Runoff EC always creeping up

growlo_b · Oct 5, 2020

Hi,

I'm on my second grow in coco and I've been battling salt buildup issues the whole time. I'm not sure exactly what could be causing it. Details on my grow...

Medium: Cyco Coco (70/30)
Method: DTW
Nutrients: Jack's in the 3-2-1 mix. Feeding at 800-900ppm (1.6-1.8 ec)
Fertigation: Automated 4x daily. Each feed gets 10%-20% runoff

A couple of weeks into flower, I started noticing some nutrient burn. I measured runoff EC and it was close to 4! I was surprised because I'm feeding at a lower ec than is even recommended with Jacks, and I've been careful to fertigate frequently to keep the medium from drying out. I have increased the fertigation over time because I might have been under-feeding in the beginning though.

After I discovered the EC issue, I flushed with RO water with some SLF-100 and that brought things back down into range. Since then, I've been testing runoff EC pretty regularly and it's always creeping up slowly. I've ended up having to flush every couple of weeks as a result.

I'm a little stumped why this keeps happening. I've even dropped the EC in the reservoir and increased the fertigation events and that doesn't seem to have helped at all. From what I have read, these steps should have helped keep it in range by running more volume through the medium.

Any ideas on what could be happening? The only theory I have was that the initial buildup was pretty bad, and I never got it properly flushed. But if that were the case, wouldn't the increase in waterings plus the drop in feed EC helped bring it back down? Or does buildup always get worse if you don't get it flushed all the way out?

Stumped on this one. Any help is appreciated.

P.S. Plants look great. Just a little bit of burn from the initial EC spike I think...

Flexnerb · Oct 6, 2020

Did you measure your ec prior to planting anything in the pot?

Im not a coco grower. Ive heard EC straight out of the bag can be high..

Im going to be watching this thread..i might try coco in the future...did the tupur stuff once a few yrs back and always got high EC runoff and nutrient def/toxicity a lot...lol...found out i wasnt fertigating enuff and too much..it was a cluster fuck....got a few ounces from a 5 ft plant. Should have been more

growlo_b · Oct 6, 2020

Flexnerb said:
Did you measure your ec prior to planting anything in the pot?

Im not a coco grower. Ive heard EC straight out of the bag can be high..

Im going to be watching this thread..i might try coco in the future...did the tupur stuff once a few yrs back and always got high EC runoff and nutrient def/toxicity a lot...lol...found out i wasnt fertigating enuff and too much..it was a cluster fuck....got a few ounces from a 5 ft plant. Should have been more

I did measure before I started and the EC was very low. I’ve had good luck with the Cyco coco. It seems fairly clean and it comes pre-buffered.

Yeah, the biggest thing I’ve read is to make sure you’re fertigating frequently and getting substantial runoff each time. I’m currently at 4x daily with a large amount of runoff so I should have that covered.

Grownsince95 · Oct 6, 2020

Im not familiar with your nutrients but im also running a high frequently fertigation in coco and had the same problem. Was driving me nuts! but now after some good flushing, a drastic drop in the ppm going in, along with cutting down one feeding... so im at two a day 8 hrs apart.
I personally only do about 5% runoff, if that, each watering so I dont think that's your issue.
I think lights and environs play a big part in what the plants use so each grow room is really different feed wise even strain to strain

Grownsince95 · Oct 6, 2020

I should probably also mention that I gradually weened down my cal mag use. I felt like it was adding a lot of ppm relative to its benefits. Im at about 1/2 tsp per gal now 2 weeks into flower.

Grownsince95 · Oct 6, 2020

Some guys also swear by yucca as a surfactant to get your water "wetter" but im not there yet. So many things to look into ...it made my head spin

Flexnerb · Oct 6, 2020

growlo_b said:
I did measure before I started and the EC was very low. I’ve had good luck with the Cyco coco. It seems fairly clean and it comes pre-buffered.

Yeah, the biggest thing I’ve read is to make sure you’re fertigating frequently and getting substantial runoff each time. I’m currently at 4x daily with a large amount of runoff so I should have that covered.

If you lowered your EC by say 20 30% woukd that mess with the growth?

Aqua Man · Oct 6, 2020

Size and type of pots as well as humidity and temps?

Terpz719 · Oct 6, 2020

I think you're overfeeding especially if you're feeding 4X a day. When you're fertigating the EC doesn't need to be as high. Just as a point of reference, I'm running coco/perlite, DTW, no supplemental CO2, around 40 watts per square foot, and feeding 3X a day @ EC 0.7. Even that is a bit too strong for one of the strains I'm running.

I still consider myself new to coco, and it took me a while to get my head wrapped around it. My current thinking is the plants don't need water and nutrients necessarily to the same degree. Sure they correlate, but depending on a lot of factors they probably need more water than nutes. So we have to supply water multiple times a day to keep them happy, but it doesn't mean they need a ton of food too.

Remember photosynthesis requires water, light, and CO2. Nutes aren't in the equation. I think it's easy to way over do nutes. Based on what I've seen, the acceptable run off ppm is ±100. Personally, I prefer to see the run off to be less than the input, but that's just me.

growlo_b · Oct 6, 2020

Aqua Man said:
Size and type of pots as well as humidity and temps?

3Gal fabric pots. Temp 69F at night, 77F during day. Humidity around 65%.

growlo_b · Oct 6, 2020

Terpz719 said:
I think you're overfeeding especially if you're feeding 4X a day. When you're fertigating the EC doesn't need to be as high. Just as a point of reference, I'm running coco/perlite, DTW, no supplemental CO2, around 40 watts per square foot, and feeding 3X a day @ EC 0.7. Even that is a bit too strong for one of the strains I'm running.

I still consider myself new to coco, and it took me a while to get my head wrapped around it. My current thinking is the plants don't need water and nutrients necessarily to the same degree. Sure they correlate, but depending on a lot of factors they probably need more water than nutes. So we have to supply water multiple times a day to keep them happy, but it doesn't mean they need a ton of food too.

Remember photosynthesis requires water, light, and CO2. Nutes aren't in the equation. I think it's easy to way over do nutes. Based on what I've seen, the acceptable run off ppm is ±100. Personally, I prefer to see the run off to be less than the input, but that's just me.

Interesting. From what Jack's recommends and what I've seen others do in coco DTW, they usually target around 2.0 EC. I'm feeding way under that.

Aqua Man · Oct 6, 2020

Think you have some great responses here.

Have pics to help see what going on?

You should be fertigating with about 500-600ml per plant. Of that 10-20% should come out as runoff. 50-100ml

If you give them 500ml of nutrient solution and get no runoff then you need to increase the frequency

I would check this first

Aqua Man · Oct 6, 2020

growlo_b said:
Interesting. From what Jack's recommends and what I've seen others do in coco DTW, they usually target around 2.0 EC. I'm feeding way under that.

Never go by recommended. I would say 600-800ppm is the sweet spot for soiless and hydro

growlo_b · Oct 6, 2020

Aqua Man said:
Never go by recommended. I would say 600-800ppm is the sweet spot for soiless and hydro

Agreed but that's the odd thing. I've been around 800-850ppm. I guess I could try lower.

Aqua Man · Oct 6, 2020

growlo_b said:
Agreed but that's the odd thing. I've been around 800-850ppm. I guess I could try lower.

Do the next feed manually and give 500ml at the regular time or catch the feed and measure how much you are getting then manually pour it and check runoff. Once its set you know how long you need the timer to reach 500-600ml. Then you just need to adjust the frequency to get the proper runoff each fertigation.

Terpz719 · Oct 6, 2020

growlo_b said:
Interesting. From what Jack's recommends and what I've seen others do in coco DTW, they usually target around 2.0 EC. I'm feeding way under that.

I hear ya. With Canna, Jacks, and Mega Crop I've always fed way, way under recommended. Except for my first run, even though I was a fair amount less than recommended I still ended up way over feeding. Each grow environment and stain are different. Everyone says let the plants dictate what they want, which I agree with, but it isn't the easiest thing to learn how to hear them. It takes time. You'll get it.

Enforcer · Oct 6, 2020

I’m growing the same way. I think your EC is a little high. I would recommend bringing it down to 1.0. I think 4x a day is fine. I’ve done up to 6x a day in 3gal fabric pots. Yucca is great as a surfactant. It’s just a pain to mix in powder form. I mix the powder into a small amount of warm water to dissolve the powder, then add to the res.

For salt buildup, which I feel does happen to some degree no matter how many times you fertigate. I use Recharge once a week by hand. Just RO water, about 150ppm of calmag, and the microbes. Flush all the pots well and then I resume normal auto feeding. This once a week treat does two things for me. Keeps the EC of the coco low, and introduces beneficial microbes to the root zone. The plants love it.

savagenovelties · Oct 6, 2020

Hey just some food for thought:
Try canna nutes. Specifically designed for coco
And buy 2 meters. Coco is very ph strict so precise ph is a must. 2 meters leaves no doubt. Feed from the bottom not the top. A few reasons why. No bugs can lay eggs in your medium & don’t say you don’t have bugs cause we all have em. And let the plant uptake nutes don’t force feed coco or use any auto watering method it’s a waste of nutrients and a lazy way to grow in coco. Feed coco by the weight of your plant. If it’s heavy it doesn’t need watered. If it’s light depending on size could be disastrous. Never let coco go too long without water when the plant is in flowering. They can really drink. Example: starting week 5 of my gelato flowering I have to feed morning and evening they drink that much. Only strain I’ve had to feed twice a day in flowering

Aqua Man · Oct 6, 2020

gotthatkill4u said:
Hey just some food for thought:
Try canna nutes. Specifically designed for coco
And buy 2 meters. Coco is very ph strict so precise ph is a must. 2 meters leaves no doubt. Feed from the bottom not the top. A few reasons why. No bugs can lay eggs in your medium & don’t say you don’t have bugs cause we all have em. And let the plant uptake nutes don’t force feed coco or use any auto watering method it’s a waste of nutrients and a lazy way to grow in coco. Feed coco by the weight of your plant. If it’s heavy it doesn’t need watered. If it’s light depending on size could be disastrous. Never let coco go too long without water when the plant is in flowering. They can really drink. Example: starting week 5 of my gelato flowering I have to feed morning and evening they drink that much. Only strain I’ve had to feed twice a day in flowering

Sorry but I could not agree less with this.

savagenovelties · Oct 6, 2020

And one more thing many don’t know. Coco has bugs that can’t really be seen. I throw my bags 10 at a time into my deep freezer. It kills any and all bugs that are collected in the bagging process.

Runoff EC always creeping up

Runoff EC always creeping up

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