[Brando_The_Commando]

pH rises naturally due to CO2 (carbonic acid) loss in solution. You stated you keep your water for at least 3 feedings. Some of that water is going to naturally evaporate and the carbonic acid with it, hence you’re seeing a rise in pH.

My water is around the same and I always pH it.

• This reply was modified 2 weeks, 6 days ago by  Brando_The_Commando.

[tommy]

Where can i read about this? Google is only giving me stuff about carbonic acid in carbonated water. I can leave a bucket out adjusted or not and 24 hours later the ph will be the exact same as what came out of the tap, why does it not rise higher than what comes out of the tap if i dont adjust it?

[jmystro]

Carbon in the air in the form of CO2 when mixed with water, creates carbonic acid. It’s a natural weak acid that helps dissolve limestone for example, releasing minerals. Using an air pump/stone in a high CO2 grow room environment will pump carbon in to your reservoir.

[tweetop]

Brando is correct. I struggle with similar issues. There is often magnesium carbonate, and or calcium carbonate in water. These are the main cause of ‘hardness’ and ‘total alkalinity’. When these are present the ph will drift up over time. I used some test strips to better understand what is in my well water. You can get a water report from your utility company. Those aren’t as detailed.

RO and distillation are the most effective ways to remove calcium carbonate. Most other filter types won’t. For this reason people blend RO with other water source 50:50 to reduce the concentration. Theoretically if you had the right concentration and proportion it wouldn’t drift or lock as much.

[jmystro]

Citric acid can be used to lower pH but as you’ve found out it’s not stable. Phosphoric acid (H3PO4) is a more useful acid found in most pH down products as it also becomes plant food as it breaks down.

[tommy]

So if i was to let my water sit out with an airstone for a couple extra days and then switch to phosphoric acid instead of citric that would give me the best case for what i can do with what i got at the tap without cutting it with ro?

[jmystro]

You can let it sit for a day without an air stone to allow chlorine to evaporate from your city water. Air stone will speed up process. If your city water has chloramines in it, then you’ll need an activated carbon filter to remove them.

[Peter Woitalla]

I just ph down with regular vinegar. The acid will also help break down carbonate nutrients into acetates that your plant can instantly drink it up as it needs rather than waiting on microbes to break off the carbon

[jmystro]

I try to advise against using carbon based sources for raising or lowering pH. In small amounts baking soda and acetic acid are fine. But I would never recommend using carbon based additives for pH on a large scale in reservoirs. Carbon creates solids and sludge.

[modudegrower]

My water from KCMO is like 10.2 pH straight out of the tap. Dude has said so many times on the show that he hasn’t heard of water being like 8-9 pH. Try 10+ mostly year round. Depending on nute mix sometimes it comes out in the sweet spot with no adjustment needed. But quite often it takes around a mL/gal of pH down to get down to 6.3-6.5 pH. Grow on!

[twistedcolas]

I live in south dakota we got 8.7 ph right out the tap I can believe this. Have you ever looked up what’s in it? Chloride and chlorine are both killers of microbes. There is a new one too chlorimide. Which is not able to be evaporated.

[jmystro]

Every water source on earth has a little chloride. Don’t go thinking you need to remove it or that it kills microbes. Chloride is an essential element required by plants. Your plants would die without it.

[tokez]

The goal is just to lower the chlorine levels so its not lethal to the microbes right?

[jmystro]

Correct.

[JD Nope]

That is wild. I’m on well water (300 ft well) and my ph runs 7.5-8.0. I use 2 teaspoons of pH down for 5 gal of water. It gets me to 6.5. I’ve done it so many times I don’t even “pH pen” it anymore. Once I got the pH right, my grows have been much healthier. Lots of genius help in here. Peace. Side bar: I’m using 3gal auto pots in my setup.

[twistedcolas]

Have you Try ascorbic acid instead(vitamin c tablet) roughly 50 milligrams to gal. That’s about a 10th of most tablets. Otherwise half a tablet to 5 gallons. It actually binds to and neutralizes chlorine chloramine chloride. Citric might be just bringing the ph down and not doing anything chemically. It could be doing something chemically and once it does it makes the citric acid able to be evaporated.

[denverdoggy]

Water pH is a proportion to temperature. Temperature increases and pH decreases.

• This reply was modified 2 weeks ago by  denverdoggy.

[farmville]

Don’t overthink it use some vinegar to ph down. The plant can metabolize it