Lowering the pH of my water


#1

Is it true that white vinegar added to water lowers the water’s pH?

I know the water I will be using will have a pH of 9.2 after filtering.
I know I want to lower that to 6.0-6.5 in the safest way possible for my plant.

How do I do that, without spending a lot of money? If white vinegar works and is the best/cheapest way, then how many ml’s of white vinegar per Liter of water would lower my water pH to an ideal range? Thank you. Good luck growers.

If it’s of any difference plant to plant, I’ll be growing one of
Robert’s feminized White Widow plants.


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#2

Pure sulfuric acid would work better and is more stable. You can by this as a battery refill at a auto-parts store like O’rieley or autozone, etc. This is pure sulfuric acid and very strong but relatively safe. It doesn’t have any lead or anything bad for you or your plants in it yet as it has never been out in a battery with the lead plates yet.


Identify problem marijuana leaves
#3

Well that link answered half of my question. I still need to know how much sulfuric acid to use to lower a gallon or a liter of water with a pH content of 8.2 to ideal growing conditions for White Widow 30% Sativa 70% indica. Thanks.


#4

It will depend. You are going to have to remove, say a 1/4 to half cup to a cup of water from a gallon jug filled with your water. Add the sulfuric acid at maybe a 1/4 to half teaspoon, only about 2 - 3 ml, put the cap back on and mix thoroughly. Be careful for splashes, it is a good idea to wear eye protection when working with the sulfuric acid or any commercial “pH down” or phosphoric acid etc…

After a few minutes check the pH of your new mixture. You might even need to do it drop by drop, a teaspoon might be too much. If the new pH is way too low, split it up into a few other jugs, poor tap water about half way or more in each jug and then top the off from the freshly mixed batch, always add the stronger acidic mixture to a larger volume of less acidic water, not the other way around to prevent strong acidic fumes or “acid boiling”.

Depending on how hard your water is and exactly which minerals and how many of the Total Dissolved Solids(TDS/PPM/EC) of these minerals are in your water will determine how much of the sulfuric acid overall you’ll have to add to get to your desired pH.


#5

Thanks! I’ll put up my results when I get the rest of my lab in the mail this Weekend :lol:

P.S. I’m gonna use super soft water for these guys. Nothing but the purest water for my babies.


#6

Softened water? Or filtered/purified water? There is a difference and water that is softened with salt tablets is not good for your plants as the sodium content goes way up.


#7

I use sulfuric acid for both my greenhouse and MMJ PH down. I go to Auto parts stroe and but a “shop” size box. Very inexpensive. Ask for a battery refill kit if you only need a pint or so. Lasts a long time. Best to dilute it beyine what it comesd. use RO water , or distilled water to dilute . Hope this helps :slight_smile:


#8

That helped a bunch, i use vinegar but it doesnt last very long it seems, i adjust from 7,2 to 6.5 daily on 2 gals of nute in a 5 gal bucket at 950 ppm. Battery acid… Cant be any more dangerous than 35% H2O2, right? Lol. Im gonna try this. Tomorrow.


#9

Unused battery acid, yes, this stuff is pure sulfuric acid and totally safe when used safely. Used battery acid is no good, you don’t want the added lead, lol.

You will get much better stability and longer lasting results using sulfuric acid (battery acid) or phosphoric acid (the main ingredient in most commercial pH Down).

It could be argued that maybe this concentration of sulfuric acid is slightly more dangerous than 35% H2O2. Beware acid boiling. See above if you need further explanation.


#10

How would you go about using sulferic acid? Mix it with the water or what?


#11

Yes, exactly, the same way you’d use a commercial pH down, you would add it to your water, if your water has a high pH, you would add it as I described above.

You need the tools to know what the pH is in your water, you also need to know what it is after you mix in your nutrient (it can and will change the pH in the water, a lot of nutrient mixes are counting on you using tap, most drinking water and tap water is about 7 to 8 pH and of course in soil it should be 6.5 and in hydro 5.8pH and the nutrient mix might already be designed to bring it down from about a 7.5 down to the 6.5ish, but you can’t count on a nutrient mix keeping up with hard water with a high pH, unless maybe it is designed specifically for really hard water, and maybe not even then, you always should be monitoring the pH, in what you give to the plants and in the root zone/soil/reservoir)

The opposite can also happen, some soils or nutrients can become very low in pH on their own, or especially during vigorous growth period and/or especially during flower, and in this case you’ll need a pH up to add to your water and or nutrients and or soil or reservoir.


#12

sulfuric acid mix 1 cup acid .33 to a gallon of water how mush and how often should I use to maintain a 6.5 PH


#13

You use it the same way you would use any “pH down”. You use the new mixture to add a little at a time to your water so that it is at the correct pH before you water your plants with it or you add it to your nutrient mix to make sure the pH is in the correct range and close to your ideal target pH, 6.5 for soil and 5.8 for hydro, before feeding

Same thing for feeding. You need to be monitoring both the pH and the nutrient concentration of what you feed them as well as the pH of just the plain water. You also need to be aware of what is building up in your soil, so you don’t over feed them and to be sure the pH isn’t changing, it can have minerals build up that can make it more alkali than what you are feeding or watering it with, and also biological activity in the root zone and/or natural decomposition can sometimes make the root zone more acidic than what you are feeding it.

This is why you should be testing the soil or growing medium and/or the run-off after feeding/watering to give you an idea of what may be building up in the root zone as maybe being different than what you are feeding/watering them with.

If the nutrients or pH are way off, flushing with the correct pH water, with at least three times the volume of soil, should both flush excessive build up of of nutrient salt and bring the pH more towards the ideal. If need be, you can bring the pH of the water as low as 5.5 to make a more dramatic impact on a very high pH. And you can flush with more than 3 times the volume of soil if you need to, just be sure to let the soil nearly dry completely after all this harsh treatment to be sure the roots recover and don’t drown, before the next feeding with the recommended nutrient concentration for the stage of growth it is in.


#14

I am having a problem lowering my PH. I am using a Hanna Meter with fres batteries.
I use 4.01 and 7.0 to calibrate the machine. My tap water that I run through RO unit is usually around 7.1 or 7.2. You guys here have talked about adding drops to the water. I use 1 gallon of water and add the nutes. PH usually hasn’t changed. I then add seveal good splashes probably 1-2 ounces and it might only be lowered to 6.7 or 6.8. To get down to the 6.0 that is my target requires quite a bit of the PH down fluid. Any ideas why the PH is so hard to budge?


#15

have you checked your tdds ppm of your water out of RO unit? if you have some mineral left in water they will buffer ph many ro units put calcium back into water at last cycle as some minerals are good for people.