pH assistance required - promix / soilless medium

GP Rust

Member
Hey all. I have searched everywhere and can find no diffinitive answer to my question.
There is a mountain load of informatoin on the internet about pH, but wow does it vary (as usual internet) and nothing really as specific as I need to know. I'm not sure if what I'm asking is a stupid question, but this is my first time doing soilless medium and I have never had to worry about pH before (I have only grown outdoors).

Basically my question is:

If you test the run off, after watering with a solution of 5 pH, and the pH is too high (7.3).
Does that mean I must run even lower pH water? ie. 3.5 gets it to 6.9 run off, which is still too high.


My story / thoughts:

I am testing this using a styrofoam cup with promix and leca (clay) balls at the bottom.
I think there could be something wrong with how I am conducting the experiment, since it surely cannot be possible if i water with a pH of 3.5 to only get 6.9 runoff.

I did not dry the medium out between tests. So when i watered at 5 and the ph was 7.3, i continued to test new waters at lower pH untill arriving at 3.5 water --> runoff: 6.9. Is this result inaccurate, because there was water of varying pH present in the medium? [I collected the run-off in clean containers].

I feel like watering your plant with 3.5ph would be crazy, and am too scared to do it to my 2 seeds that are germinating now [in styrofoam cups]. They both just poped out the promix, forming their first 2 circular leaves and I need to know what pH to water my plants and ideally what the pH run-off can / should be.

I have gathered some information and these are the "ideas" have I have come to:

1). I have read that when people have too high / low pH in SOIL then they just keep watering at a lower / higher ph (but not as drastic as 3.5). They would for example continue to water with a pH of 5.5 (if their runoff was 7) so that their pH slowly drops in the long run.

2) Some people mention stabilising the pH of your medium before using it, some do this for promix as well, but some say it is nonsense. I don't particularly see the value in soaking your medium in water to get it to a lower pH. I feel the loss in nutritional value would be worse than the slight benefit of having an immediately "perfect" pH. I feel like the slow correction (mentioned in 1) is the right way to go. But am so indecisive becuase of the hoards of information that I have read. (PS. I am OCD as fuuuk - not the best characteristic for a grower :D)

3) Some say run-off itself is innacurate, but I do consistently get similar results (then again from NOT drying out the medium before re-testing, therefore contaminating the result (i think).

Thanks for any assistance that you guys can provide me. I am a first time grower and value all the criticism / help that can be provided.

Peace!
Mr. GER
 

MichiganMedGrower

Well-Known Member
Pro mix suggests watering with un adjusted tap water for the first week while the mix is new.

They say the lime needs that time to begin to buffer.

If I use the pour through method to check the ph of a new bail it always comes out acidic. And in a week it was always in the low 6's.

However the company warns to check to see if the mix is over-limed before using as well.

They have a learning center on the PT Horticulture website. Tons of great info geared toward Greenhouse crop growing but very helpful.
 

MichiganMedGrower

Well-Known Member
^^^BINGO^^^

Also, testing run off is the pH of the run off and not the pH of the pot contents.

You can get different readings depending on how damp the media is.
Testing pour through runoff is to detect trends in rising or lowering ph or ec to manage the Grow. Not to think you have a perfect in time reading that you can adjust immediately with the next watering.

It is commonly used in greenhouse management.

I hope you aren't agreeing to instruct to just always ph all inputs to 6 for everyone. That would surely acidify my pots in no time.
 

MichiganMedGrower

Well-Known Member
I used to play with Happy Frog now I use pro mix with fish powder once/botanicure pure gro for my cheap win in veg
I forgot about happy frog. I started with that. It also tested fine for ph.

But it was a cheap mix that compacted way too easy and had tons of uncomposted sticks and crap in it.

I found a chunk of wood from a piece of furniture or something in a bag.

They do say it is their budget mix.
 

Dr. Who

Well-Known Member
Testing pour through runoff is to detect trends in rising or lowering ph or ec to manage the Grow. Not to think you have a perfect in time reading that you can adjust immediately with the next watering.

It is commonly used in greenhouse management.

I hope you aren't agreeing to instruct to just always ph all inputs to 6 for everyone. That would surely acidify my pots in no time.
Oh I understand the Greenhouse part..The old German did it, and was pretty good at it.....I found other things to be far more accurate.

Like my Hanna soil pH meter....I got the greenhouse to spring for their own, once they saw that accurate and instant made for better plants in the long run...

Peat acidifies in time on it's own.....I don't like soilless for the media's faults.......Not a big fan of hydro and won't go back to that at all anymore. Soil, real soil......

As peat based soilless goes. For the the most part, the plants not in the media long enough for problems - IF it was properly limed and your not growing "trees"......A 4 month run is not a big problem......Having a Ca/Mg solution around is good advise....One that is Cal Carb based - Better buffer.
 

MichiganMedGrower

Well-Known Member
Oh I understand the Greenhouse part..The old German did it, and was pretty good at it.....I found other things to be far more accurate.

Like my Hanna soil pH meter....I got the greenhouse to spring for their own, once they saw that accurate and instant made for better plants in the long run...

Peat acidifies in time on it's own.....I don't like soilless for the media's faults.......Not a big fan of hydro and won't go back to that at all anymore. Soil, real soil......

As peat based soilless goes. For the the most part, the plants not in the media long enough for problems - IF it was properly limed and your not growing "trees"......A 4 month run is not a big problem......Having a Ca/Mg solution around is good advise....One that is Cal Carb based - Better buffer.
What old German?
 

GP Rust

Member
thanks for the advice guys.

i think my conclusion is that I need to chill the f*** out. I get way too OCD about these things.

I'm just gonna water at around 5.5 ~ 6 and hope for the best! If i see signs then I'll test my run off.

I also might give pots a gallon of 6ph water (as suggested above) before transplant.

Blessit!
Mr. GER
 

dandyrandy

Well-Known Member
thanks for the advice guys.

i think my conclusion is that I need to chill the f*** out. I get way too OCD about these things.

I'm just gonna water at around 5.5 ~ 6 and hope for the best! If i see signs then I'll test my run off.

I also might give pots a gallon of 6ph water (as suggested above) before transplant.

Blessit!
Mr. GER
Just don't over fertilize. Be one with the plant.:peace:
 

Dr. Who

Well-Known Member
I forgot about happy frog. I started with that. It also tested fine for ph.

But it was a cheap mix that compacted way too easy and had tons of uncomposted sticks and crap in it.

I found a chunk of wood from a piece of furniture or something in a bag.

They do say it is their budget mix.

I suggest you try Potters Gold - Built here in our state....GOOD STUFF! Nice 30 day feeder - well balanced and a shit ton of living bio's. More diverse then FF soils.
 
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