Why is this yellowing? Autopots system running. Temp and humidity on point 75°-80° and 50-55 RH, HLG 600r lights. PH 6.0-6.3

[Lstangel64]

Did you remove the plants from the Autopot setup and hand flush the plants from the top with your EC feed?

You should calibrate your pH pen once a week. Chemistry labs calibrate pH pens every single time before use because they need to the hundredth accuracy. To the tenth is fine for our purposes, so once a week.

My step-by-step would have been:

1) Dip the pH pen into 7.0 calibration/reference solution - if it reads anything close to 7.0, then pH wasn't the problem; if it reads something like 7.5 or higher (or 6.0 or lower), then you had a lockout due to pH being off.
In that case:
- Calibrate the pen and take an EC reading of the res
- Fix res pH and flush the plant with EC feed until what comes out the bottom in runoff EC is the same as the EC you are flushing through from the top (usually 3x the volume of the pot)

2) If the pen was fine, then I would have taken EC feed and flushed the plant from the top and caught the first 8oz or so of runoff into a clean container and measured the EC. If the EC was far higher than what the EC of the res, then you had a lockout due to salt build up.
In that case:
- Flush the plant with EC feed until what comes out the bottom in runoff EC is the same as the EC you are flushing through from the top

3) If the runoff EC of the flush was within reason compared to the EC of the res (within 0.4 EC), then the plant is a heavy feeder and needs more food. Being that you have several deficiencies that appeared at once, it's most likely due to a lockout and the plant can't access the food already available to it.

Coco/perlite with synthetic nutes is fairly straight-forward to figure out if you do a step-by-step process of elimination from easiest step on. It's usually the pH being off or a salt build up.

The nice thing is once it's fixed, you'll get immediate results due to the substrate basically being hydroponics. That said, those shitty looking leaves are always going to look shitty, so don't expect that to change - look at the new growth for health and then begin to remove those shitty leaves because bugs love sick plants and go for the sick leaves first.

I did top feed them before filling the tank up with water.

 

[ec121]

I did top feed them before filling the tank up with water.

Did you check the runoff EC? That will tell you what's up.

Did you flush the plant until the runoff EC is the same as the EC feed (i.e., run several gallons of feed through the top)?

 

[Star Dog]

Did you check the runoff EC? That will tell you what's up.

Did you flush the plant until the runoff EC is the same as the EC feed (i.e., run several gallons of feed through the top)?

There's not any need to rinse it down the plants starving there's not enough nutrient, if it was burnt/over fed then yes I'd agree with rinsing it.

 

[ec121]

There's not any need to rinse it down the plants starving there's not enough nutrient, if it was burnt/over fed then yes I'd agree with rinsing it.

Yes, it is starving, but it most likely is starving due to a nutrient lockout. He didn't mention what his pH pen was when he checked it via reference solution (or if he even checked it before calibrating nor told us how long it's been since he calibrated his pen) so the exact cause of the lockout is unknown.

If it's a lockout, then you can give it as much nutrients as you want and it will still not access the nutrients and the deficiencies will only get worse until the lockout is corrected. Because the exact cause is not known, a nutrient flush is the safest option to get the root zone back in check asap. If it was already in check, then it will do no harm because in coco you never flush with just water.

If you want the EC to be 1.6 @ 5.8pH, then you flush it with 1.6EC @ 5.8pH feed until the entire root zone is 1.6EC & 5.8pH - now it's ready to rock again. If you don't feel there was enough food, then you can flush it with 2.0EC @ 5.8pH until the root zone is now 2.0EC @ 5.8pH. All you're doing is ensuring 100% that the root zone is the correct EC and pH.

This is one of the problems with bottom feeding coco. When you top feed coco to runoff everyday, it pushes the salts out and keeps the EC balanced day-to-day and you never need to flush (so long as you keep tabs of your runoff EC so you can make appropriate adjustments to your feed as necessary).

 

[Star Dog]

Yes, it is starving, but it most likely is starving due to a nutrient lockout. He didn't mention what his pH pen was when he checked it via reference solution (or if he even checked it before calibrating nor told us how long it's been since he calibrated his pen) so the exact cause of the lockout is unknown.

If it's a lockout, then you can give it as much nutrients as you want and it will still not access the nutrients and the deficiencies will only get worse until the lockout is corrected. Because the exact cause is not known, a nutrient flush is the safest option to get the root zone back in check asap. If it was already in check, then it will do no harm because in coco you never flush with just water.

If you want the EC to be 1.6 @ 5.8pH, then you flush it with 1.6EC @ 5.8pH feed until the entire root zone is 1.6EC & 5.8pH - now it's ready to rock again. If you don't feel there was enough food, then you can flush it with 2.0EC @ 5.8pH until the root zone is now 2.0EC @ 5.8pH. All you're doing is ensuring 100% that the root zone is the correct EC and pH.

This is one of the problems with bottom feeding coco. When you top feed coco to runoff everyday, it pushes the salts out and keeps the EC balanced day-to-day and you never need to flush (so long as you keep tabs of your runoff EC so you can make appropriate adjustments to your feed each day as necessary).

Looking at the plant its hungry and not displaying any signs of lock out to warrant rinsing, ph doesn't cause that ime, I think ph in general is over rated, I'm not suggesting it doesn't matter but it doesn't cause what the op has.

I'm familiar with bottom feeding I've never had any problems with it, I've never ever had to flush any it's no different to blu mats and the like.

Eta...if I was trying to flush medium to 1.5ec I'd use 0.8 to do it then feed 1.5ec last.

 

[ec121]

Looking at the plant its hungry and not displaying any signs of lock out to warrant rinsing, ph doesn't cause that ime I think ph is over, I'm not suggesting it doesn't matter but it doesn't cause what the op has.

Plants looking hungry with a number of deficiencies is the sign of a lockout in hydroponics.

Out of range pH is the #1 cause of nutrient lockout.

I never said rinse. Rinsing would strip all the medium of everything and you don't want to do that ever.

I'm familiar with bottom feeding I've never had any problems with it, I've never ever had to flush any it's no different to blu mats and the like.

Do you grow in soil or in coco with synthetic nutes?

 

[ec121]

Eta...if I was trying to flush medium to 1.5ec I'd use 0.8 to do it then feed 1.5ec last.

Sure. I just tell new growers to use the 1.5 the whole way to be safe as this will ensure the entire medium is saturated at 1.5.

 

[Star Dog]

Plants looking hungry with a number of deficiencies is the sign of a lockout in hydroponics.

Out of range pH is the #1 cause of nutrient lockout.

I never said rinse. Rinsing would strip all the medium of everything and you don't want to do that ever.



Do you grow in soil or in coco with synthetic nutes?

Lock out is caused by accumulated salts with over feeding not under feeding.

I use coco dtw and bottom feeding with canna a+b and ionic one part.

 

[ec121]

Lock out is caused by accumulated salts with over feeding not under feeding.

Absolutely, and also by having a consistently out of range pH. You can also get lockout by top feeding the correct EC without runoff and this will cause salts to accumulate. Runoff each feeding pushes salts out of the medium as you go.

 

[Star Dog]

Absolutely, and also by having a consistently out of range pH. You can also get lockout by top feeding the correct EC without runoff and this will cause salts to accumulate. Runoff each feeding pushes salts out of the medium as you go.

I've never seen plants issues like that caused with ph, it would need to be seriously out.

 

[ec121]

I've never seen plants issues like that caused with ph, it would need to be seriously out.

Well, we both agree it needs more food. My first response was post #2 in which I said, "You have a number of deficiencies. It needs more food." However, as more info became known, my opinion on the cause of why it is not getting enough food changed.

Using GH Flora Trio (that's what I use) at an EC of 1.6 in veg, I have never seen a plant have that many and as severe deficiencies. I don't even hit 1.6EC in flower and have no deficiencies running the ratios of (M:G:B) 1:1:1 early veg; 2:3:1 mid-late veg; 1:1:1 transition (higher EC than early veg), and 2:1:3 in flower.

This is why I suggested to dip the pen in 7.0 reference solution to see how close the pen is. If the pen is fine, then pull the pots out and top feed to runoff and check the runoff. If the runoff is fine, then it's a very heavy feeder. It would take all of 5 minutes to do both of these and verify what the issue is.

 

[Lstangel64]

I did top feed them before filling the tank up with water.

I woke up the other day and for giggles I decided to check my resevoir. The temp was sitting at 82° and PH was at 6.7. SMH. Since then I've corrected both and been monitoring it now. That's probably what was wrong !

 

[GreezzyGuy]

How are they doing ? how does the new growth look

 

[fatigues]

Assuming your pH meter is correct...

This is the problem. Your pH is very NOT fine; you just think it is.

The problem with growing in coir in autopots is that your pH in your rez is different from your pH at the bottom of the pot -- and that's different as well in your coir.

Your pH in autopots rises in the bottom of the pot -- and rises further still in the coir as water is removed and salts remain.

If your rez pH is 6.1,the bottom of your pots is flirting with 6.5 (at least) and the pH in your coir itself is 6.6+ and it's getting worse as the salt residue builds up in your coir.

And that's why you have deficiencies. Your plant is experiencing pH lockout as the pH in coir goes above 6.5, Yes, that's why you are particularly nitrogen deficient. If your plants were getting the nutes directly from the rez, they would be okay. But they aren't. In between the Rez and your roots are system lines, a copper disk, and a bunch of coir, perlite (and perhaps 1 to 1.5" of hydroton if you have that at the bottom of your pot, too -and hydroton is alkaline and will further increase pH). So they aren't getting the pH of the water in the rez. What they get is significantly higher than that in terms of pH.

What you are experiencing here is a frequent problem when growing in coir and autopots and leads to a lot of lost grows in flower as people get frustrated and the system seems to be resisting them. It's common AF, to be perfectly honest.

This is probably too late to help you, but for others who see this thread, this is what you do to fix it:

A - Make sure your pH pen is quality kit and is accurate. You can skimp on EC meters if you like -- but not on your pH pen. That needs to be spot on. It will cost you some $$ for a decent pen/meter.

THEN....

1 - dump all the water in your Rez and your pots;
2- Flush your coco from the top down with 4 liters of RO water each. Measure the pH and EC of your runoff. You need to get the EC runoff down to .3, your pH should be very close to the pH of your RO. If it isn't, repeat the flush with 1l of RO water each time until your EC plummets and you are running more or less clear in terms of pH by the time it hits the tip of the roots in the coir.

When you've got that stabilized on all four plants, reconnect your autopots and put fresh nutes in there. Set your rez pH to between 5.5 and 5.7. Do not let it go higher than 5.8 in the rez. Stay on top of it.

The base of your pots will creep up to 6.0/6.1. Your coir will be higher still than that and you will not be able to directly measure it without expensive equipment, but it should remain under 6.4. That will prevent nute lockout.

This is the problem with autopots and coir. The only way to deal with it is stay on top of it, keep your pH in the rez between 5.5 and 5.7 and your EC should stay between 1.3 and 1.7, assuming you are using RO water as a base (as you should be if you are growing in hydroponics - which IS what you are doing, after all). What your plants get, though higher than that, will still be under 6.5.

Note: if you are running an airstone in your rez, that will increase the pH of your rez over time even further. You need to watch this daily. By the same measure, if you run airstones in the bottom of your autopot, this will have the same effect in the coir, increasing pH a little bit more. Address this by erring on the side of caution in your rez and keeping pH there at 5.5, never higher than 5.7.