Switch from promix to coco. Issues need advice

Hi All,
I have recently ran a little low on cash and decided to use some leftover GH cocotek blocks I've had lying around. I usually grow in a promix, worm casting, perlite, various amendments and produce a wonderful product but I decided to sub coco for my promix this go around thinking it would be worth a shot.
I double hand washed the coco blocks in a large container to rid it of any salts or what have you. Once washed I could squeeze the coco and almost clear water would run through. I then charged it with a light calcium dose and mixed in the rest of my amendments. Rough ratio is about 40% coco 30% perlite 30% worm castings as this is how I usually mix my promix.
First week or so plants were very healthy and vigorous. I watered them as I would soil letting the coco dry out about 2 inch from top and water again. Feeding every other water. Watering every 2-3 days. About week 3 veg plants began exhibiting what I diagnosed as magnesium def. Hit them with Epsom salts and a litle extra calcium. No change. I use nectar for the gods and follow quite close to their feeding schedule. Feed every other water at this point. Now at this time I was not checking pH. I never had to using promix I always added some lime and never had any pH issues.
Started doing some research about growing in coco and basically read if I treat it like soil it will not survive. So I stopped treating it like soil and began watering once a day with light nutes. I have noticed a slight change in new growth but still exhibit major mag def as well as slight leaf tip burn and leaf curl. I now keep track of my pH going in as well as run off and I am between 5.8 6.2 always. I feel like I can't get this coco right and am getting frustrated. Any advice would be appreciated. Never been on any forums either in 10+ years of growing so I am really stumped on this one. Should I flush? Stop watering so much?
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Well I should also say this is a kksc and always has been fussy for me. I am doing c99 as well and it doesn't exhibit any of these characteristics. I am trying to get some pics

I can see why you'd think it was mag def but truth is, mag def looks little different. I think you have two problems.
1. your pH is too low. playing the pH game really shouldn't be necessary, even though people say it is.
2. your not ferting properly. I'd try a more general fert that has more to it, like dynagrow 7-9-5, or something similar. If you read the labels, you should be able to see many different fert elements like boron, mag, Sulphur, calcium, zinc, etc. It's hard to know what deficiency you have right now, but it's clear that since coco doesn't have any fert to it (and promix does) that you're missing at least one vital element. So a well-rounded fert will probably make a big difference. Just don't over do it on the fert. Read the back and follow the instructions, but don't feed to often or you'll have a different kind of problem.

Thanks for your input. I could agree with you about their being some type of def. So I have some cytoplus brewing with some sugars and will try this for a couple days. Added some 0-10-0 as well.

Not really the right thing to, except the cytoplus is probably a good idea, however it's not the fertilizer that your plants need. cytoplus is a combination of soluble seaweed extract, HumiSolve and seven micronutrients required for plant growth. It's good to use this stuff, especially in coco, but you need to use a NPK kind of fert. Just giving 10 of phosphorus isn't really the right move and you don't want excess of anything to build up in the coco. I'd get a well-rounded fert and use that instead. maybe try to wash that phosphorus out before you fert again. your plant with need nitrogen and potassium, which neither of those you gave seem to have. A well-rounded fert like dynagrow, used properly and carefully and not overdoing it, would be your best bet.

polishpollack said:

I can see why you'd think it was mag def but truth is, mag def looks little different. I think you have two problems.
1. your pH is too low. playing the pH game really shouldn't be necessary, even though people say it is.
2. your not ferting properly. I'd try a more general fert that has more to it, like dynagrow 7-9-5, or something similar. If you read the labels, you should be able to see many different fert elements like boron, mag, Sulphur, calcium, zinc, etc. It's hard to know what deficiency you have right now, but it's clear that since coco doesn't have any fert to it (and promix does) that you're missing at least one vital element. So a well-rounded fert will probably make a big difference. Just don't over do it on the fert. Read the back and follow the instructions, but don't feed to often or you'll have a different kind of problem.

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Pro mix has no fertilizer to it. It's peat moss with vermiculite and perlite. With a light D lime mixed in. Some might have mycorrhizae but that's no fertilizer.

that's funny, I've contact the company that makes promix and the rep said there is a fertilizer charge added to the potting soil.

polishpollack said:

that's funny, I've contact the company that makes promix and the rep said there is a fertilizer charge added to the potting soil.

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The reason people use it is because it's a sterile clean slate that is PH neutral. There are some forms with fertilizer in there but it's not pro mix. I think fox farm is one that does. But a true pro mix is just peat and V & P.

I mix plenty of nitrogen supplements into the coco including worm castings, alfalfa meal, feathermeal, blood meal. Cytoplus is 0-0-7.5. Which is plenty of potassium and if I add small amounts of 0-10-0. (Herculean harvest) the plants should have what they need. If my feeding doesn't work I will try another fert I am just trying to avoid spending cash on new ferts because I have gallons upon gallons of nftg. Thanks again your advice is much appreciated

GOLDBERG71 said:

The reason people use it is because it's a sterile clean slate that is PH neutral. There are some forms with fertilizer in there but it's not pro mix. I think fox farm is one that does. But a true pro mix is just peat and V & P.

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That's right. I like to buy the cheapest, big box store, version for a consistent $14 2cu ft. I add additional perlite and I add myco to the rootball and pot bottom at transplant. I think it great! Yeah, no ferts.

Yea I've always had good luck with promix or bm series. I really am kicking myself in the arse for subbing coco for it. I only have a few plants in their final home the rest are sitting in gallon containers so depending if I cant fix the problem with what I have I might just have to dig up the ol change jar and go buy some promix. They are already starting to look better since I started tweaking the feedings. Ill keep you guys informed of what works for me.

Ok here is some advice from a coco fanatic. Use the KISS method. I use GH cocotek bricks and there is no need to rinse. Just expand, add perlite and vermiculite if you want (verm is optional). Coco works amazing with little to no amendments. Coco and perlite and maybe a little vermiculite is all you need. PH is KEY with coco. 5.7-5.9. Nothing less or more. You can feed everytime you water. You need to use a cal mag supplement. You can add oyster shells to the coco or top dress, and use epsom salt when you water. If you are going organic this is probably the way to go. Don't worry about run off ph. It will never be what you want it to be. It will always be high. Only be concerned with the ph of the water/solution going in. Coco is Hydro and if you treat it as such you will be fine.

Since it is hydro you want to to be able to control completely what you are giving it. Hence the reason you can feed everytime. Adding amendments to it such as castings or calcium can affect how you feed it. Coco is an amazing medium that is so forgiving if you treat it right.

Here are my Keys to coco success:

PH at 5.7-5.9 ( I always shoot for 5.8
4ml CaliMagic per Gallon everytime you feed/water
Use nothing but coco and sterile amendments. Perlite, vermiculite, hydroton. (You can add mycorrhizae)
Make sure to calibrate PH meter regularly since you have a small window for PH.
Use a PPM/TDS meter
RO water if you have shitty tap water. Mine is amazingly pure at 75TDS
If not using RO then let water sit 24hrs to evap chlorine (especially if using mycorrhizae)
Let coco dry out a little between waterings but not too much.


That's it. It's that simple!

A lot of people say to water to 10% run off but I rarely do and never have problems. If you are pushing them hard I can see the need because of salts building up.
I definitely flush before harvest though until my runoff is close to my tap water TDS. Then I reuse the shit. Over and over and over... Hygrozyme or pond protector are a good idea if you plan to reuse.

I recently changed from hand watering to an automated system. I was going to switch to rockwool and hydroton, but am going to use coco chips. It will give me the ability to feed more frequently via ebb and flo or drip feed and I figure since coco treats me so well why stray away. Coco is king!!

Nice info! Thank you. I am still curious when to water/frequency. Amount of feed? Ppm? What type of nutes do you use? I don't have an ec meter only tds. I am in 5 gal and have been watering about 32oz per pot everyday. I have leaf cup/leaf curl which makes me contemplate if they are too wet or too dry.

I also setup a quick autowater for days I can't be around but havent really had to use it. Still hàndwatering cuz i don't know of a correct frequency. I have low ppm tap water as well. Only 60ppm but it is because I have a 20" inline filter as well as a culligan softener. I just watered this morning with calmag pH at 6.4, ppm at 350, water temp 65F.

I will take your advice researching and wait for the coco to dry out a little more. Maybe every other day or two would be more optimal in a larger pot. I will also keep my pH slightly lower.

on these issues might help some guys using nectar for the gods in coco. Or noobs to coco in general.

Every other day I feed high ppm. 300-400.
Gaia mania 2 tsp gallon
Medusas magic 1 tsp gallon
Herculean harvest 2 tsp gallon
PH up to 5.8-6.2

Low ppm every other day 100-200 ppm
Demeter's destiny 5 ml gallon
Athena's aminas 15 ml gallon
Carbon 5 ml gallon
H202 3 ml gallon
PH 5.8-6.2

Once a week along with low ppm nutes
Slf100 5 ml gallon
Zeus juice 5 ml gallon

Day after I always add beneficial bacteria

Once every two weeks (flush)
Herculean Harvest 15 ml gallon

Day after add beneficial bacteria

This is what the strawberry coughs are looking like now.
https://www.flickr.com/gp/135246391@N06/627860Update
Compared to before
https://www.flickr.com/gp/135246391@N06/K421P6