DIY: pH Down - EASY!

Discussion in 'Do It Yourself' started by Enigma, Jan 13, 2010.


    Enigma Well-Known Member

    Hello, again, RIU!

    Thought this might be helpful, to everyone.


    (1) 2 L Bottle - Labeled as ACID - $1
    (1) Funnel - $1
    (1) Box of battery acid - Auto Part Store - $7
    (1) Set of measuring spoons - $1
    (1) 1 gal of distilled water - $1

    Grand Total: $11



    So use safety glasses, rubber gloves, and well ventilated areas.


    Always pour SMALL amounts of acid in LARGE amounts of water, SLOWLY!!!


    Fill the 2 L bottle with about 3/4 full with distilled water. This bottle should already be labeled for its intents and purposes.

    Prepare your battery acid and measuring spoons.

    With your measuring spoons mix the acid from the store with water in a 1:10 ratio. That is ONE part ACID, TEN parts WATER.

    For those lacking mathematical skill: ~180 mL of sulfuric acid in the 2 L bottle.

    This should bring the solution from 33% acid to 3.3% acid. Still, VERY DANGEROUS TO STORE AND HANDLE.

    Slowly pour the acid into the funnel, into the 2 L bottle making sure that the bottle doesn't over-heat. If it does, you are going to the hospital and forget any holiday pictures from now on.

    Once you have enough acid in the container to have the 10:1 ratio, fill the remaining volume with distilled water. Seal the lid and gently turn the bottle up-side down and back until fully mixed. Do this slowly.

    Now you should have a handle on mixing this stuff, and you should have enough for two years of constant use.



    StupidMoFo Active Member

    how about using a screw cap wine jug (key point) GLASS and not worry about having really thinned wall soda pop bottle break and own your ass. And since you're giving us instructions for diluting it why don't you tell us the exact amount of battery acid measured to put into 3/4th of a 2l bottle instead of a generic ratio

    tom__420 Well-Known Member

    3/4 of 2l is 1500ml
    1/10 of 1500ml is 150ml
    So that means you would need 150ml of battery acid for a 2l bottle

    Enigma, do you know the dosage rates for this concoction? Like how much to add to adjust the pH lets say .5 or is this just a copy and paste from somewhere else?

    Enigma Well-Known Member

    Thanks for slamming my proven DIY. It is easy enough for a kid in high school chemistry class to mix this stuff.. so I don't see the issue.

    Oh BTW, this is pro shit here.

    I find it silly to hold your hand when it comes to math. If you can't figure out a simple 10:1 ratio using 2 L as your volume.. you are lost to me.

    You will need ~180 mL of sulfuric acid to achieve at 1:10 ratio in a 2 L container.

    20 mL of this 3.3% sulfuric acid solution should drop the pH of one gallon of distilled water 2 points (pH of 7 to a pH of 5). If you are using tap water your results will differ.

    Honestly, what the hell is your problem? I give you a tried and true method, used before we were born, with a pro tutorial and I get slammed with this shit?

    This right here makes me think twice before helping you little punkz.


    33° WeedMason

    33° WeedMason Member

    pro shit... hehe

    SickSadLittleWorld Well-Known Member

    Great DIY!

    Using this method, I should never have to buy pH down again. With 40 gals of water to adjust every week, this will save some serious cash. +rep.

    BigBudBalls Well-Known Member

    pH down? Typically I need up. Most nutes I've used plummet the pH.
    (The almighty Fox Farms comes to mind)

    Enigma Well-Known Member

    BigBugBalls.. I have something special for you!

    I'll post another DIY after I get off work. It will be listed in my sig for easy clicking, as usual.

    This pH UP method will also last for ~2 years constant use. For the price, you can't knock it. Unless you're foolish.



    Tokey21 Member

    This is the same method that I use, except I use the battery acid at a 1:3 ratio with distilled water. Battery acid is specifically 33.53% pure, the remaining being distilled water already. At this rate, it usually takes me 7.5ml of this mix to drop 5 gal water from 7.1 (tap) to between 5.8 and 6.0 pH. I had mentioned this previously, but everyone told me I was nuts. The only downside, at least that I've heard, is that extra sulfur ions could build up, but I have never had that problem with hydro.
    Enigma likes this.

    Enigma Well-Known Member

    +rep for another lyon.

    With those concentrations you should be using an eye dropper. Which is what I would've posted, but not everyone is keen enough to handle something that powerful. Honestly, a 1:10 ratio is still pretty strong. I think the horticultural companies use something on the ring of 1:30.. but I could be wrong about one or two of them.

    Just think about how much water you are buying...

    Sulfur won't build up in the system, period.

    You might ask, why?

    The answer is simple. Plants need sulfur, it is a micro nutrient left out of a lot of fertilizer brands (except General Hydroponics). Plants will eat that shit up!

    I see absolutely no downside to this method, what-so-ever. In my mind, this is the only logical recourse to pH problems.

    I'm glad there are other enlightened minds still on this board.



    GreatwhiteNorth Global Moderator Staff Member

    Have you tried a product called "Acid magic"? It is a much safer alternative to hydrochloric acid and is intended to be used as a ph down (in pools and hot tubs) and can be poured full strength directly on bare skin with no ill effects.
    A 32 fl oz bottle cost me 8 bucks & with one decent grow finishing up I've used only about 8 oz of it.
    Check this vid out for a little enlightenment on this product.

    Not slamming you, just another option for my Green friends.
    mmjmon likes this.

    Enigma Well-Known Member

    I would never recommend HCl (hydrochloric acid) for use in horticulture. Plants need sulfur, why not give it to them?

    What does this "Acid Magic" contain?

    I won't use anything unless I know what is in it.



    mizcreant Member

    I have mixed emotions about using something as caustic as some of these replies. I empathize with you about the feedback your getting. Seems if people don't like an idea they could just not use it, but everything I learn is valuable, whether it gets put to use, or not. maybe one day you won't be able to go into the hydro store and buy a (ridiculous priced) bottle of ph up/down. maybe someday you'll NEED to use your brain, instead of payign others to think for you, and then paying them inordinate amounts of $ for it.
    I don't know if I would use this, I will think about it though, and thanks for posting. I think you made the hazards, and precautions clear enough. ppl just gotta use their brains, and many times, we al fail to do so. Just MHO

    cowboylogic Well-Known Member

    Why not just use vinager? Safe with no mixing.
    bigboyfly713 likes this.

    hitman40 Member

    I found a product for 15.00 a gallon at home depot called sikadur concrete cleaner & etch. MSDS sheet says 25-35 weight per volume phosphoric acid. The lable actually says phosphoric acid and nitric acid and water. Anyone ever try this a few drops and it lowers my 20 gallon res from 7.5 too 5.8.


    Enigma Well-Known Member

    Not a bad find, I will have to check that out.


    Skunk Monk

    Skunk Monk Well-Known Member

    this is crazy I think Im going to have to do this, do they sell the battery acid at walmart

    Enigma Well-Known Member

    They might, check near the smaller batteries for ATV's and motorcycles. Those batteries usually need to be filled and charged.

    I do know that any Auto Parts store will have this.

    Advance had it for some where circa $7.



    basher420 Member

    Great info for people on a budget and those sick of following the over-priced nute herd =)

    thanks dude!

    Enigma Well-Known Member

    Don't forget to +rep where it applies!


    That 5hit and basher420 like this.

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