Rockwool PH and other challenges... Automated Top Feed Drip...Crop Steering

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phantom grower

Member
I have a question I know someone will be able to answer. I am reading that preferred shot size for veg steering is 1-3% of total water held while fully saturated? Now if that's right and if my math is right then I would be giving 5ml shots multiple times a day IF my substrate holds 500g of water? This is all in optimal conditions of course and it varies from plant to plant and environmental conditions as well. But from a base standpoint does it sound about right?
 
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phantom grower

Member
Triplefastaction said:
Your concept and math (for the example provided) are accurate, as 1ml of water weighs 1g. So 5ml to 15ml shots in your example, depending on your dryback. Good luck.
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Thank you!! And this really comes in to play only wen the root zone is fully developed or developed enough too suck up that water and nutes right?
 
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Triplefastaction

Well-Known Member
phantom grower said:
Thank you!! And this really comes in to play only wen the root zone is fully developed or developed enough too suck up that water and nutes right?
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For the most part, yeah. Theoretically, if your shot sizes exceed your dryback you'll just get runoff at every feed, which isn't the worst thing in the world, it's just deviating a bit from intentional crop steering.
 
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Triplefastaction

Well-Known Member
phantom grower said:
Also, is the 5-10% dryback from full sat? Or is it from the target water content range im seeing
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My experience is rockwool, and in that case it's a always discussed as a percentage of capacity, since in true crop steering you would bring your media up to and beyond full capacity once per day.
 
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phantom grower

Member
Triplefastaction said:
For the most part, yeah. Theoretically, if your shot sizes exceed your dryback you'll just get runoff at every feed, which isn't the worst thing in the world, it's just deviating a bit from intentional crop steering.
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Thank u for all your help..seriously lol. I think for my first rockwool grow I'm going to try to follow "conventional" steering methods but without an auto feed system it might be more difficult, so I may resort to feeding till runoff everytime it needs it. Who knows, I'll experiment a little.
 
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Qsound

Active Member
Triplefastaction said:
Qsound - how is your flowering progressing?
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Hey Tripple! thanks for checking in....Been out straight. I haven't flipped yet. I just posted in plant problems. Chasing a deficiency that's kicking my ass! The post is titled Cant figure it out! Have a look if ya get a chance!
 

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phantom grower

Member
Okay so I've realized that I do not know shit about shit wen it comes to rockwool but I am sending it anyways. So I have been reading some info that grodan has about their blocks. U know the how-to guides and wat not.

I read that the desired water content for vegetative steering is from like 40% to 65% of the total block wen fully saturated. Could someone explain that to me? I think I know but I'm not sure. If the block weighs 3300ish grams full sat and at 65% WC it would be 2200ish grams. Now wen we talk 5-10% dryback are we talking 10% from full sat or from that desired water content?

So essentially the overnight dryback puts the block under that desired water content which happens to be 2200g and the slow feeds throughout the day are to bring it back up to that WC and NOT full sat? Or should I be trying to hit full saturation by the end of the day
 
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Triplefastaction

Well-Known Member
Here's how I understand it, anybody please correct my mistakes or errors ....

The crop steering literature all assumes you use the standard 3 prong sensors used by the Grodan, Ayrro, Growlink systems. These sensors typically show a WC of 60-70% when the rockwool is fully saturated and showing runoff. I guess I'll make a leap of faith and say the remaining % is fibers and air, but who knows, may just be the measurement method. Whatever it is, the sensors will never read 100% saturated and the fully saturated % decreases as the root mass expands and takes up space.

So if you are trying to do all of this manually, assume 65% is the same as 100%, if that makes any sense and dryback from there. But unless you have an irrigation controller that will automate your shots based on the rockwool PWC, I think you'll end up driving yourself crazy chasing specific percentages. The concepts are still good though.
 
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phantom grower

Member
Triplefastaction said:
Here's how I understand it, anybody please correct my mistakes or errors ....

The crop steering literature all assumes you use the standard 3 prong sensors used by the Grodan, Ayrro, Growlink systems. These sensors typically show a WC of 60-70% when the rockwool is fully saturated and showing runoff. I guess I'll make a leap of faith and say the remaining % is fibers and air, but who knows, may just be the measurement method. Whatever it is, the sensors will never read 100% saturated and the fully saturated % decreases as the root mass expands and takes up space.

So if you are trying to do all of this manually, assume 65% is the same as 100%, if that makes any sense and dryback from there. But unless you have an irrigation controller that will automate your shots based on the rockwool PWC, I think you'll end up driving yourself crazy chasing specific percentages. The concepts are still good though.
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That makes perfect sense. Thank you! Because I figured I would need a daily or semi daily water till runoff to make sure everything is still balanced.

That's why I assume getting an automated feed system is super beneficial because right now I'm having to do larger shot sizes less frequently and I havemt really even hit full sat, not on the 6x6s. I assume that more shots more often with less water per shot is preferable.

I feel like I will suffocate my girls if I feed to full sat everyday and at night get that 10% dryback then gradually getting to that full sat over x hours. But I also read that this "trains" the plants to enter a stage of more vigorous growth and to spread it's roots more. Idfk wat to think. But I think I have a decent understanding of how it works. It's just the little stuff
 
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Triplefastaction

Well-Known Member
After you get to full saturation, you have little mini 1-3% drybacks throughout the day, but you provide "maintenance" shots to keep your rw fully saturated to offset those drybacks.

You'll need to figure out when your last feed of the day should occur (prior to lights out) In order to achieve your overnight dryback goal.
 
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phantom grower

Member
Triplefastaction said:
After you get to full saturation, you have little mini 1-3% drybacks throughout the day, but you provide "maintenance" shots to keep your rw fully saturated to offset those drybacks.

You'll need to figure out when your last feed of the day should occur (prior to lights out) In order to achieve your overnight dryback goal.
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Thank you!! U have been a huge help!
 
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newbplantgrower420

Well-Known Member
what happens if you dryback the blocks to 10-20%? Everyone always suggests 30-40% in the crop steering charts for Generative Stage. is too much dryback bad for roots?
 
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Triplefastaction

Well-Known Member
newbplantgrower420 said:
what happens if you dryback the blocks to 10-20%
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You are going to have massive spikes in ph and EC of the block which is going to make it harder to grow anything and at that point you'd likely see plant wilt from lack of moisture. A 10-20% saturated rw block is dry/light AF. And if you are fertigating correctly there's really no way to get that much dryback in a 24 hour period.

More importantly - and This is per Grodan literature and I can't explain why - the structure of the RW fibers supposedly changes after an extreme dryback and the block will never saturate to the same % as new. Again, that's what they say, I dunno.

Lots of dryback talk, and it's important as it pertains to crop steering. But as far as growing in rockwool, you can grow kick ass plants by top feeding to runoff every hour during lights on, keeping your blocks fully saturated and just letting them dryback at night, then start back feeding to runoff the next morning. Its nute wasteful, but it grows nice plants, and is probably the best bet if someone is just starting rockwool.
 
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