pH adjusting help

WHAT??? he is not here exactly when we demand it? Lmao

Until he tags in (why rush) i think safe thing is to just water with 5.8

Yeah, I’ll be back when I have time to properly read all the above and add comments that are more informed.

In the meantime, here is an article by Robert that might clear up some questions, and/or maybe bring up new questions:

Watering with pH 5.8 certainly won’t hurt, and if in soil-like/soilless media, flushing, the usual 3 times the voulme of soil with 5.8 pH water should mostly remedy things anyway.

Be back somewhat soon, certainly I should have an answer for you in less than 24 hours, can’t stay here 24 hours a day and it is getting late for me, if this doesn’t solve your problems.

I have an early day tomorrow, most week days for that matter, lol.



Thanks @MacGyverStoner, I got it from here

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Follow what he has just told you meanwhile if you have questions ill be here to answer them

Sounds like a plan… "I love it when a plan comes together"
H. Smith

Uhhh next question, where do babies come from? Oh wait that is a different forum :grin:

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Well I no longer trust my pH meter (too much variance even with new batteries and calibrations.

The best part is so far the Amazon seller wont respond to warranty info request… Someone gonna get a bad review.

So I’ve been flushing with 5.8 (or as close as I can get) using the litmus fluid testing.

I got runoff flushed clear but so far is still testing in the 8’s.

Unless y’all say otherwise, ima give her a day to recover, flush more… Then replant in a bigger pot using just the sphagnum peat and perlite?

I did want to ask… I forgot to mention i have used a bit of diatomaceous earth…
Does that change any suggestions?

No that does not change any, give her a day to recovery if nothing transplant

That’s why I always have the drops as a backup to test my pH… I don’t care what , watercolor never lies… but meters will screw up on you every time … just my 2 cents… no matter even if I check my pH with my electric meter I always double-check it with the water drops which come with the ph up and down kit… which I believe is just basically iodine but I could be wrong…:v::sunglasses:

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OK, so here is my take after a thoughrough review:

OK, the above article is a great article by Robert. However, I personally do things a bit different, and I’ll explain why. I don’t like to use coffee filters, unless you have the “acid free” type. Many types of paper, because of the chemical bleaching to turn the paper fiber white, are actually quite acidic. And so this can obviously add acidity to your results, especially if you are only testing a small amount of soil. And so your pH is more likely closer to the 8.7, and the 5.9 might be a combination of the paper adding acidity and microbial action over 24 hours.

And so I would either be sure to have acid free paper filters, or actually use no filter at all. All that is really needed is after mixing the water and soil, and you don’t really need it to sit for 24 hours, an hour would be enough to give you a pretty accurate result, and by then the soil in the water should have settled completely to the bottom of the container you are using, after a very thorough mixing.

And then just use your pH and TDS probes to carefully dip into the top clear part of the water, for your measurement, no filter needed, no acidity added by non acid free paper.

And if you use the pH test drops as was mentioned, you can suck some of the clearish top water with an eye dropper, syringe, or something similar – to be added to the vial with the pH test drops to get your pH measurement.

Yes, agreed, you have too many things going on and actually are probably having a general nutrient burn/toxicity, and the 12-0-0 does mean you are likely to have the nitrogen in abundance on top of everything else.

I’m going to get a little technical, so bear with me, but it will all make sense when I’m done and you will better understand the differences.

pH 6.5

OK, here’s the rub. In general, yes 6.5 is the target pH for actual soil, this means all the things in real dirt, which will contain sand, which is basically crushed and eroded rock and organic matter. This will contain all kinds of minerals, like mostly quartz AKA, silicon dioxide, and mica, a form of silicate or phyllosilicate (vermiculite is also composed of this compound), aluminum, iron, and some other metals and minerals, and then there is the organic matter, which is primarily composed of, humic acid, saccharides (sugars), proteinaceous material (proteins), aromatic carbons (hydrocarbons), and some good old water.

pH 5.8

This is for hydroponics, i.e. water only, where there will be pretty much none of, or almost none of the above materials which have a buffering effect on nutrients.

And so most soilless media will fit in this category, like pure peat moss or coco coir, expanded clay pebbles, pure perlite, and rockwool/mineral wool.

Lightweight expanded clay pebbles, also known as LECA or hydroton, for the most part, is pretty much entirely inert and neutral in pH (that means pH 7.0). It is composed of mostly silicone dioxide, and some aluminum oxide, ferric oxide, and trace amounts of potassium oxide, calcium oxide, magnesium oxide, titanium dioxide, and sodium oxide.

Perlite is also chemically inert and so pH 7/neutral. It is composed of mostly silicon dioxide, some aluminium oxide, and trace amounts of sodium oxide, potassium oxide, iron oxide, magnesium oxide, and calcium oxide.

Rockwool/stone wool/mineral wool is composed of mostly silicium, calcium, aluminium, and magnesium. The pH of the mineral wool varies from being neutral to slightly alkaline. And for this reason it often needs to be pre-soaked or flushed with 5.8 pH’ed water to get it to a relatively neutral pH.

These being inert means it doesn’t really react with the water, so it won’t add anything to the water as far as nutrition for the plant is concerned. And it shouldn’t alter the pH very much.

However, under some extremely acidic conditions, some of the minerals and such mentioned may leech out and contribute to the hydroponic solution’s EC/TDS and potentially slightly alter the nutrient profile and pH, which might cause some problems, but if the hydro has become that acidic, you will probably already be having problems, and this leeching and breaking down of the media is most likely to happen with rockwool.

BTW, diatomaceous earth is also pretty much inert and neutral in pH, however, in some conditions, such as mixed in peat or coco core, this, rockwool and even perlite can act a little like lime as a slightly alkali buffering agent, adding mostly silicone to the hydro solution, if recirculating.

Silicone additives like Silica Blast and Armor Si have a similar slight buffering on the hydroponic nutrient solution.

OK, so with things that are inert, basically you are feeding your nutrient solution directly to the roots, no real significant buffers, no microbes really to process and change things. And so this is why you use 5.8pH.

Foliar spaying is not very different than hydro, as you are directly applying the solution to the leaves, again then you want pH 5.8pH.

With peat moss, it can be broken down by microbes and become acidic over time, and so you might want to have the nutrient’s pH slightly higher than 5.8pH, to balance that, say around 5.9-6.0. For example this is what is recommended by the manufacturer of Pro-Mix HP, which is pretty much entirely horticultural peat moss. And depending on your individual circumstances, you might want to even pH your nutrient solution as high as 6.2pH.

Coco coir doesn’t acidify as easily as peat moss, and so most recommend , if you use it pure, the standard 5.8pH for hydro in a inert substrate.

However, if you add earthworm castings and bloodmeal, to peat or coco, these thing can be used by microbes and be broken down to become more acidic, and so again, you want to use a pH somewhat higher, more like real soil/dirt, but as it isn’t totally like dirt, say between soilless and dirt’s pH, and put it about 6.2pH-6.3pH.

Certain potting mix soils have so many of these easily broken down organic compounds, you might actually want to even bring you pH slightly above 6.5, again to kind of counter and balance the acidification that will occur at the roots do to natural microbial activity. And so a pH of about 6.6-6.8 might work best for you.

Hope this all makes sense and clears things up, and happy growing,



Thank you for coming when,you got a minute @Macgyverstoner I appreciate it

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@MacGyverStoner and @peachfuzz… Lots if good info.
“Johnny 5 need input, Johnny 5 is alive”

Mac are you like a pro hortiCULTurist or something? Ha

Good news is a replacement pH meter is being shipped and yea I think verifying with the kool-aid? Litmus is a good idea.

So given the possible (individual conditions)…
In the end is it logical no matter the grow medium (for simple men like me) to say if your runoff water is at or near your pH goal… Then you should be good?

If not Always water/feed with your pH’d goal (5.8 for me) or water with the pH difference of goal +/- runoff

Example goal = 5.8
Runoff = 6.7
Water with = 4.9

Maybe y’all and @Majiktoker can Hail an uber and come over to help… I just got approved to drive for uber!

I think my replacement pH meter is working better, so I bumped this thread as I still need answers to pH math when runoff is out of range? (above)

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Great question, thanks

@Brocksamson, what are you trying to figure out with the numbers

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Ok so if my pH runoff goal is 5.8…do I always water with 5.8?

If no, how do I determine any adjusted numbers? (to correct the runoff)

Ok so, for example if you water with a 5.8 ph in a soilless medium and the run off comes out at say 7.0 and it comes out brown. Water with just a ph water of 5.8 until all run off comes out clear no color. If its brown that is a sign of a toxic build up or toxins your medium is holding in. Runoff is an essential process to Make sure nothing builds up.

That should correct it and if not you can always (worse case scenario) water with a ph of 4.6 until it comes out corrected thus making your runoff come out at 5.8.

If you have to use the worse case scenario, once your runoff comes out clear, you will want to correct that from 4.6 to 5.8 immediately before it makes your soil acidic and starts causing root problems. Make sence @Brocksamson

Otherwise if your goal is 5.8 in your medium (and of course if its soilless) than yes you would want to just water with a ph of 5.8 every time to prevent ph fluctuations, and that way you know your ph will always be correct


Yes, in hydro or a soilless medium, you always want to add at 5.8, always want to try and keep your pH at 5.8

Your target pH for hydro/soilless is 5.8pH. And for soil, the target pH is 6.5pH.

Broadly, for hydro/soiless you want the pH to stay between a 5.5 to 6.5 range. And for soil from 6.0 to 7.0 and for more precision, not much higher or lower than about 0.3 than the target pH and so between 5.5 to 6.1 for hydro, and 6.2 to 6.8 for soil.

In a soil or soilless medium, it is ok to put in the the proper target pH in the top, and it is fine if the runoff coming out the bottom is a little lower, but not much lower. It is only when the runoff is coming out way different than what went in is when you need to worry and correct.

You can correct similarly to what @Majiktoker stated at the top of this question, by add a pH quite a bit lower or higher than your current pH to get it to the correct pH.[quote=“Majiktoker, post:15, topic:8900”]
If your raising .7 on ph for example water at 5.8 and comes out at 6.5, water with a 5.1 ph it should come out at 5.8. As for soils and hydro ph, yes @BrockSamson ph is the same for any form of hydro or soilless medium and all soils will have the same ph.
However, you want to avoid using a pH higher or lower than the max ranges, especially as root damage will occur at 5.4pH.

@BrockSamson TDS is total dissolved solids, and is measurement of nutrient fertility in the soil or nutrient solution. They do make soil probes that can be used in soil or soilless mixes like peat moss, but to test runoff, you use a EC meter, electrical conductivity meter, not that different than a digital ph meter, and these often show you a number that is supposed to represent the total dissolved solids in PPM, parts per million.

Hpe this helps clear things up, and happy growing,



@Majiktoker as usual you are majik… Exactly what I wanted to know. Looks like I was on the right road, right math.

(I’m bad at math, good to make sure)

How often do you check the runoff?


BTW @BrockSamson, I edited the above with more detail and for better clarity, so you might want to re-read it and notice the changes.



I only check my runoff when my plants have severe issues, in my opinion that is the only time I find it really necessary to do so otherwise it just makes more work for you to do in the end, others may have a different take on this so if they have an input remember to be open minded and consider other opinions about this @Brocksamson. :slight_smile:

Happy growings

Ps…@Macgyverstoner thank you for popping in with a more thorough explanation happy growings to you to