Calcium Lockout?

[Kazman420]

Problem: Lightening of Leaves, Hammered Veins, Small White Spotting

Medium: 70% Canna Coco Professional Plus (Brick) / 30% Perlite in a 5 Gallon pot. (3.75 'real' Gallons) [I did not wash/buffer the coco].

Feed: General Hydroponics Flora Series - 6ml Micro / 9ml Bloom + 5ml TPS CalMag OAC [Per Gallon]. Manually Feeding 2x Day @ 5.8 pH and 350ppm [.5 Scale] (5-0-1 Micro, 0-5-4 Bloom, 0-0-0 CalMag). [Tips were burning at 375 so I recently backed down to 350ppm]

Water: Distilled. Fertigating to 20~30% runoff.

Strain/Age: Mephisto - Forum Stomper @ 57 Days

Light: 400w HPS @ 15 inches. 20/4. 50,000 Lux

Climate: ~55% RH / 77° Under Lights / 74° Leaf Temp

Additional Info: I'm wondering if I locked out Calcium by using PH Up (Potassium Carbonate). I have to add approximately 8~10 drops (per Half Gallon) every time I mix up my nutes. Appears to be starting from the top down. The leaf edges are also starting to curl a little, but that might be my fault for having the light a little too close for a few days. Previously I would make up a big batch of nutes and have to fight big PH swings every time I wanted to fertigate, now I just do whats needed at the time. Doing it this way has eliminated the need for the PH Down (Phosphoric Acid).

I also didn't realize the yellowing was this bad until just now when I moved her outside the grow room to take the pictures. The HPS really covers it up.

 

[Mañ'O'Green]

It looks over-fertilized to me. But it may be a balance problem on the nutrients. I find it hard to believe that you can overfeed at 350 PPM Hanna scale? Are you fertigating to 20% run-off by the end of the day? With distilled water you should be adding 50 PPM of Cal-mag to the water before mixing in your nutrients. Make sure you are mixing them according to the vendor instructions - the order matters.

Read this about balance:

Tutorial - A word on Nutrients

The proper use of “salt” based fertilizer to grow Auto Flowering Cannabis. Salts: Natural and man made any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation. Learning how to use salt based...

www.autoflower.org

 

[SargeantSpaz]

not an expert but trying to help a friend in need - you might have some lightburn as well?

400HPS @ 15 inches sounds too hot for me (I keep a 100W Spiderfarmer LED at that distance). the side curling could come from that.


I'm not negating in any way there's a nutrient problem, I'm just saying you could have some burn on top of that nutrient problem.
I second your hunch:

The leaf edges are also starting to curl a little, but that might be my fault for having the light a little too close for a few days.

maaaaybe you can even ignore the discoloration for now (could also be the lightburn, partly). what's making the leaves so shiny? they seem to have lost a bit their porosity.

 

[Kazman420]

It looks over-fertilized to me. But it may be a balance problem on the nutrients. I find it hard to believe that you can overfeed at 350 PPM Hanna scale? Are you fertigating to 20% run-off by the end of the day? With distilled water you should be adding 50 PPM of Cal-mag to the water before mixing in your nutrients. Make sure you are mixing them according to the vendor instructions - the order matters.

Read this about balance:

Tutorial - A word on Nutrients

The proper use of “salt” based fertilizer to grow Auto Flowering Cannabis. Salts: Natural and man made any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation. Learning how to use salt based...

www.autoflower.org

Thanks for the reply and the link @Mañ'O'Green. That was a great tutorial!

The highest I've ever gone with the nutes was 400ppm (.5 Scale) and the tips instantly burned. I backed down to 375ppm for a while but they were still continued to burn. Now I'm back to 350 and haven't noticed it getting any worse. I suppose it's possible my EC/TDS meter is out of whack. It's a HM Digital COM-80. It's two months old.

I make sure there is at least 20% runoff every time I fertigate. I see in the Nutrient Tutorial it says to make sure there 20% runoff "every day" you fertigate, not every time. So now I'm confused.

I'm adding the CalMag first, then Micro, then Bloom, making sure to mix thoroughly between. I never actually checked the ppm of just the CalMag (Doh!). I was simply adding 5ml. I'll make sure all future batches of nutes have 50ppm of CalMag per Gallon.

Any and all advice is appreciated!

 

[MIAutomatic]

I think the light was too close, that would explain the cupping.

I would add more calmag and that will actually allow your plants to uptake nutrients better. This is true in most growing mediums, but coco uses more calmag than soil or other hydroponic mediums. A good general rule is an EC of about .4 or around 200ppm calmag for coco.

Once you get your calmag dialed in a plant that size should be able to feed at 800-1100 ppm during heavy flowering without burning. That has been my experience anyway.

Read up on https://www.cocoforcannabis.com/ they have lots of great info on how calmag impacts a coco grow.

happy growing!

 

[Kazman420]

not an expert but trying to help a friend in need - you might have some lightburn as well?

400HPS @ 15 inches sounds too hot for me (I keep a 100W Spiderfarmer LED at that distance). the side curling could come from that.
View attachment 1384132

I'm not negating in any way there's a nutrient problem, I'm just saying you could have some burn on top of that nutrient problem.
I second your hunch:


maaaaybe you can even ignore the discoloration for now (could also be the lightburn, partly). what's making the leaves so shiny? they seem to have lost a bit their porosity.

Heyas @SargeantSpaz! Thank you for the image! I know I had the lights a little too close during this last week. I kept messing with the distance, going by various charts and the "back of the hand" method. I finally picked up a cheap LUX meter. Previously I was around 13" but I discovered they were being blasted with about 65,000 Lux. Now it's at 15" and they are getting about 50,000. I'm not opposed to raising them even more.

You're absolutely right about the leaves suddenly becoming so shiny! It wasn't like this a few days ago. The lower fan leaves have a "fabric" type feel, and the upper ones are dry and firm.

 

[Mañ'O'Green]

You can download Photone for free it measures light on your cell phone in PPFD or DLI. The back of your hand is the best for setting the distance from the HID lamp to the canopy. 200 PPM of calcium is too much. even in coco and 500 PPM of nutrients is all you need for autos.

Why don't you get some real tools to measure EC the HM Digital COM-80 is a PH pen as far as I can tell. What are you using for EC?

 

[DCLXVI]

Why don't you get some real tools to measure EC the HM Digital COM-80 is a PH pen as far as I can tell. What are you using for EC?

I have the same one. It measures EC and PPM. You can switch the scales on it from EC to 0.5 and 0.7 scales. It does temp also but not pH. It does look exactly like most pH pens. I did get calibration fluid for mine just to check but it's been quite accurate. Batteries might need a change if it's reading one number but results say otherwise. Cal fluid is cheap insurance too.

 

[Kazman420]

You can download Photone for free it measures light on your cell phone in PPFD or DLI. The back of your hand is the best for setting the distance from the HID lamp to the canopy. 200 PPM of calcium is too much. even in coco and 500 PPM of nutrients is all you need for autos.

Why don't you get some real tools to measure EC the HM Digital COM-80 is a PH pen as far as I can tell. What are you using for EC?

Thanks for the link! For some reason I thought the Photone app was for iPhone only, so it's nice to see they have a version for Android. Previously I was using the Migro LUX to PAR Hack. Looking forward to testing the app out.

I just measured the TDS of 5mg CalMag (which is what I have been using) and it came out to 68ppm (.5 Scale). I'll try lowering it to 50ppm.

 

[Kazman420]

I have the same one. It measures EC and PPM. You can switch the scales on it from EC to 0.5 and 0.7 scales. It does temp also but not pH. It does look exactly like most pH pens. I did get calibration fluid for mine just to check but it's been quite accurate. Batteries might need a change if it's reading one number but results say otherwise. Cal fluid is cheap insurance too.

I ordered the calibration fluid from Amazon like 2 hours ago. It'll be here Thursday. I had read the COM-80 was fairly accurate out of the box and typically didn't need to be calibrated, but I'm making myself nuts over this nutrient problem so I'm covering all angles.