Coco - Unknown Issue

[Student Of Life]

3 gallon containers

Canna Coco bricks expanded with low-strength Canna AB

Canna AB nutes, have also tried 6/9 with epsoms. Usually around 1.2-1.4 EC either way.

Hand watered twice a day to runoff, pH 5.7-6.0

Temps 80, rH 65

600w MH

Only additives have been drip clean, SM90, and protekt.

Ok so the issue is that I'm getting a very persistent decaying of the lower/middle leaves. Always starts at the lowest part of the girls and works its way up. Looks a bit like K deficiency or salt buildup. I don't see how it could be K, who gets K deficiency in veg with Canna AB or GH 6/9? It's not salt buildup, as I water to runoff and test runoff ppm once a week. This is driving me nuts. It has plagued my first grow straight through to flower, and drastically lowered my yields. It is still persistent in round 2 veg, despite me trying a bunch of stuff to figure it out.

I've tried lowering ppms to ~250 and supplementing calmag. I've tried higher ppms and cutting calmag out. I've tried switching to GH 6/9 with 1gr/gallon epsoms. I've tried watering to no runoff, watering to tons of runoff. I'm not going to give up on this issue, I just need some help from the more experienced coco growers out there. What does this look like to you?

 

[ganjalfthegreen]

You checked for root aphids?

 

[Student Of Life]

I did a quick google search and it says that I should be able to see them with the naked eye. I don't see any bugs, eggs, or anything out of the ordinary on the coco's surface or the drain holes in the pots where the roots are bursting out. I also use SM90 religiously (if that helps). I'll take a better look tomm when I go down there for their morning watering. Should I pull a plant out of her pot altogether and get a real good look?

 

[HqFarms]

What size pots, how long of a veg? I personally like a higher ph of 6.0- 6.4. To me it looks like you have ph fluctuations because the coco is drying out

 

[HqFarms]

To answer your question about a k deficiency, excessive nitrogen, calcium, or magnesium can lock out k

 

[Granger2]

I don't see how watering 3 gal pots of coco twice a day to runoff would let the plants dry out.

Try the potato test to check for RA's. Good luck. -granger

 

[Student Of Life]

Ok good news all around. First of all, as you can see by attached photos, it is not root aphids. That's good. Problem is I've let salt buildup get out of control by only testing one or two girls up closest to the res (like a lazy ass). Tested some more of them this morning and runoff was reading 4.0 EC. Sheesh. So it's time for a good old flush. Is the first attached picture an example of salt building up on the coco's surface? I've never had that happen before switching to GH.

 

[dansbuds]

i've seen numerous people posting this problem with coco lately . 90% of the time its either not enough runoff or leaving the runoff so the plants can suck it up . if you don't have a drainage system in place or can't get to the runoff right away to suck it up , use drip clean or Z7 to eliminate the build up in the coco would be my suggestion .

 

[Student Of Life]

dans, it might be too high of EC. I'll explain the setup and you tell me what you think. I water them twice a day, about 10-12 hours apart. Morning watering is just almost to the point of runoff, night watering is plenty of runoff (wouldn't know the % but it's plenty, almost streaming out of the drain holes). The girls are sitting in flood trays and the excess water gets vacuumed out after a couple minutes of letting them drain. The girls aren't drying out between waterings.

I feed them around 1.3-1.4 EC, and three of the 18 are showing nute burns on the tips of leaves. Do you think that a constant supply of slightly overpowered nutes has contributed to the salt buildup?

 

[HqFarms]

Get a moisture meter, they are super cheap, and check what the moisture is before they get fed. I bet it's not as moist as you think it is. Coco can look wet on the top but really not be wet at all.

To your question about constant supply of over powered contributing to nute burn, the short answer is yes.

 

[dansbuds]

dans, it might be too high of EC. I'll explain the setup and you tell me what you think. I water them twice a day, about 10-12 hours apart. Morning watering is just almost to the point of runoff, night watering is plenty of runoff (wouldn't know the % but it's plenty, almost streaming out of the drain holes). The girls are sitting in flood trays and the excess water gets vacuumed out after a couple minutes of letting them drain. The girls aren't drying out between waterings.

I feed them around 1.3-1.4 EC, and three of the 18 are showing nute burns on the tips of leaves. Do you think that a constant supply of slightly overpowered nutes has contributed to the salt buildup?

yup .... 1.4 is kind of high unless your really blasting them with light or running CO2 where the plants will eat more .
as your finding out coco holds onto what the plants don't use/need & it builds up quick .
either flush & lower your dose back to 1.2 or use the drip clean or Z7 enzymes to get rid of it at each feeding to runoff . but i'm a firm believer in that you should feed low & bring the EC up if the plants need it , then to feed to much & have to flush it out .

 

[Student Of Life]

Thanks Hqfarms for your help, I'll try to be more on top of keeping the coco wet. Dans, the plants will all be flushed down to .8EC by the end of the day, and I'll stick with that strength for the next few days to see if they need more or if the buildup continues. I was using drip clean in the past, and stopped when it ran out to see if I could cut costs. Picked up the bottle again this morning at the hydro store lol. I want to nail the EC issue though, so as not to rely on drip clean and instead get a better understanding of what the girls need. Thanks for your help brother.

 

[dansbuds]

Thanks Hqfarms for your help, I'll try to be more on top of keeping the coco wet. Dans, the plants will all be flushed down to .8EC by the end of the day, and I'll stick with that strength for the next few days to see if they need more or if the buildup continues. I was using drip clean in the past, and stopped when it ran out to see if I could cut costs. Picked up the bottle again this morning at the hydro store lol. I want to nail the EC issue though, so as not to rely on drip clean and instead get a better understanding of what the girls need. Thanks for your help brother.

then stick to no more than 1.0 for veg & no more than 1.2 for flower as a starting point . the plants will tell you if they want more .

 

[Student Of Life]

then stick to no more than 1.0 for veg & no more than 1.2 for flower as a starting point . the plants will tell you if they want more .

Well, this may be hard to believe, but the salt is already starting to build back up just four days after flushing the coco down to .8 EC. Runoff today reads 1.4 EC, despite the nutes going in reading 1.0-1.1. Is it possible that a 'bad batch' of coco will result in quicker/more severe salt buildup?

I've been watering twice daily still, and the coco never dries out. Second watering results in good runoff, and have added drip clean to the recipe. After the flush, EC was brought down to 1.0 from 1.4. To further complicate things, a calcium def started showing up the day after the flush, as if I wiped out the coco's stored calcium. Yikes, I've got to get this sorted out, flower is approaching rapidly.

 

[maimunji]

Its normal if you make slurry test you will be surprised how low is your ppm no more than 400-500 im sure. Just do it.

 

[dansbuds]

what did you flush them with ? hopefully it was a low dose nutes & not plain water . any plain water feeds during the cycle will throw the cations out of balance & the coco would have to be recharged & you'd see some defs for a few days . the .8 feeds at a PH of 5.8 should clear it up after a few feedings .

 

[soundman]

I would also go to watering to runoff on all waterings. Light feeders leave salts behind while using the water. Watering to runoff will help that,

 

[Student Of Life]

Its normal if you make slurry test you will be surprised how low is your ppm no more than 400-500 im sure. Just do it.

What's the water to coco ratio for a slurry test?

what did you flush them with ? hopefully it was a low dose nutes & not plain water . any plain water feeds during the cycle will throw the cations out of balance & the coco would have to be recharged & you'd see some defs for a few days . the .8 feeds at a PH of 5.8 should clear it up after a few feedings .

I flushed with .8 EC nutes until the runoff was .8, down from 4.0. pH was 5.8-5.9. The calcium problem was clearing up this morning when I went in for the morning watering, but the salts are definitely accumulating again. Current runoff at 1.5 EC atm, when the nutes going in are only 1.0-1.1.

I would also go to watering to runoff on all waterings. Light feeders leave salts behind while using the water. Watering to runoff will help that,

I hear you, but that only seems like a temporary fix. I've seen plenty of good growers (DJM and medicropper off the top of my head) who don't water to runoff in coco and don't get salt buildup issues. It shouldn't be necessary to water to runoff multiple times a day. I need to figure out how to prevent the buildup from happening in the first place.

 

[soundman]

What's the water to coco ratio for a slurry test?



I flushed with .8 EC nutes until the runoff was .8, down from 4.0. pH was 5.8-5.9. The calcium problem was clearing up this morning when I went in for the morning watering, but the salts are definitely accumulating again. Current runoff at 1.5 EC atm, when the nutes going in are only 1.0-1.1.



I hear you, but that only seems like a temporary fix. I've seen plenty of good growers (DJM and medicropper off the top of my head) who don't water to runoff in coco and don't get salt buildup issues. It shouldn't be necessary to water to runoff multiple times a day. I need to figure out how to prevent the buildup from happening in the first place.

Not a temp fix. It works. Sure some grow without runoff. They are the minority and probably grow mono crops of strains that are well dialed in. Maybe use drip clean etc too?

I grow mixed strain runs. Watering to runoff keeps me from mixing different strength nutes for each strain. I get no deficiencies.

I also believe in watering to runoff to ensure a complete gas exchange in the ccoco. I want oxygen rich solution reaching the bottom of my containers.

Lots of ways to skin a cat. Good luck finding your solution.