Need Help Understanding My Nutrient Delivery Problems!

[curiousgrowth]

Hello all!

I have a nutrient delivery issue that I just can’t figure out, and need some help from you gurus!

Space:

3 x 3 x 6.5 tent
300L R- spec light
Cloudline T-4 ventilation fan with controller
Autopot watering system
Cloth 5 gal pot
Coco with 50/50 perlite
Little 3 amp heater
20” box fan
Temps: 78* light/heater on, 60* both off
Humidity: 75-55% veg to flower

Food:

Tap water: 7.4 pH/80-90 PPM
Sensi Coco
Advanced Nutrients Big Bud Coco
SLF-100 enzymes


Some History:

I’ve been using Autopots now for about a year and a half. I get around 5-8 oz of nice flower per harvest, with 3-4 oz of trim and small bud that goes into butter. I started out using General Hydroponics Floranova Grow and Bloom with decent results, then moved on to AN. In the first couple grows I used soil, then switched to coco. I recently stopped using Botanicare Cal-Mag+, but had been using it at near max recommended strength.

The Problem:

With both foods, I have had to feed at/or under half of the recommended food or the leaf tips start to burn.

I have a buddy who is growing using the same exact methods and materials (I supplied him and helped him set up) who is able to feed exactly as recommended on the bottle. He is using same food and cal mag, same lights, similar tent, same Autopot, same coco and perlite, same T4 at same settings. His reservoir PPM is around 2100, he sees zero burn, and the plant is a monster. Anything over 1000 and I get burned.

Water is the only difference in our setups. His tap is around 250 PPM, 8 pH. I have a couple suspicions as to what might be happening.

Suspicion #1:

Lack of trace minerals in my low PPM water is affecting the way the plant uptakes nutrients, causing lockout and deficiencies.

Suspicion #2:

Lack of calcium in my low PPM water is causing the nutrient uptake problem. I tried using the Botanicare, but didn’t really see any change other than adding more PPMs. I’m thinking calcium phosphate might be a better calcium than calcium nitrate?

I am still learning a lot about this stuff, and am by no means an expert. I am open to any ideas! Honestly, whatever is going on hasn’t prevented me from getting decent harvests. I used to think “half food” was my curse for having Autopot convenience. Now I see his grow and I’m a little jealous:)

Included are some pics of the tent setup and current grow. Lili is a Hawaiian x Purple Skunk cross at 5.5 weeks.
Advanced Nutrients
Advanced Nutrients
Advanced Nutrients
Advanced Nutrients
Advanced Nutrients
Advanced Nutrients
HLG

 

[curiousgrowth]

Suspicion #3:

Town water has something in it my plants don’t like, causing the lockout

 

[curiousgrowth]

Oh, and pH sits around 5.5-6

 

[RealizedReal000]

What’s the ph of your medium?

 

[curiousgrowth]

What’s the ph of your medium?

Not sure, I haven’t checked. I’ll go and figure that out.

 

[boomgagem]

Off the wall, but does he have a box fan sitting like that too? That could be drying the coco out faster causing fluctuations? Just a thought

 

[curiousgrowth]

Off the wall, but does he have a box fan sitting like that too? That could be drying the coco out faster causing fluctuations? Just a thought

He does, setup the same way. The coco feels damp all around the pot, doesn’t seem affected by the fan.

 

[Grownsince95]

That's also a big temp swing day and night. I would try temps in the 80-84° daytime and 70-74° at night. LED lights need higher room temps to get the leaf temps high enough to move enough water. That and some wind stress from the giant fan might be causing metabolism issues imo.

Just right off the bat the temps were a flag for me because 78° with 70%rh is going to cause some cal issues at least. And 18° night day difference is a little too much especially down to 60° f

 

[Grownsince95]

If you blow too much air on the underside of the leaves you will disturb the carbon dioxide flow in my opinion.. I like my air just above the canopy and strong enough to deflect off the walls and diffuse everywhere that's just my bro science opinion though.

 

[curiousgrowth]

Not sure, I haven’t checked. I’ll go and figure that out.

Coco pH comes out to 4.5

 

[Grownsince95]

Coco pH comes out to 4.5

That's measuring runoff? Waaaay too low

 

[curiousgrowth]

That's also a big temp swing day and night. I would try temps in the 80-84° daytime and 70-74° at night. LED lights need higher room temps to get the leaf temps high enough to move enough water. That and some wind stress from the giant fan might be causing metabolism issues imo.

Just right off the bat the temps were a flag for me because 78° with 70%rh is going to cause some cal issues at least. And 18° night day difference is a little too much especially down to 60° f

I would have trouble getting temps like that without a bigger heater. Tent gets closer to 63* at night, but still chilly. Basement in VT:/

 

[curiousgrowth]

That's measuring runoff? Waaaay too low

Slurry test taking some top soil and letting it sit in tap water for a bit then measuring pH of water

 

[boomgagem]

Yeah you can see it in the leaf tips curling up. I’d lower light a little, flush good with a low strength dose and work back up

 

[boomgagem]

I’d measure runoff instead of that in coco

 

[Grownsince95]

You have a temp/rh controller on the T4 right? What's it set at?

 

[Grownsince95]

If you are in Vermont on a well the temperature of your water might be a factor I know sometimes it can be really really cold

 

[curiousgrowth]

You have a temp/rh controller on the T4 right? What's it set at?

I have it setup to control humidity. It kicks on at 55% humidity. It’s turned off for temp control. Temps are at 74-78 with fan controlling humidity.

 

[curiousgrowth]

If you are in Vermont on a well the temperature of your water might be a factor I know sometimes it can be really really cold

Reservoir sits in room temp and I mix water at ~70-75 degrees by turning both hot and cold on at the same time because I hate waiting:)

 

[RealizedReal000]

If your using bottled nutes measure ph of run of but check ph of water going in. 4.5 is way low. I would water at the other end of the spectrum until medium ph is in correct range. If the medium is always moist and the ph is that off it will definitely show deficiencies.