Compost Tea pH

Grow from Home DIY Do It Yourself
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Hello everyone!

I have been making compost tea for nearly every watering and am now entering flower phase with plants that seem healthy and happy.

I recently got an Apera pH/TDS meter and some pH Up/Down.

Should I be concerned with adjusting the pH of tea made with RO water when it’s around 7.5 after brewing?

I have added pH Down the last 2 brews to get to about 6.25 but am I killing off beneficial microbes by doing so?

Would using Citric acid make a difference from the Phosphoric acid in pH Down?

I’m growing with organic amended nutrients. Coast of Maine

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Citric acid makes a great pH down. It just so happens to be an important tricarboxylic acid critical to the Krebs cycle (energy source in all living plants/animals). It is also unique among all organic acids on earth in that it has THREE pKA’s (LOL, don’t worry, I won’t go there !!)

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Ok, I will use citric acid from here on out.

Is adjusting pH necessary when the tea is brewed at about 7.5?

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You know, when you brew teas you are dealing with a lot of organic substances…
They don’t behave at all like the inorganic acids most people are more familiar with…
My best guess is that they neutralize very quickly with a small amount of phosphoric acid…please tell me if that is correct???

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Yes, for 3 gallons of compost tea I use 1 ml. phosphoric acid and the pH drops from 7.54 to 6.13

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Yeah, that’s what I figured.
That being the case, I wouldn’t worry about pHing your tea at all…your soil microbes will acidify your tea quite quickly…

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I know from growing mushrooms for years that one way to pasteurize substrate is to shock microbes with a drastic swing in pH. For this I would be using very alkaline water to pasteurize straw.

I’m concerned that by adding the pH Down after brewing I am destroying colonies that I just grew.

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@TheMadFlascher Ok thank you so much for the advice. I will let nature take its course.

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As far as I know, that amount of phosphoric acid would have very little to no effect on your microbes.
In commercial agriculture, where large amounts of phosphate fertilizers may be used, I know phosphates can be tough on Mycorrhizal fungi.

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Good stuff guys…:+1:t3::+1:t3::v:t3:

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I always pH my feed before I add my microbes as I’ve been told phing after microbes will kill off microbes

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Great tip I’ll try it out then let you know if I notice any difference - I have traditionally phed the water after all additives and haven’t had many issues with either soil or hydro but I’m keen to experiment :blush: if there’s any noticeable differences I’ll report back and let you know :blush::kangaroo:

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I just made a pint of citric acid dissolved in reverse osmosis water and the pH is 1.35! :astonished:

I bet this pint lasts a long time. Way cheaper than buying pH Down formulas from different companies.

Viva Doria 100% Pure Citric Acid, Food Grade, Fine Grain, 2 lb (907 g) https://a.co/d/a3nacjF

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That’s it my friend.

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I’ve been following this for general guidance in formulating brews for compost tea.

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The only other hint I can give you is using potassium carbonate as a pH UP.
You’ll see a little cloudiness when you first add it to a low pH liquid…have no fear…it’s not precipitate, just tiny CO2 bubbles that will quickly gas off…

Bob

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I hope this doesn’t sound ridiculous, but would a shot of OJ in a hydroponic system do any harm or good as opposed to actual ph down?

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Well it would certainly bring the pH down but I’m not sure what effect the sugar would have. Someone else with Hydro experience would know.

This is my first run with cannabis but I’ve been growing things for about 20 years.

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Well, orange juice certainly is acidic and does contain citric acid.

Sugars are a little different animal. There’s a lot of Bro science out there believing that high additions of sugars or molasses will make the bud ‘sweeter’ !
In soil media grows, occasional applications of a complex carbohydrate (black strap molasses) are indeed effective at stimulating your microbe population, however, simple carbohydrates (sugars) really have no benefit at all…in fact over a longer period of time they will actually alter your microbe population, not in a GOOD way !

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Thanks… I use Molasses and was really glad u took the time for a response.

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