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

I know every thing that I have harvested (autos so far) most of the upper leaves are in pretty rough shape by the time I cut her down. Browned out and dry. Do what you can to see it through.

Do you think this is from the light? Dbrn32 thought perhaps my light was too close but I am at the recommended 18" from top of plant. I am afraid if I raise it my lower buds won’t get enough light.

Are you using FF nutrients.

Don’t be pissed at the soil. This far in, most mediums start to acidify. That pH that is guaranteed is its starting pH. After months of growing, microbes and chemical processes tend to acidify the soil.

I recommend slurry testing.

Are you talking RO/Distilled? Tap water pHs just fine.

No, I was talking about tap water. I respect that everyone on here has some valuable experience they are willing to share with the rest of us. However, the general consensus is that it is not possible to accurately PH tap water. I can put my digital PH tester into tap water and get a reading but I have no idea if it is accurate.

I am about to create a new post regarding a reply I got from Fox Farm customer service. I will tag you.

I did do a slurry test. Results are in this post. They were not good. PH 5.3.

@smokysmurf that’s my grow. It was 90 gallon but between 9 plants. It took the better part of the day. For what it’s worth, after the flush; I have seen EXPLOSIVE growth. They are 17 days old today and I’m happy. They just got their first haircut this morning.

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That is incorrect info. Distilled and RO, yes. Not tap water. There is no arguing about this fact. :grinning:

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I’m a first time grower and learning every day but when the majority tell me you can’t PH plain water I tend to believe them. If you say I can that is great. Sometimes I don’t know what to believe because there are so many different answers to the same question.

No majority is telling you that anywhere, I promise. You may be misreading info.

There are a lot of newer (and older) growers who may be giving incorrect advice. Definitely vet who you take advice from. :grinning:


Just for future reference:

You cannot accurately pH RO or Distilled water because there aren’t enough ions to facilitate ion exchange.

In tap water, which contains many different chemicals, there are lots of ions, which allows for more potential cation exchange, which is what pH measures (Hydrogen exchange, specifically).


I use tap and PH just fine. My tap is generally 5.4 “well water” and adjusts to 6.5 easily.


How does TDS or PPM affect the ability to PH tap water? My tap water is around 45 PPM. I do remember specifically a few people telling me I won’t get accurate PH reading with PPM so low.

Think of pH like a party. It measures how much social interaction there might be with our buddy Hydrogen. If the party isn’t attended by anyone (RO/Distilled water), Hydrogen won’t have anybody to talk to, so there will be zero social interaction. If the party is filled with all sorts of people (Tap water), Hydrogen will interact like a social butterfly.


That’s exactly it! TDS is what sets RO/Distilled from tap. That number tells me your tap must be filtered. That’s incredibly low. Most tap water is not that low.

So, you are generalizing an issue but it’s specific to your own tap water. See the problem?

So yes, your tap water is too low. :grinning:

I’ve heard this too and I’ve been told that it is a normal run off with FFOF I hope you hear back from them

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My tap water isn’t filtered. In fact I use a Britta pitcher for my drinking water and it tests at 30 PPM. I am in NC which definitely has the best tap water of any place I have lived.

I get what you’re saying about generalizing an issue specific to my tap water but I have had many other users say you can’t PH plain water regardless of PPM. They sell digital PPM testers to test tap water so it must work, right? I never knew growing weed would be so complicated. LOL.

I will tag you on the response from Fox Farm.