Need to raise ph of soil in flowering...again

Just wanted to see if I can get some advice with this. My plants are 1 week into flowering and 6 weeks old from sprout. They’ve been in 3 gal pots of straight FFOF for almost 4 weeks now, giving it nothing but distilled water and cal mag (1 tsp/gal) every watering.

So as usual with FFOF my runoff ph is coming out at around 5.2, plants overall still look good (newer growth) but many of the fan leaves are showing signs of deficiency and it looks like this grow it gonna end up like the last one, dead because of a ph lockout.

I have some dolomite lime but I know it’s slow acting, is there a better way to raise the soil ph and fix this? (Flushing probably isn’t a good option since I haven’t even fed nutes yet and the runoff ppms are coming out at around 600).

Thinking the newer growth only looks ok because it’s pulling nutes out of the other fan leaves because it’s already locked out, is this possible?

bump, help plz

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Sounds good - here’s the info (and pics):

  • Strain: White Widow photos from ILGM

  • Method: Soil (Ocean Forest, nothing added)

-Vessels: 3 gal plastic pots

-Ph: ph going in around 6.8, coming out at 5.2.

-PPM of water solution: haven’t fed nutes yet but I feed 200 PPM of distilled water and cal mag every watering. Runoff ppm is at around 600.

-Indoor grow

  • LED lights (SpiderFarmer SF2000)

-Temps: consistent at 75 degrees both day and night

-Humidity: around 30% (I know it’s low)

-Ventilation system: AC Infinity inline fan + oscillating fan inside tent

CO2: probably not as much as I could, but yes

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How much and how often do you water? Possibly root bound. Can you remove one from pot and check roots?

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I don’t think it’s a good idea to transplant again since they are 1 week into flowering…I water once every 4 days and only when they completely dry out, I think the issue is soil ph but I’m not sure…what I do know is that this is the last time I’m using Ocean Forest, I don’t know how people use this soil and keep their ph above 5.5 but I read somewhere that as the organic matter decomposes the soil acidity rises…I wanna use dolomite lime but idk if it will be too late

Try finely ground Oyster shell. I have Never used it but others do.

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I’ve heard that works as a buffer or something as well as the dolomite. Surprised this stuff isn’t talked about more when it comes to FFOF, then against I seem to be the only one using straight ocean forest and not mixing it with anything.


I use bicarbonate of soda to raise my pH up and it’s instant. Baking soda is the same stuff. Works well for me :sunglasses:

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I heard stuff like baking soda only temporarily raises the ph, then it drops back down eventually and you’ll have to flush out all the salts. I believe it’s the same thing if you were to flush with really alkaline water, it’s a temporary fix then the ph drops down again. This happened to me in my last grow, had a runoff ph of 4.9, flushed with gallons of 7.6 ph tap water until it was at 5.6…next watering it went back down to 4.9 (had a runoff ppm of like 80 ppm too)

I’m no expert but the way I understand it through my research and experiences, your soil ph will be whatever it wants to be…meaning that you can do things to temporarily alter the ph, but it will always buffer back to where it wants to be anyway. That’s why dolomite lime appears to be the answer - it’s the only thing that will PERMANENTLY raise your ph and keep it within a certain range no matter what happens…and I believe it’s because it acts as a “buffer” meaning it’s constantly keeping your ph within a certain range no matter what you put in it.

It feels unfair that I gotta deal with this stuff as a beginner and I’ve lost my first few grows because of it, but I guess that’s the curse you take on when using the infamous FFOF.

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Yep you’re 100% right in what you’re saying but as a lot of our grows are short lived, in pots, a quick fix is all we need to get us through the next phase of our grow. Now, if it was in my garden I wouldn’t dream of using baking soda it would be lime all the way as a longer term fix would be required. It really depends on what your long term strategy is.

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I hear ya. If I was close to finishing I’d try the baking soda method. But I’m only 1 week into flowering and these things will be in these pots for at least another 7-8 weeks most likely so lime it is…I know it takes 2-3 weeks to start working but I’m just hoping it kicks in sooner rather than later. I know I’m just ranting at this point but Ocean Forest has failed me and that makes me sad. I heard other peat-based soils like Happy Frog have dolomite lime already added in them but it appears that Ocean Forest doesn’t have any sort of ph buffer that comes with it…strange.

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I feel your pain. It’s difficult when you buy something for a particular purpose only to find that it’s not fit for that purpose, even though, by design it should be :face_with_symbols_over_mouth:


I know this doesn’t help your issue any but not knowing exactly what comes in pre mixed soils or is this bag going to be the same as last, is the reason I use coco. I know there is nothing in it when I start and it only has what I give it! I have never used Fox Farm personally although some people love it.


nice I didn’t actually know that about coco. I also hate how every bag of ocean forest I buy seems to be radically different from each other, I never thought about trying coco but if it has that kind of consistency then it might be worth trying

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