Can I accurately test new soil to see what the runoff PH is?

Long story short I am 2/3 of the way through my first grow and am having a huge problem with my Fox Farm Ocean Forest soil being too acidic. I am getting runoff PH of 5.5. I had to do a 15 gallon flush to get it to a runoff PH of 6.2. Today I watered with 2 more tablespoons of dolomite lime (for a total of 4 now) and water PH’d to 7.0 and I got runoff PH of 6.0. I am really pissed about this as Ocean Forest is supposed to be PH’d to 6.4. I had also added about 25% perlite which is supposed to be around 7.0 to 7.5 PH.

I still have some of the soil in the bag and am wondering if I can put it in a clean pot, water it to runoff and test the runoff to obtain an accurate PH reading? I am not sure if this will work because you can’t accurately PH plain water and I don’t really want to waste my nutes for a test run.

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Someone else posted a similar problem. They must have had a bad run on some product.
I think he flushed it out. Took like 90 gallons if I remember.

I’m having the same issue with FFOF on a grow I’m almost 4 weeks into. Sorry I don’t have any answers, but I want to see if there are any.
Set to watch

Wow, it took me almost 4 hours to do the 15 gal flush. I can’t even imagine 90!

That sucks other people are having the same problem, but I’m glad it’s not just me. I sent a message to Fox Farm directly to see what they have to say. It would be nice if they at least gave me a coupon or something.

A lot of people here successfully use Fox Farms, but I see post after post like this where it is an issue. Search for organic soil recipe if you are an organic person, or use Pro-Mix with GH Flora trio or Jack’s. Simple / foolproof.

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@dbrn32 This is the post I started about the Ocean Forest acidity issue. Looks like I’m not alone.

You can do a slurry test to see what it is right out of the bag.
Mix equal volumes of soil and distilled water. (such as 1 cup of each)
Shake it up and let it sit for 15 minutes and then strain out the water, like with cheesecloth or coffee filter and check the pH. I would be interested to see what it measures.
Youtube has many videos about slurry tests. Some say wait 24 hrs, but 15 min is sufficient.

Thanks man. I do have distilled water and coffee filters. I am going to go do that right now. My guess, PH of around 4.0. Hang tight.

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Run a slurry test instead. Put a cup of soil in a jar, cover completely with distilled water (must be distilled or RO water). Mix well and let sit for at least 30 minutes. Stain it through a coffee filter into a small container and then take you PH and PPM readings. It is a PITA to have to deal with that.


I did a slurry test, 12oz FFOF + 12oz distilled water = 1030 ppm & 5.83 ph

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@Mmchugh42 @Spiney_norman @beardless Here’s a dumb question. How the hell do I get the coffee filter off the top of my measuring cup without it sliding down into the cup and dumping soil back into my filtered water? I am currently on my third attempt and have the filter taped to the top of the measuring cup with painters tape. LOL.

I placed a filter in between two solo cups with drain holes. Held doubled solo cups over a container and poured slurry in.

Take a cup of new soil in a container and add a cup of distilled water. Let stand for 15 minutes then test the PH. That’s a slurry test and IMO more accurate than runoff.

Can i just test the “mud” or does it have to be strained? Trying to do this is kicking my butt.

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If it’s dilute enough dip that probe in and rinse off when done. It’s dead easy. If too ‘muddy’ add some more distilled as it instantly will adopt the native PH of test soil.

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I borrow my wife’s single cup drip coffee maker that uses the cone shaped filters. She like the earthy flavor of her next cup


@Spiney_norman @Mmchugh42 @beardless @Myfriendis410 @Reticence
Yup, I got a shit bag of soil. My slurry results are PH 5.3 and TDS 1924.

I’m constantly washing my hands when I touch this soil. I’m afraid of the bat poop!

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Man the ph is really messed up. My last slurry was 6.89 and tds of 2007. How far along are they? Any chance of moving up to a larger container with different soil. You would need to let them really dry out first so the root ball isn’t damaged.