Using Vinegar To lower pH

Hi All,

This is an addition to my first grow journal which I just started, but I figured I would make a stand alone post since this is a whole topic on its own.

Link if you want to follow along.

I’m trying to keep my first grow relatively low budget, so I wanted to avoid pH up/down products and use something natural. After getting my pH/TDS pens, I went to work figuring out how to get my plants the right water once they’re growing.

My initial test of my water came out to 8.1/106 (pH/ppm). So obviously, I don’t have to worry about pH up. I did some research and vinegar came up as a pH down substitute, which sounded good to me since I have it in the house. After some more research (1, 2) I decided I needed to do some science. So here’s what I came up with. This is all with freshly calibrated pens which were rinsed with distilled water and dried after each measurement.

  • 1L of water straight from the tap - 8.1
  • Add ½ tsp of white vinegar - 5.6
  • Add 0.5L tap water - 6.0
  • Add 0.5L (2L total) tap water - 6.3 @ 2:10pm

Success! ½ tsp vinegar per 2L water (@8.1pH) = 6.3 pH. I double checked this and the initial calibration with the root farms ph test kit and it seems to line up (though it’s a colour solution so hard to nail down). One downfall of this method is people said the pH rises over time and their runoff goes up over the course of a day. Let’s test that.

  • @2:10pm - 6.3
  • @3:10pm - 6.53
  • @4:10pm - 6.66
  • @5:05pm - 6.7
  • @6:40pm - 6.7
  • @10:35pm - 7.0
  • @11:30am - 7.5
  • @2:45pm - 7.6

So, it appears to be true. Over the course of a day the pH went back up almost to where it was before. This leads me to 2 assumptions:

  1. If this method is to be used, it’s better to water with less water, more often, since the pH of the water is basically blocking nutrient uptake after ~24 hours.
  2. Since the pH rises, it’s better to start with a ph on the very lowest end of the recommendations, since the ph will rise and move across the whole spectrum of pH level and their associated nutrient uptake.

I would love to hear some feedback on this and my assumptions. Right now, this seems like my plan for the whole grow. Obviously there’s mention of other things like citric acid, etc but I don’t have access to those on hand. I’m sure I’m missing something that affects my assumptions so please, let the knowledge rain down! It’s what you folks do best.

Griff :v:

Keen to follow @Griff
Good luck. Just started my first grow and journal also, so much to learn.

I’m just learning, my first indoor grow. Isn’t there Ph stabilizer-type additives that would help keep the ph of your “vinegar” water ph more constant? That rise is pretty substantial

Sorry to see that few of the experts here gave took much interest in your persuit.
I have already attempted the use of ACV as I have been gardening for 28 years but in my maiden voyage in the medicinal herbaceous realm. I did not chart hourly but noticed next day numbers were back up around 7.2
I’ll continue to use in the AM