Phosphoric acid in pH down harmful?

S

Steveolevi

420 Member
Hi. My plant shave been suffering with what I think is too high pH. Green has been fading out over time. I flushed 5 days ago and now my EC is around 1.4
My problem: My tap water is at 8.4 pH, and I bring it down to 6.5 with 20+ drops of pH down (Phosphoric acid) I'm in flower now. I check my runoff and it never goes below 7.1 pH. Ive adjusted the pH of water going in, but I'm afraid too much messing around with the pH to dial it in would be harmful. Is it normal for pH of runoff to be higher that pH of water going in? I'm in water-only supersoil and Ive heard that soil has "buffering properties"
 
You flushed supersoil? like organic soil?
Is that a good idea? you just got rid of the whole microbiome in the soil no wonder she's going yellow.
What are you using? Nute wise? ah nothing only water? well then you just flushed the nutes away..
I don't EC or PH or flush at all with organics.
If you need 20 drops of ph- to take the water from 8,4 to 6,5 it might be very hard water? that could also lead to grow & flowering problems.
When do you ph the solution?
 
OK...
1.You flushed supersoil? like organic soil?
Yes. The soil sells itself as "Water only". There all kinds of amendments int he soil. MY EC was at 7.7 and things were looking yellow. After flsuh my EC is around 1.2uS
2. I don't knwow if it is a good idea or not. This is why I'm asking questions
3. I use pH's (6.5) water to flushand then the last round is pH'd and Calmag added. Maybe I dont need calmag because the water is so hard.
4. I thought that using ph- made with Nitric acid would be good during Veg, and then I thought to switch to pH- made with Phosphoric acid during flower. Do you see my thinking?
I'm also concerned that too much phosphoric acid would be bad for the plants.
5. pH the solution before every wateringand check runoff everytime. I just can't seem to get runoff below pH7.0
 
Ah right.. I did have two bottles of Ph- in the dwc days, indeed the flowering was done with Phosophoric acid but that just breaks down in phosphates which are P nutrients. So you get added P for flowering whilst with the Nitric Acid you get added N for vegging.

Yeah I kinda wouldn't? you're not feeding salt based nutrients or were suffering a lockout or overfeeding? then there's no need to flush. Feeding through supersoil you create a microbiome that feeds the plant.. washing it away is probably a bad idea.

I do worry about the Tap water though.. as that's high and if you need to add lots of PH- means it's probably pretty hard.
Don't know how many plants you do but I just get spring water for my plants indoor as I just do 1 or 2. everything in it is on the bottle,it's also mineral rich but my plants are way way happier than with tap, Ph is 7,2 but I don't adjust as growing in soil in organics can take a wide range 5 to 8.

Do you air out your tap water? you need to leave it out a night before use, that should already drop the PH and more importantly air out chlorine.
 
Thanks alot! I'm pivoting my thoughts to maybe root problems. I water every 3 - 4 days, but try to rely on lifting pot weight rather than calendar. Stunted growth and yellowing. I'll send a photo when I get a chance. Thanks again
 
Steveolevi said:
I flushed 5 days ago and now my EC is around 1.4
Click to expand...
Over the past several years many soil gardeners have stopped recommending doing any type of "flush". Any decent dirt based soil mix, like the 'water only' types available at the stores, do not need a flushing. Flushing will remove much of the available nutrients and living micro-organisms in the mix.

My opinion is that 'water only' soils should be used in much larger pots than many growers try to get by with. The plant needs to be able to send roots out far and wide looking for available nutrients. Judging by the photo of the plants in your other thread my suggestion would be to use pots that are twice as large.

If you want to leave the plants in the same size pot you can consider using some additional nutrients when watering to boost the plants color and leaf size. That would be similar to what many of us do when we build a super-soil and then start to use one of the fertilizer brands to get even more out of the soil mix we are using.
 
Steveolevi said:
5. pH the solution before every wateringand check runoff everytime. I just can't seem to get runoff below pH7.0
Click to expand...
Having the run-off water be a different pH, and often higher, is not all that unusual. You would be surprised at the number of long time dirt soil mix growers who do not bother to measure the pH of the water in the saucer. They try to get the pH close to 6.3 and then let the soil do what it is supposed to do on its own.
 
SmokingWings said:
Flushing will remove much of the available nutrients and living micro-organisms in the mix.
Click to expand...
Wanted to add that even though the nutrients and micro-organisms have been flushed out it will still take a couple of days to replenish both to the same levels as before the "flushing".
 
Here is the current situation. My last watering was 6.5pH no nutes. I did topdress with worm castings at last watering yesterday hoping to replenish what I had washed out in the flush. I want to continue thi grow to the end without nutes. my runoff EC was aroung 1.4 maybe enough to getme through. This has become an expertiment rather that a harvest crop.

plant pH probs.jpg
 
Back
Top Bottom