PH problems all of a sudden!

Hey guys, when i first started growing, i played around with PHing of water. My water comes out of the tap at 8. When using PH down, ir was comical the small amount that it took to get to 6.5. Im talking like a gnats tear! Anyways, @bob31 was coaching me on using my nutes and testing PPM the past couple of days. I wanted to start nutes tomorrow, so i have been experimenting getting the measurements and PH correct. I finally got a grasp on nutes and ppms and today i about lost my mind! I bet i mixed 10 sep gallons of water with 1/4 1/2 and full strength nutes. Finally got PPMs in range as per feed schedule and once again @bob31 coaching. I go to test PH and it is high. I break out my huge bottle of PH down (the same one that i figured would last me decades seeing how small a drop works) and do my usual tiniest half a drop. Check PH… didnt budge. Tiny bit more… nothing. Almost the entire bottle later… 7 runs of nute mixing and i finally get the PH in 6.5 range. Go to check PPM… oh you know, no big deal at 2500ppm!!! Is it possible the seal on PH down was not tight and it lost its potency… causing me to use more and throw PPM in astronomical ranges!!!
@Countryboyjvd1971 @Covertgrower @Screwauger @SmoknGranny @Oldstoner @Donaldj


@VelcroThumb are you cleansing the meter with distilled water between all readings??

Just add some fresh lemon juice your pH will drop :slight_smile: I bet it’s cheaper than pH down!

I’d set up a control to see if meter is bad or not.

@HighDesertFarmer yep. I actually thought the distilled water might have been affecting it. I still think the PH down went bad. Like i was saying earlier, it literally took like .10ML to get 2 gal of 8ph water to 6.5. Thats barely a drop! Now its taking over 8ml to get it to barely budge. But it is also affecting PPM, which i have a different meter for

The solution n shouldn’t be random like that. Shake the bottle and try again? The .10 to 8ml diff is a huge one. Something up with either meter or ph down. No way you actually need that much.

Distilled water shouldn’t harm meter really. It helps wash the sensor of solids.

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Im gonna try lemon juice and see if i can get some calibration powder somewhere local

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Also curious if you just dropped some drops in and took readings or agitated water and distributed ph down in water.

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Always shake and agitate

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Im assuming if i just put them in and took a reading, then the meter would show extremely low and not roughly where PH of water was pre drops

Interesting @VelcroThumb

Usually when I use nutes, the ph either stays the same or goes down. (Depending on the type of nutes) GH stays the same or close and FF Nutes goes down to 5.8

Anyway in my situation it takes 1 drop per point of ph per gallon of water. 7.2 out of the tap. let it rest for 48 hours to evap the chloramine and check the pH 7.2 add 7 drops of down. Cap the jug, shake good and test. Exactly 6.5

Raising the pH is another thing. It normally takes 6 droppers of pH Up to go from 5.8 to 6.5

I also only mix up my nutes as I use them.

I’m not sure what is going on there with you, but sounds like your meter is having issues. Do you have 7.0 calibration fluid?

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I think mine calls for 6.86 fluid

Calibration fluid only come 4.0 and 7.0 that I know of

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Im thinking either the meter or the PH down got spoiled… might have been left open

I check the calibration of my meter at least once a week with the 7.0

I’ve never had an issue like that but you are right it’s one or the other!


I know bob31 has been guiding you. But maybe this will help you out.


Fertilizers PPM

To discover the ppm of your fertilizer mix, you will require being able to gauge grams
and liters. Come across at the nutrient 3 numbers written on the side of a fertilizer
package, these are the percentage substances of the nutrients in the fertilizer. Each
one gram of that fertili
zer in to one liter of water, this will give 10 ppm per percentage point of the given

Example a 20-20-20 nutrient gives (10 ppm x 20) or 200 ppm of every nutrient for each
gram in a one liter of water.


Grams of fertilizer per liter = A/B
A = your desired ppm
B = 10 ppm x the % of nutrient in mix or your ppm = C x B
B = 10 ppm x the % of nutrient in mix
C = gram of fertilizer per litter.

So to make create a 200 ppm to 100 ppm to 200 ppm NPK mix utilizing a 13-0-44
ratio of potassium nitrate, a 12-62-0 ratio of monoamonium phosphate, and a
33-0-0 ratio of ammonium nitrate you would work in reverse from your single
P and K basis (it makes it the simplest in this case), and create up the N at
the finish. I have rounded values to the nearest 0.1 g for the following. You
would utilize 0.5 g of potassium nitrate about 200 ppm/910ppm x 44k and 0.2 g
of mono-ammonium phosphate at about 100ppm/(10ppm x 62P) in one liter.

Fertilizers PPM

This would provide you 89 ppm N (10ppm x 13N x 0.5g + 10 ppm x 12 N X0.3g),
124 ppm P (10ppm x 62 P x 0.2), and 220 ppm k (10ppm x 44k 0.5g). 111 ppm is
necessary to elevate the N to 200 ppm level, so we can utilize 0.3g of the
ammonium nitrate (111 ppm/ (10 ppm x33N) to take us up to complete. The
concrete mixture would give away a 188 ppm N, 124 ppm P, 220 ppm K mixture
in one liter of water.

To obtain more accuracy, you require combining big batch or getting an
improved range. You would require to make 10 liter set of the over with
a range that is only precise to the gram. If you blend your own fertilizer,
you can regulate your N basis to meet up your ph requirements, rather than
relying on adding acid or base, which is good. This works for formulating
hydro mixes, as well as for us soil farmers.


This is exactly what happens with me, also using GH PH Down. I, too, don’t need very much to drop PH. In veg, where I am putting in far fewer nutes, I usually need 2.5ml (after the nutes are added - I’m using half of what GH recommends for their 3-part) to lower from 6.3ish to 5.8ish - that’s 2.5ml for 4 gallons of water. Sometimes even then I need to add a ml or so of GH PH Up after it sits for a bit.

I broke down and bought a more reliable PH meter - I had the cheap yellow probe kind a lot of people get and the thing constantly needed to be calibrated. My new one is much easier to calibrate, and I store it with a storage solution every single time and am just maintaining better. It’s ease of use was worth the extra scratch.

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First off the fact ph is hard to adjust after adding nutrients is no surprise ppm effects how stable ph is something I say all the time to people growing in hydro. Though usually nutrients themselves tend to drop ph some when you say it took lots to adjust ph was it 30ml? or a cup? ph down is acid so evaporating off water would only make it stronger and when I think of ph adjusting and ppm it is almost exponential it’s relation to ppm.
What surprises me more is that your nutrients didn’t lower ph?
when setting ppm I check before nutes after nutes then after ph adjustment so as to determine roughly what percentage of ppm is nutes


@VelcroThumb I store my ph meter in calibration solution :wink: which I change every other week I turn on meter before testing mix if it doesn’t read 6.9-7.1 I calibrate it. Since it is stored in 7 ph all the time the .1 variable can be evaporative or contamination so if it isn’t reading close to 7 I swap solution then calibrate
This is actually part of my daily checklist ph meters are caps off sitting in measuring cup I make sure solution is over probe levels every day and top off as needed this way instant I turn on meter I know it is reading correctly :wink: Storage solution at a neutral ph will not harm meter and keeps them moist which most will tell you is if they dry they die

Neutral ph water with nothing else will be easy to move with ph up or down. Once you start adding minerals, they will exert their own influence and a larger amount will be needed to effect any changes in ph as a result.

On a side note, raising ph with baking soda will apparently give an abnormally high tds value.

Citric acid is what I use. I have a quart jar full and it gets pretty comical trying to ph a small amount with THAT: one crystal or two? lol

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I prefer AN’s new ph down highly concentrated but still think liquid ph adjusters are the way to go because easily measured with syringe

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@Donaldj I finally broke down and bought the GH up and down. Using a pipette is way easier.