Autopot deficiency Help

[Blunoser]

Hi all, hope someone can point me in the right direction on this issue. I am on my second grow in an autopot system and both times the plants have developed deficiencies around wk 4 veg and into flower. Leaves yellow then black appears and they just turn crispy and die. My pariticluars are, Coco perlite 70/30mix , 3cm pea gravel and air domes. Gh flora nutes , Ph 5.6-6.2 ( it seems to drop in the res so i set it high and let it drift down) Ec started 0.6 up to 1.4. Lights are 2 cmh 315w in a 1.6m x 1.3m x 2.2m room. 10cm exhaust and 10cm intake fan. 2 fans on 30cm circulating and 1 20cm stationary. Temps for the grow 18c-28c , Humidity is 50-66%. I have tried adjusting different ph different ec (low higher) and some epsom salts all to no avail. If any of the community out there has any ideas i would sure appreciate the help as i am in week 5 flower and i can't see these plants making it to the end. attached a couple of pics to ponder
thanks in advance

 

[Mañ'O'Green]

What is the source of your pea gravel? It may be contributing minerals to the nutrients causing lock-outs. You should use high quality PH stable Hydroton Clay Pebbles which are inert. Do not buy the cheap ones or you'll be in the same boat.

We need to see pictures in Day Light 5000K color or flash. Turn off the grow lights.

 

[Blunoser]

Thanks for the response Man. I washed the pea gravel several times because of just that reasonand even soaked it in ph'd calmag in a bucket. Could it be to much light for them. I have the lights 70cm above the canopy? As for the pics i still learning the "proper" technique. So i go in the room at lights out and use the flash to take pics, correct? Not sure what is you mean with 5000k.
Appreciate the response. as they say live and learn

 

[St. Tom]

Thanks for the response Man. I washed the pea gravel several times because of just that reasonand even soaked it in ph'd calmag in a bucket. Could it be to much light for them. I have the lights 70cm above the canopy? As for the pics i still learning the "proper" technique. So i go in the room at lights out and use the flash to take pics, correct? Not sure what is you mean with 5000k.
Appreciate the response. as they say live and learn

take some pics in natural light i grow in autopots and if i see deficiencies it normally tends to be cal-mag that i need as these led lights seem to need more also when you first started your grow when you were top feeding was you feeding to run off all the time as i sometimes have got lockouts or build up that way and i give them a mini flush and see what ec your coco is holding by top feeding and catching your runoff over a bucket if its sky high or tons higher that what your putting in i give them a flush before putting them back on your res .and one more thing that's a bit low 18c for lights out for me anyway also are you in the UK

 

[Blunoser]

greetings St Tom Im in Canada, beautiful place called the Annapolis Valley ( Highest tides in the world). I grow in a basement room thats where the temps arrive from. I have a heater in there and it maintains 18c. I will turn it up if it is required. when i first started "top" watering i made sure i had plenty of run off ( trays would almost fill and i would suck it up with shop vac 2x each watering) As for calmag i've been adding between .3 and .35ec every feed. Is this too light i wonder?
I flushed all 4 yesterday with 10L each and at the end the ec dropped 0.2 on each plant. Started at 1.2 to 1.4 and ended at 1.0 to 1.2ec. Spent most of my day off mixing and ph ing trying to "start a new". My res ec was 1.3 and after the flush i have lowered it to 0.9. I have grown beautiful plants in coco before but that was hand watering. That was a major time consuming pita and the Mrs thought i was losing my mind as i was dragging roughly 600L of water to the grow down the basement and the waste back up. I was hoping autopots might help alleviate some of this but this is my second attempt and i am experiencing the same issue as before only worse. I would hate to give up on the Autopots (not only for the $$$) as It is definelty a great system if i can only figure out the darn things. Sometimes i think i need to be a chemist to grow my gd left hands smokes
As you can tell by the log winded post i am at my wits end.

 

[Olderfart]

greetings St Tom Im in Canada, beautiful place called the Annapolis Valley ( Highest tides in the world). I grow in a basement room thats where the temps arrive from. I have a heater in there and it maintains 18c. I will turn it up if it is required. when i first started "top" watering i made sure i had plenty of run off ( trays would almost fill and i would suck it up with shop vac 2x each watering) As for calmag i've been adding between .3 and .35ec every feed. Is this too light i wonder?
I flushed all 4 yesterday with 10L each and at the end the ec dropped 0.2 on each plant. Started at 1.2 to 1.4 and ended at 1.0 to 1.2ec. Spent most of my day off mixing and ph ing trying to "start a new". My res ec was 1.3 and after the flush i have lowered it to 0.9. I have grown beautiful plants in coco before but that was hand watering. That was a major time consuming pita and the Mrs thought i was losing my mind as i was dragging roughly 600L of water to the grow down the basement and the waste back up. I was hoping autopots might help alleviate some of this but this is my second attempt and i am experiencing the same issue as before only worse. I would hate to give up on the Autopots (not only for the $$$) as It is definelty a great system if i can only figure out the darn things. Sometimes i think i need to be a chemist to grow my gd left hands smokes
As you can tell by the log winded post i am at my wits end.

Hi, and sorry to hear about your problem. Almost everything you have done sounds fine to me, there is nothing wrong with the coco/perlite mix, provided it was buffered, your EC's are fine, and I guarantee that there is nothing wrong with the Autopot system itself. My first grow with autopots was excellent with a coco mix similar to yours, although I used ~60/40 coco perlite throughout the pots, with no airdome.

I second @Mañ'O'Green's suspicion about the gravel. Importantly, washing/buffering it may not cure the problem. If it is the wrong type of rock, the slightly acidic nute mix could result in it releasing stuff that could cause lockout. Did you use this stuff in your hand watered grows? Did you use it in both autopot grows? If you used it for the first time in both autopot attempts, it may be your problem. Some types of rocks out there bugger with both your nute mix and the pH of your medium. And contrary to some of the advice out there, coarse material like gravel or hydroton at the bottom of autopots is NOT required, and may be harmful. Quite aside from nute or pH effects, the abrupt change in particle size at the boundary of the rocks/hydroton and grow medium interferes with wicking of nutes from the flood zone up into the rest of the pot. As my grow and likely many others demonstrate, a well drained medium is all that is required, all the way to the bottom of the pot. Air domes seem to add little when peeps compare with and without, and they do add complexity and dependence on uninterrupted electricity.

None of which helps you fix the current problem. If no other explanation for the problem emerges with more expert advice, and I were in your boots, I would just call quits on autopot subirrigation for this grow, and top water to significant runoff to finish off. By doing that, you may reduce the influence of the problematic gravel in the bottom of the pot. If all the nutes are not travelling up through the gravel or sitting in it during the flood cycle, whatever mischief it might be causing would at least be reduced if not eliminated. Just a guess on my part, but that is what I would do. And next time, just stick to coco/perlite all the way down, and no air dome. In this case, simple really is good, IMHO. Don't give up on the autopots, they kick serious butt, especially with fabric pots.

Good luck with it, I hope you manage to save the grow.

 

[Mañ'O'Green]

18°C is too cold for most cannabis strains to thrive. 26°C Day and 20°C night is ideal. I remember reading about some cold weather strains but don't remember much because I live in the desert where the cactus are the happiest plants.

@Olderfart That is a great idea, top fertigating with 20% run-off-to-waste would indeed minimise any input from the gravel. We do not know if that is the issue yet if it is a rapid improvement should be observed.

 

[Blunoser]

Hi, and sorry to hear about your problem. Almost everything you have done sounds fine to me, there is nothing wrong with the coco/perlite mix, provided it was buffered, your EC's are fine, and I guarantee that there is nothing wrong with the Autopot system itself. My first grow with autopots was excellent with a coco mix similar to yours, although I used ~60/40 coco perlite throughout the pots, with no airdome.

I second @Mañ'O'Green's suspicion about the gravel. Importantly, washing/buffering it may not cure the problem. If it is the wrong type of rock, the slightly acidic nute mix could result in it releasing stuff that could cause lockout. Did you use this stuff in your hand watered grows? Did you use it in both autopot grows? If you used it for the first time in both autopot attempts, it may be your problem. Some types of rocks out there bugger with both your nute mix and the pH of your medium. And contrary to some of the advice out there, coarse material like gravel or hydroton at the bottom of autopots is NOT required, and may be harmful. Quite aside from nute or pH effects, the abrupt change in particle size at the boundary of the rocks/hydroton and grow medium interferes with wicking of nutes from the flood zone up into the rest of the pot. As my grow and likely many others demonstrate, a well drained medium is all that is required, all the way to the bottom of the pot. Air domes seem to add little when peeps compare with and without, and they do add complexity and dependence on uninterrupted electricity.

None of which helps you fix the current problem. If no other explanation for the problem emerges with more expert advice, and I were in your boots, I would just call quits on autopot subirrigation for this grow, and top water to significant runoff to finish off. By doing that, you may reduce the influence of the problematic gravel in the bottom of the pot. If all the nutes are not travelling up through the gravel or sitting in it during the flood cycle, whatever mischief it might be causing would at least be reduced if not eliminated. Just a guess on my part, but that is what I would do. And next time, just stick to coco/perlite all the way down, and no air dome. In this case, simple really is good, IMHO. Don't give up on the autopots, they kick serious butt, especially with fabric pots.

Good luck with it, I hope you manage to save the grow.

Thanks guys for all the advice and i am going to take it. I did buffer coco 2ml/L for 24hrs. As for 18c temps i have not had those temps at lights out for 2 months (we have been in a "Canadian heat wave 30-35c temps and we ain't use to that) usally lights out 21-22c. I dug down a little in the pots and they are solid roots not sure if this may be an issue. I "shot" the leaf temps and they run 25-26c, room is 27-28c lights on. I attached a spreadsheet with my enviroment data for perusing. Maybe there's something you guys can see in there. I guess i still grasping at straws. It is what it is and i am going to have to deal with it.
Sh_t back to hand watering. Oh well i got maybe 3 or 4 weeks left ( if they make it).
I don't want to give up on autopots. I do a fall grow so come Oct I will try again ( don't usally do summer grow but free clones and here we are). I am going to try coco perlite 60/40 and no "aggregate in the bottom. I am going to try a lower ec maybe. I may switch my light back to my 600w hps as I have had exellent grows with that in the past. Any thoughts on this
Thanks again for the help St Tom and Man O Green i will take your advice and finish with a "top" watering SH-t
ps didn't mean to quote but not sure how to take it out yet. I'll learn

 

[Blunoser]

Didn't you can't send xls. My bad, Still learning

 

[Blunoser]

The hand watering hasn't improved the leaf problem but it's not getting worse. It looks like the buds are going to make it they are dense and swelling. I'm gonna post some pics on the weekend. Lights are on when i get off work and long after i go to bed. I am heginning to wonder if i didn't burn the plants with light. When i Look inside the canopy it's green and healthy but outer leaves are yellow and curled some are even brown and crispy. I had 2 315w cmh lights 40cm above the canopy, could this be too close?