How Does Cal Mag Effect PH and PPM in Soil

Is there a correlation?

I don’t know about pH. It does affect PPM. It’s why I measure my input PPM before adding cal/mag.

You got it backwards ph affects everything, I’ve never had it crash or raise the ph if that’s what your asking.

That usually happens with regular nutrients and boosters. You could try to use humic/fulvic acids to help with that a bit… maybe it’s just me but I’ve found using it before adding the base nutrients I’m able to stabilize the ph.

I did

Dry cal
Dry mag
Dry maxi gro
Crashed ph to 4

Then I added acids

Dry cal
Dry mag
Dry humic
Dry fulvic
Dry maxi

Ph stayed stable up until maxi, dropped to just under 5 then raised back up.

Does that answer it?


I believe Cal-Mag is supposed to be neutral or very close too it. :face_with_monocle: :+1:


No not quite.

This is more of what I’m experiencing. After doing a flush with what I thought was 6.5 pH water earlier in the day mixed up some cal mag in my 5 gallon Reservoir and that night after watering my water came out at 7.0 on the dot. I let it go a couple days and let the pot dry out some. Did another watering with just pH water of 6.5, still coming out 7 .0.

Do I need to do another flush in PH reset or should I just keep watering with 6.5 pH water and will that bring it down?

I’ve read that cal-mag is supposed to pH levels from drastically spiking and I’m wondering if the Cal Mag is the reason why my pH is not changing even when running excess water through my pot.

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This is in direct relation to my grow journal here

You are quickly passing my level of knowledge. I don’t believe flushes will do much except strip your soils of goodness. I don’t think it is capable of ‘locking’ your pH at a given level. You could trial dropping the pH of your water and allow the Cal-Mag to use its apparent 0.5 pH bump to your advantage.
Hopefully others chime in and confirm or crush my theory - either way it will help you. :+1: :sunglasses:

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No problem and thank you. Feel free to follow my Grow Journal if you want.