does not seem to be raising my soil PH at all. Any thoughts?

My thoughts are how do you know the pH of your soil.

What kind of problems are you having with the plant?

I have a bluelab soil ph pen and my plants are yellowing. They seem to be lacking calcium and magnesium

A picture would help, and what does your pH pen tell you. What EC are you feeding at? Have you checked runoff EC and if so what is it.

If you have a buildup of nutrients in your soil it's probably time to leech that soil with some plain water until the runoff EC drops. And after it dries stop overfeeding.

Ph pen says 5.2. I do not have a ppm or ec pen. I definitely don't have any bugs. The pics I believe show a cal/mag deficiency in the leaves

The potting soil I have always had a low ph right from the start. When I first got the soil I did not have the soil pen and did not adjust the soils PH.

Certainly looks like mag rust and/or an absorption issue. Ok so if your soil pen says its low you can assume that is correct. I also assume you've been giving them cal/mag and if that's not helping then ph is definitely out of range & you need to act now. Adding liquid ph up will do nothing. You can either hydrate some dolomite lime by bubbling it for 6 hrs or adding it directly as a top dressing either of which should help. But first be sure your plants are not in too small a pot before doing this; transplanting during bloom is a pain but if your plants are root bound a transfer to some fresh ph balanced mix will also do the trick. If they have not filled out the containers they are in I would bubble some lime for a couple hours & add it in. It won't dissolve but you've got to get it down to the root zone to work somehow & bubbling it can help disperse it into the rhizosphere somewhat when you pour it on. Top dressing takes longer but is also an ez ph up fix.
Next time when you pot up your next set of plants add some oyster flour to your mix; it helps regulate ph at the root zone & works better than lime but it's gotta be near roots to work.

I have not been using Cal/mag but I just got some and I'm going to start using it now.Thank you very much Richard Drysift your info is very helpful!

I dont think there is any quick way to change soils ph, its not hydro and i blame leds for all the bad soil advice recently!

Magnesium is an element that helps plants absorb the others; it will help but if your ph is low it probably won't permanently fix your problem. I would top dress with a little lime; really should help but no it's not fast; could take a couple weeks to see results. I add soft rock phosphate to my mix globally when I recycle the root balls. It's very good source of mag but takes like a year to become available to the plants. If you are using RO or distilled/reclaimed water it has zero magnesium; that is why sometimes I still need to add liquid cal mag so there's always a fast source available to plants especially in mid bloom when they need a lot.

Kingrow1 said:

I dont think there is any quick way to change soils ph, its not hydro and i blame leds for all the bad soil advice recently!

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Alotta peeps don't realize that what you pay for in quality lighting is the proper spectrum and that most bag soil has very little available mag. Only quick way to fix soil ph is to transplant to fresh balanced mix.

Richard Drysift said:

Alotta peeps don't realize that what you pay for in quality lighting is the proper spectrum and that most bag soil has very little available mag. Only quick way to fix soil ph is to transplant to fresh balanced mix.

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A decent soil fert has mag but no cal to compliment the lime imo.