Low EC runoffs. Any advice greatly appreciated

My EC and pH runoffs has been unusually low.

Plants are day 16 in flower, well rooted, 5gal pots with 4 emitters per pot. Plants get watered twice per day until good runoff. RO water with 2ml/ gal CalMg. Growing with Plagron premium.

pH/ EC in - 6.1/ 2.0
Runoffs - 5.8/ 1.1-1.3

I've tried flushing massive amounts of full strength nutes through these pots and the Runoffs are stuck at 1.3.
Where are all these salts going?

Could a potassium, magnesium, or sulfur deficiently do something like this?

Is it possible the coco is binding to these nutrients?

Any advice would be greatly appreciated.

Do your plants express a deficiency? If not then only concern yourself with what goes IN, not what comes out. I took this advice early on. Deciphering runoff can be helpful sometimes, but still, the solution to a problem in coco is flushing with pH balanced nutrient solution. If that fails to bring about a positive change to your plant's health then other things need to be looked at like your coco source/age/additives, water source/chemistry, nutrients, environment etc.
And I don't run EC that high anymore. Plants don't need it IME, but each to their own.

As Dots stated above , runoff checks with coco are subjective at best since the medium holds onto X amounts to maintain it`s cation exchange capacity/CEC....but....It`s a start , and as long as the ph reads within proper parameters as in 5.5-6.3 , macro as well as micronutrients will be absorbed , and the EC is standing @ 1.3 cuz that`s all the plants are eating and it`s consistent too if you`ve run buncha juice through the containers as you say...….so.....

If you`re experiencing no deficiency symptoms , try feeding 1.2 in @ 5.8 PH and see what the runoff reads , but as long as you`re DTW with ample runoff you should be golden....I ran coco dtw for a decade and never went over 1/5 EC/750 ppms with dialed results consistently runnin Cal/Mag @ 5ml per gal Silicablast @ 5 ml per gal and SM-90 @ 5ml per gal....that`s it.........less is more believe it....anyways....Hope that helps....Good luck and.....

Peace.....DHF....

I suspect lower EC runoff is what you want and displays no major buildup is happening.

If the plants look happy don't play with it too much.

Is Plagron premium a typical salt based feed?

It sounds like you could pour 2.0 in the top, and 1.3 would come out the bottom, like it's a sieve?
That's not possible. The coco can only hold so much, and likely held it before you even purchased the stuff. Buffered..

There is something I'm not seeing here.
Perhaps get a jug of 2.0 and dump in a handful of coco. Stir. Wait. Stir. Check.

The plants look okay, but they're definitely missing something. Slight interveinal chlorosis, some general yellowing on the plants. Leaves aren't as green as they could be.

The whole thing is just...odd. Typically I would expect to see EC runoffs at least equal to what i'm putting in. For the runoff water to be .5 - .7 EC lower than whats going in seems almost impossible.

I'm also fighting low pH. I'm feeding at 6.0/6.1 and i'm getting 5.6 -5.7.

CaptinFunk said:

The plants look okay, but they're definitely missing something. Slight interveinal chlorosis, some general yellowing on the plants. Leaves aren't as green as they could be.

The whole thing is just...odd. Typically I would expect to see EC runoffs at least equal to what i'm putting in. For the runoff water to be .5 - .7 EC lower than whats going in seems almost impossible.

I'm also fighting low pH. I'm feeding at 6.0/6.1 and i'm getting 5.6 -5.7.

Click to expand...

Up your Cal/Mag to 5 ml per gal and the interveinal chlorosis and yellowing off should subside.....Drop your feed back down to 1.2 as suggested above and see where runoff ends up , but 5.6-5.7 is not "low ph" , it`s just a tad low for coco...…

You`re in mid stretch @ 10-11 days flower and your ph is dropping cuz the plants aren`t eating......try not to run too much liquid through the containers cuz you can overwater coco and affect the rootzone that will force the plants to stop eating so , back off on the feed and see if they perk up and green off....the Cal/Mag will help IF they`re eating ONLY , but it`ll also up the EC so adjust base nutes accordingly....Try feeding @ 5.8 ph and 1.2 ec and see what happens Bro.....can`t hurt.....anyways.....my 2 cents from all those yrs.....Good luck and …..

Peace.....DHF.....