using CO2 to control ph

Discussion in 'Hydroponics' started by Gen, Apr 1, 2006.

  1. Gen

    Gen Registered+

    I just found out this incredible thing today. Using CO2 to control ph. Mountainman talked about getting a controller to build a ph adjusting machine. Someone posting about using CO2 to control ph.

    Armed with my new soda club machine ($79 Edition 1) I was ready for the challenge. Today I measured tap water with CO2 and without CO2. The same with R/O water.
    Seltzer water is plain water injected with CO2. Here are my results.

    Tap water with CO2 5.4, 5.0, 5.0 5.1
    Tap water without CO2 7.1, 7.1 7.9 8.0

    R/O water with CO2 4.4, 4.4, 4.5, 4.5
    R/O water without CO2 8.0, 6.0, 8.2 8.3

    I injected CO2 till the machine farted. Serious folks. The machine makes a farting noise when no more CO2 can be injected into the water, but without the smell. Amazing. I used this same bottle of water all day and did not change the tap water sample or R/O sample during this experiment.

    There is an errant number in R/O without CO2 which might be due to ph meter error. I did check it three different times. I used the same ph meter throughout this experiment.

    CO2 stabilizes ph and brings it down and holds it steady. The hydroponics industry already knows this and is using this technology. Hence we have ph meters using CO2 to control ph.

    Look at the range at both tap water and R/O water with CO2. Remarkable, the CO2 holds it steady and when compared to the same type of water without CO2 you see the increase in ph.

    Look at the figures for tap and R/O water without CO2. The ph is very alkaline and the nutrients are not available at this ph level. Inject CO2 into water and look at the results. Lowered ph levels to perfect range for mj plants. ph 5.0-6.0. And so far pretty constant.

    Now we know why the ph steadily rises. The plants is using up CO2. So yes the roots do take up CO2. The whole plant is a CO2 consuming factory.

    So getting to the bottom line. CO2 does make a big difference. Maybe people can stop using dangerous chemicals (muriatic acid) to control ph and just use CO2 to bring ph down. I never felt good about giving my plants all that vinegar to control ph. If you poured straight vinegar on a plants root, it would die.
  2. HydroDynamics

    HydroDynamics Registered+

    Your idea is not revolutionary... people who have fish tanks (big ones) often use CO2 to adjust the PH. Normally they will bubble a small amount to keep it down. All it takes is on the order of 10 bubbles or so per minute through a special device that pushes the water down, while the bubbles go up (this desolvees the CO2 into the water, otherwise it would just bubble away). CO2 in water will not displace O2 But, if the O2 is kept up, like with a bubbler, so you can use both safely.

    I always suggest using a bubbler to add disolved O2 to the water no matter. Roots just love it :dance:

    Hope you enjoy keeping your PH adjusted with CO2 if you go that route. Personally, I go the chemical route. You can find a schematic of a PH adjuster using CO2 on the web by searching for it. If your good with a soldering iron, your almost there.
  3. turtle420

    turtle420 Banned

    Good info Gen! :)

    Interesting read... :)
  4. Gen

    Gen Registered+

    Thanks hydro, I knew people could do this because the meters are out thereto do this very thing. I think it's brilliant.

    Why do you prefer chemicals? Are they just easier.

    Thanks turtle.
  5. latewood

    latewood Banned

    I love people willing to take a chance to educate themselves
    as to the pros and cons of a concept.lw
  6. Gen

    Gen Registered+

    Thanks late. I've got an update. Hey, that rythmes.

    Alright down to business, first picture is roots on CO2 and lucas formula. Before my roots hated my cooking. They would just turn brown and rot. Then I found the lucas formula and my plants started cooking. Then I added CO2 to the water and boom they are estatic. Next picture is the top of the plant. I can't tell you how many happy roots I have now.

    Thanks a million guys. I am happy now.
  7. LIP

    LIP Banned

    "Alright down to business, first picture is roots on CO2 and lucas formula."

    I see no pics?
  8. knowledge

    knowledge Registered

    Hey Gen,

    I am hoping that i could get some of your results. I was looking to build a co2 pH controller. I am wondering if it is cost effective as well.
    I know if you already use co2 in the air then you should have all you need to make a co2 ph controller, along with some switches and meters. I use the Nitric acid and phoshoric acid as of now, but I to hate using corrosive chems for my roots on a constant basis.

    All the info I can get would be appeciated, thanks
  9. Gen

    Gen Registered+


    here are the pictures.

    Milwaukee sells a ph CO2 meter for $80.

    I have been very pleased with the results. I am only using CO2 in water and using that to adjust my ph. My ph stays closer to 6's and only once went into the 7.1 range. The roots are beautiful.

    How much acid do you need to use per gallon. When I was using vinegar I had to add alot to get ph down. I had to use alot of vinegar everytime I need to adjust ph and that was twice a day. Now I just pour seltzer water in the reservoir. The lowest ph reading I got from seltzer water was in the 4 range.

    The only bad part I can see is it dilutes your nutes. So I take out some water every couple of days.

    Attached Files:

  10. Zandor

    Zandor Registered+

    I used all that at one time to control my Ph as well. Now I only use Ph up and ph down from the hydro store and it's balanced better and I use way less then I ever have using Natural methods. The amount of nutrients (as long as your nutrients have buffers) you have in your res helps to keep the Ph in check as well. A 10 gal res will hold Ph better then a 5 gal res will; only because the nutrients have a buffer built in.

    I have a fish Ph kit from Milwaukee and even hooked up a CO² tank to it and it worked like a charm when I was out of town. Problem is it only controls the ph one way. There is a Ph up & down as well as a feeding machine but they cost about 2k.

    Even if you use lemons, vinegar or the Ph up & down the few drops you use will not dilute the nutrients. The PPM changes as the plants use up some nutrients and deposit back others.

    Just a little FYI
  11. Gen

    Gen Registered+

    Z, what do you do when you go on vacation?

    I have been using CO2 seltzer water to adjust ph and I find it easier than the other natural stuff. I only have a few plants so I just adjust a couple a times a day. Yesterday I didn't get to adjust a couple of plants. This morning their ph was at 6.2. Not bad. I should leave one plant and see how long till it gets to 7.

    It's good to hear you had to try different stuff Z. I was beginning to think you were born with the knowledge.
  12. Gen

    Gen Registered+

    I meant that as a compliment too.
  13. Zandor

    Zandor Registered+

    I have friends who come over and check them for me. I can set them up for about 10-12 day's with out touching them. But that depends on the cycle they are in. Early in veg and after the first week of flower I'm good to leave them for about 10-14 day's. Those are the slower periods where Ph is the most important and the nutrients are not as strong so you don't need to watch them as closely as other times in the cycle.

    My knowledge comes from many years of failure. With out failure you will not have true knowledge. "One must fall and get back up many times before he can learn to run faster." I also have a very extensive book collection, as well as the ability to learn from reading, then pushing and challenging what they said and seeing for my self. I had an opportunity in the early to mid 70’s to spend summers in Humboldt with friends. I spent several weeks helping them plant, care fore and then harvest many, many times.

    That was a very long time ago.
  14. knowledge

    knowledge Registered

    What chems are you using for the pH, I am using Nitrogen and phosphorus acids and bases, on low concentrations, I use about 3-6ml at a time, for a 50L res, to control pH, i looked at some pH up and down, but it does not say the chem, or chems used to do so.
    So If I read correctly you find that the pH up or down is better than co2. At least for your setup. And since you used co2 before, do you find it disappated into the air fast.

    And also I am not automated yet, so i have noticed that i need to adjust my pH every hour or so. Is this common.

    If I don't make sense please ask me to clarify.
  15. Zandor

    Zandor Registered+

    I have found the for ph Vita Grow brand has no coloring added as well as Mad Farmer brand but the GH Ph products work fine as well. They just color theirs so you don't use the wrong one. Earth Juice Natural crystallized Ph products are all organic.

    When I used lemon juice from the tree in the backyard and backing soda I adjusted my Ph 4 to 6 times a day. I tried the CO² tank for Ph control and that worked but only one way.

    When I switched to commercial pH products I only need to adjust the pH once or maybe twice a day. The commercial pH products seam to work better with the commercial nutrients then home remedies.
  16. Gen

    Gen Registered+

    I adjust ph once or twice a day. Once in the morning and once at night. The hydro stays around the 6's. Then I just dump more CO2 water. I've gotten pretty good at judging how much to add to drop it a few points. I use about a liter of seltzer water a day for the reservoirs. My roots are incredible and thick. I have about 4 gallons total of hydro water and nutes.

    Attached Files:

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