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Measuring Runoff TDS & pH?

infiniteJuan

New Member
re: Measuring Runoff TDS & pH?

Is there no viable information to be obtained from collecting such data? If so, why not?

I'm thinking that by measuring runoff numbers I can make better decisions on when/if I should flush, or water with just plain PH'd water for a time or two in order to get runoff numbers (PPM and PH) to a correct range, if it's going a bit off-kilter.

I'm noticing that my runoff on the current grow increases PPM as I feed without feeding just plain water and the PH ends up lower than that which has been going in. For instance, I'm feeding right around 550-650ppm and 5.8-5.9ph recently.. today the runoff PPM was close to 1000 and the PH was 5.5. The PPM has been steadily climbing over the last 4 or 5 feeds and I'm thinking I would like to knock that PPM number back down a bit and that PH number up. The plants seem quite healthy at the moment, but if I can, I'd like to head off any trouble at the pass. What do the expert/advanced growers think about any of this? Are there other resources I should be looking at?

I'd really appreciate some insight on this if anyone has any. Cheers.
 

Weaselcracker

Nug of the Year: 2016 - Member of the Month: Sept 2015, Nov 2016 - Nug of the Month: Oct 2016 - Plant of the Month: May 2016 - Photo of the Month: Nov 2020
re: Measuring Runoff TDS & pH?

Subbed to see what info comes up.
In a perfect situation I think ppm of the runoff would be zero as the plant would be fed and use exactly what it needs. Of course that's not going to happen. But high ppm runoff tells me I need- more runoff...
I find measuring the runoff to be kind of a rough guide at best, and extremely confusing at worst. Keeping in mind that whatever water you add (to achieve runoff with) is going to affect the ph and ppm of the runoff- it seems hard to get more than a general sense of what's actually going on in the pot.
Probably there are growers who use runoff measurements regularly and have a more consistent system than I do.
 

MickFoster

Well-Known Member
re: Measuring Runoff TDS & pH?

I have been growing in coco for years and I have never tested the run off for pH or tds. Never had a problem. Testing it will drive you nuts for no reason.
 

infiniteJuan

New Member
So then, in a case where I'm just starting to see what seems to be nutrient burn (pic below), what's my best course of action?

28246281405_b0ca6d6979_o1.jpg
 

Weaselcracker

Nug of the Year: 2016 - Member of the Month: Sept 2015, Nov 2016 - Nug of the Month: Oct 2016 - Plant of the Month: May 2016 - Photo of the Month: Nov 2020
Personally I would flush that plant, and test the runoff till it gets down below 300 or less. Then feed it at half strength, making sure to give it all the nutrients it needs. For example, don't forget to add calmag if you're using that- because you're potentially leaving the plant in a vulnerable way if you flush it and forget to add something back.
Another option is to leave it, don't feed it for a while and hope it uses up the excess nutrients. That may not work out though. It looks like it's had too much N, and plants don't use much N in flowering. The leaves are cupping- which could be from heat stress, or from the buildup of nutrient salts ( has the same effect of drying out the leaves).
Anyway- that's what I would do. I don't claim to be any sort of growing expert whatsoever.
 

infiniteJuan

New Member
Thanks for the input, WC. You sure are an expert compared to me! I have flushed twice with plain tap water (150ppm out of the tap) PHd to 5.8 (once last night, once this morning) and the runoff PPMs have gone from 1200ish ppm to 800ish ppms.
 

gr865

Well-Known Member
Flushing with just pH'ed h2o shocks the plant, IMHO. If I were going to flush, I would flush with maybe a lower ppm nute and pH'ed water.
If I were using 750 ppm solution @ 5.8 pH, I would flush with around 450 to 500 ppm of your regular nute program.
I have flushed soil, Perlite Hempys, and coco Hempys and all caused the plants to slow down if not stop growth for a period of time. I will not flush now unless something really gets out of wack, and then it will be with reduced nutes and proper pH.

And as far as testing runoff, I agree with Mr Foster, it will drive you crazy. Just make sure you ph and ppm's are good going in and don't worry about it unless you see a problem, which you shouldn't, by just being diligent.

Now this is coming from a guy who has had only one grow with no problems at all, but that grow was dialed in correctly. :51:
Now when I say problems, I only consider those that effect yield, everyone gets a little burn, over prunes, under waters/overwaters, and the such. It's mitigating those issues that save grows.
GR
 

infiniteJuan

New Member
Thanks for the input, gr865. What exactly would cause shock by using 150ppm tap water? It seems that if there is 1200-800ppm of runoff from 150ppm input, they have plenty of nutrients still available within the coco that they can utilize if they feel so inclined. Is this not the case? The highest ppm I have ever fed them is around 700ppm.
 

gr865

Well-Known Member
Thanks for the input, gr865. What exactly would cause shock by using 150ppm tap water? It seems that if there is 1200-800ppm of runoff from 150ppm input, they have plenty of nutrients still available within the coco that they can utilize if they feel so inclined. Is this not the case? The highest ppm I have ever fed them is around 700ppm.

I use RO water because my tap sucks big time, over 750 ppm. The RO I use is very very low ppm under 10. I would just not want to shock them with very little or no nutes and proper pH.
When I did flush it was like a shit load of water, say 2 to 3 gallons per gallon of post size. I was taking my ppm run off under 100, I believe that was the problem. After that, when I flushed it was with 400 ppm, ph 5.8 and would flush till runoff was between 400 and 500 ppm. Then get back on normal water/nute program.
I am no expert, just what I have observed in my grows.
GR
Good luck dude.
 
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