Coco/perlite problems

[The Grass Baas]

Hey watsup guys.

So I've just recently gone about experimenting between living soils and coco/perlite mixes with GHE tripart nutes. What I have noticed is that the growth is some much quicker with the GHE coco/perlite. I originally tried 2 different strains, both treated the same but for some reason the one is struggling with some sort of issue. 

Break down:

• 4x 20lt pots with coco 80% and perlite 20%.
• Coco was buffered for 24 hours everytime new substrate was made (used granual calmag supps, enough to bump EC from about 0.2 to 0.4 max. Usually not higher than 0.3EC), water was also PH balanced to 5.8 with the buffering.
• GHE tripart.
• Watering always between 5.8 and 6 PH and the EC is within the range for vegetative growth according to the final vegetative feeding amounts
• Plants went from clone to 12cm pots to 23cm pots to 20L grow bags, everytime going through the same buffering etc.

To be honest I never know how to measure my RO water. I would feed the plants between 2lt and 4lt of late, depending on how much RO I get. I usually aim for 20% to 30% RO.

So the big question is what is making these specific plants do this and not the other strains? I have been noticing yellowing coming from the tops of the leaves. I am not too bad with understanding mobile and immobile nutrients etc. Maybe I am shit. I don't know. From my countless hours of trying to figure it out, the conclusion I have come to is that the plants are struggling from a sulphur deficiency. There is zero yellowing coming from lower leaves. At the tops they have been a little yellow throughout their lives and it's gotten worse now a week before flowering. The yellowing seemed very mild and would see blotches on leaves here and there becoming yellow and yesterday I saw for the first time both fan leaves growing from a node being way too yellow for my liking. 

• What I have done so far is do a very light foliar spray of Epsom salts (1x teaspoon with 2Lt water) and the next day when I watered, I decided to give them each 2lt water with 1x teaspoon Epsom salts in the growing medium. Ph was balanced to 6.0 and out of interest I measured the EC and got close to 1.3 EC. Reason I haven't been adding Epsom Salts to the GHE is because then my EC would be through the roof. 

I can't seem to think of any other info needed to help diagnose this issue. Please let me know if there are more questions that would help with diagnosing this issues. Also if you are super pro and know how to measure runoff and read it, it would be greatly appreciated for a quick explanation on how to measure and read it.

[The Grass Baas]

Sorry. "RO" water is "Run Off" water and not "Reverse Osmosi" water. Sorry if there is any confusion

[PsyCLown]

I am not great at diagnosing deficiencies as I struggle with colour a bit.

 

When I use to buffer my coco, I would get the calmag solution a lot higher than 0.3 EC I would aim for around 1.2 EC to 1.6 EC to let the coco sit in to ensure proper cation exchange. Perhaps it was a bit excessive. I recall someone mentioning they used an EC of around 0.8 when buffering their coco and never had issues.

To me, 0.3 EC to buffer seems a bit low. So it is possible that is part of the issue. As for why it is affecting only one of the strains is a bit weird but could be due to the demand for certain nutes which the one strain has vs the other strain. You could try add a little more micro to the mix as that contains some the calcium and some magnesium too. You could add a bit extra calmag as well (I think it was 1g or 3g per 10L for maintenance) to the feed if you feel the coco may not be buffered properly.

 

Now a days I just purchase already mixed and buffered coco, much easier for me.

 

Are you using the soft or hard version of the GHE nutes and is it normal tap water? Filtered water? Borehole?

[The Grass Baas]

Thanks for the response dude. Appreciate it.

So currently I am using the Hard water Micro as I live in central PTA. Well that's the recommendation as apparently we have harder water here (when I test my tap it says 0.2EC and the PH is usually like 6.8). This depends though because the PH does fluctuate a little. 

I definitely think that the one strain seems to be handling it alot better than the other purely because of genetics. I moved away from buying bags of ready made soils as it wasn't consistent and I would get a hot soil now and then. Also I wanted to save money. I see alot of the guys sell ready made coco perlite mixes which then cost the exact same as the living soils. So for me I feel like it's a bit of daylight robbery. Either way. Just trying to become better with the coco and understanding it.

Great tip to use a little more micro and possibly my buffering might be too low. I just followed what they said on the pack. Here is an attached screenshot. Seems as though the buffering would be the same as the maintenance. 

I have attached a screenshot from GThydro and I am pretty sure the Solid calmag from Hydroponic.co.za is the same

[Batista]

Unwashed and unbuffered coco messed my entire grow this year, along with using too much perlite.

I would flush with tap water then buffer with a higher ec as mentioned. I also continued to feed calmag at every watering and this corrected my yellowing after about 3 weeks, watering once every 6,7 days which is not ideal for coco.

I should have just bought rinsed and buffered coco like the previous year lol

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[Leeroy420]

Hey guys what do you guys think if he ups his ph to about 6.3?

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[PsyCLown]

@The Grass Baas I am using the BioLeaf coco, it's cheaper than the imported brands.

Around R199 for a 60L bag - cheaper than the price of most soil people use for cannabis.

 

Might be a good idea to feed with extra CalMag for now and up the Micro a little and wait it out. Not worth pulling plants out of coco and trying to buffer again. It will correct itself, may just take a bit of time. 3g/ 10L is what is recommended for deficiency.

 

@Leeroy420 Never tried to adjust the PH to help. It could be worth a try.

[The Grass Baas]

Thanks oaks. 

I think I will keep it as is with the scheduled feedings but add a little more Calmag. I think I still have a abit of EC to play with. I will increase the Calmag for now and see what it does.

My biggest problem is I have to finish this grow before end October as I will be moving. Don't want to be moving with flowers in their peak. Therefore I'm forced to flip next week wednesday the latest. 

Thanks for all the help. 

 

[PsyCLown]

1 hour ago, The Grass Baas said:

Thanks oaks. 

I think I will keep it as is with the scheduled feedings but add a little more Calmag. I think I still have a abit of EC to play with. I will increase the Calmag for now and see what it does.

My biggest problem is I have to finish this grow before end October as I will be moving. Don't want to be moving with flowers in their peak. Therefore I'm forced to flip next week wednesday the latest. 

Thanks for all the help. 

 

I wouldn't worry about the EC much, the extra calmag won't increase the EC all that much and flower nutes on GHE are not that high in terms of EC when following the chart. You can safely push the EC To 1.6 typically without issues and that would give you around 0.3 to 0.4 EC of CalMag which can be added. I doubt 3g/ 10L will be more than 0.4 EC.

 

You are on a timeline for sure, size wise your plants are looking good though and a flip next week should be ok. Just going to have to deal with the issues going into flower, you have the 3 week stretch to help as well though and nutes will be pushed up during this stage anyways.

[The Grass Baas]

I just realized that I have been reading the measurements completely wrong all this time. I for some reason thought the buffering was per 10 litre and not 1 litre. 

So I am currently on day 11 of flowering. Still a slight deficiency (not major) but plants still growing fast. 

Would I be able to give them a flush with clean water, then buffer with the correct calmag for a day (1g/litre), then continue them on their feeding schedule into flowering?

[PsyCLown]

16 minutes ago, The Grass Baas said:

I just realized that I have been reading the measurements completely wrong all this time. I for some reason thought the buffering was per 10 litre and not 1 litre. 

So I am currently on day 11 of flowering. Still a slight deficiency (not major) but plants still growing fast. 

Would I be able to give them a flush with clean water, then buffer with the correct calmag for a day (1g/litre), then continue them on their feeding schedule into flowering?

I wouldn't flush with plain water, you could flush with the correct calmag dose and then give a heavy feed of normal nutes a day or two later and get some run off.

[Nope]

1 hour ago, PsyCLown said:

I wouldn't flush with plain water, you could flush with the correct calmag dose and then give a heavy feed of normal nutes a day or two later and get some run off.

[Marzcanna]

I would recommend to wash & buffer your coco regardless if you purchased a "washed and buffered" coco. 

As @PsyCLownmentioned wouldn't flush with plain water, a very low nute dosage probably a quarter of the recommended dosage will get you around 200 - 250 ppm if using RO water, that will do the trick. 

Edited August 20, 2021 by Marzcanna