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

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newbplantgrower420

Well-Known Member
Triplefastaction said:
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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Ive been doing flood and drain with these new and improved. I feel like they keep in way more moisture than the old grey ones. Basically I flood until near the top of the 6 inch hugo block and gotta wait a few days until it gets almost completely bone dry. Right before they wilt.

Im thinking of switching to those quick drain pargro blocks for flood and drain so they drain quicker. What do you think?
 
T

Triplefastaction

Well-Known Member
Sorry, never done flood/drain and never used the big Hugos before. I do 4" block on top of unislab, top drip.

Still not sure why you'd want your blocks to get that dry, as that's really the way to grow in soil and not in a hydro system. Plants can grow in water if provided enough oxygen. Oxygen is provided in rockwool blocks by feeding and the capillary action of the water flow. Your roots can stay wet for months as long as you provide oxygen. But when you let the blocks sit for days chasing dryback you just end up drowning the roots. Basically the one way you can overwater a plant in rockwool is to not water it frequently enough, if that makes sense (assuming your plants are 3" tall or so and have a basic root system developed)
 
pegboy

pegboy

Well-Known Member
Triplefastaction said:
Sorry, never done flood/drain and never used the big Hugos before. I do 4" block on top of unislab, top drip.

Still not sure why you'd want your blocks to get that dry, as that's really the way to grow in soil and not in a hydro system. Plants can grow in water if provided enough oxygen. Oxygen is provided in rockwool blocks by feeding and the capillary action of the water flow. Your roots can stay wet for months as long as you provide oxygen. But when you let the blocks sit for days chasing dryback you just end up drowning the roots. Basically the one way you can overwater a plant in rockwool is to not water it frequently enough, if that makes sense (assuming your plants are 3" tall or so and have a basic root system developed)
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Are you connected to the band Triple Fast Action at all?
 
N

nxsov180db

Well-Known Member
newbplantgrower420 said:
Ive been doing flood and drain with these new and improved. I feel like they keep in way more moisture than the old grey ones. Basically I flood until near the top of the 6 inch hugo block and gotta wait a few days until it gets almost completely bone dry. Right before they wilt.

Im thinking of switching to those quick drain pargro blocks for flood and drain so they drain quicker. What do you think?
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Do you feel like you have less roots poking through the bottom of the new and improved blocks?
 
N

newbplantgrower420

Well-Known Member
Triplefastaction said:
Sorry, never done flood/drain and never used the big Hugos before. I do 4" block on top of unislab, top drip.

Still not sure why you'd want your blocks to get that dry, as that's really the way to grow in soil and not in a hydro system. Plants can grow in water if provided enough oxygen. Oxygen is provided in rockwool blocks by feeding and the capillary action of the water flow. Your roots can stay wet for months as long as you provide oxygen. But when you let the blocks sit for days chasing dryback you just end up drowning the roots. Basically the one way you can overwater a plant in rockwool is to not water it frequently enough, if that makes sense (assuming your plants are 3" tall or so and have a basic root system developed)
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I think youre right. I wont let it get that dry. I think the issue Im having is since I flood and drain. I cant keep the WC% stable like drip system.

What happens is when I flood the whole Hugo gets drenched and soggy... its full of water. Then by the time It dries out it takes a 4-5 days. Then I flood again it gets drenched and soggy etc.

You think those QD Pargros would be better for Flood an Drain?
 
pegboy

pegboy

Well-Known Member
newbplantgrower420 said:
I think youre right. I wont let it get that dry. I think the issue Im having is since I flood and drain. I cant keep the WC% stable like drip system.

What happens is when I flood the whole Hugo gets drenched and soggy... its full of water. Then by the time It dries out it takes a 4-5 days. Then I flood again it gets drenched and soggy etc.

You think those QD Pargros would be better for Flood an Drain?
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How high are you flooding your blocks? I don't know if I'm right or wrong but I only flood about 1/3rd the hieght of my 4"x4" cubes and let the rest wick up the rockwool. Works great for me. You will have to top flush prox once a week though for salt build up.

And its actually pretty easy to overwater rockwool when bottom feeding.....
 
pegboy

pegboy

Well-Known Member
Also my plants are always happier when I let the blocks dryback a pretty decent amount.

Current situation....tiny happy plants....9lb 2-14-4.jpg
 
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N

newbplantgrower420

Well-Known Member
pegboy said:
How high are you flooding your blocks? I don't know if I'm right or wrong but I only flood about 1/3rd the hieght of my 4"x4" cubes and let the rest wick up the rockwool. Works great for me. You will have to top flush prox once a week though for salt build up.

And its actually pretty easy to overwater rockwool when bottom feeding.....
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Ya I agree it is easy to overwater RW with f/d. With my 6x6x6 Hugos I flood up to 5 inches of the RW in my new room. I do have salt buildup.

Im going to get those 6x6x4 Cubes next run to just flood the whole Cube every time to avoid the salt buildup.

Do you still get salt buildup yourself flooding that low?
 
J. Rocket

J. Rocket

Well-Known Member
pegboy said:
How high are you flooding your blocks? I don't know if I'm right or wrong but I only flood about 1/3rd the hieght of my 4"x4" cubes and let the rest wick up the rockwool. Works great for me. You will have to top flush prox once a week though for salt build up.
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within 1" or less of the top is mfg. spec. as I remember.
4" block= 3" deep flood, 6" block=5" flood, etc.
you want the block soaked throughout for the most effective rinse/drain.
 
pegboy

pegboy

Well-Known Member
J. Rocket said:
within 1" or less of the top is mfg. spec. as I remember.
4" block= 3" deep flood, 6" block=5" flood, etc.
you want the block soaked throughout for the most effective rinse/drain.
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I have seen that. Never worked out for me (even with 4" blocks). I went with other ebb and flow suggestions with respect to watering 1/3 of the block and flushing weekly. I feel (in my situation anyway) I have way more control and the roots never starve for oxygen.

Edit: I've never grown with the bigger blocks but I assume its pretty much the same.
 
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P

phantom grower

Member
Plants look healthy ish, some minor deficiencies likely caused by pH imbalance in the rockwool. Runoff ppm is 4-500 but the pH is in the high 6s 6.8ish. I'm going to try the obvious and lower my feed pH to about 5.5 and get a couple days of multiple feedings/day to lower that. But if that doesn't work does anyone have any other suggestions?

Also I'm working on getting a flood tray so I can run a true DtW system but I'm not sure where to start after that. I assume I can lift the tray a foot or 2 off the ground with some homemade contraption. I'll prolly do it with PVC. Seems cheap enough, then run PVC from the drain hole to something to drain the water from the tray. If anyone has any suggestions or advice I'd love to hear.
 

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N

newbplantgrower420

Well-Known Member
J. Rocket said:
within 1" or less of the top is mfg. spec. as I remember.
4" block= 3" deep flood, 6" block=5" flood, etc.
you want the block soaked throughout for the most effective rinse/drain.
Click to expand...
phantom grower said:
Plants look healthy ish, some minor deficiencies likely caused by pH imbalance in the rockwool. Runoff ppm is 4-500 but the pH is in the high 6s 6.8ish. I'm going to try the obvious and lower my feed pH to about 5.5 and get a couple days of multiple feedings/day to lower that. But if that doesn't work does anyone have any other suggestions?

Also I'm working on getting a flood tray so I can run a true DtW system but I'm not sure where to start after that. I assume I can lift the tray a foot or 2 off the ground with some homemade contraption. I'll prolly do it with PVC. Seems cheap enough, then run PVC from the drain hole to something to drain the water from the tray. If anyone has any suggestions or advice I'd love to hear.
Click to expand...
What would happen if I were to feed the bottom 2 inches of a Hugo and never top feed besides salt buildup from drybacks. The roots would still be fine right?
 
pegboy

pegboy

Well-Known Member
newbplantgrower420 said:
What would happen if I were to feed the bottom 2 inches of a Hugo and never top feed besides salt buildup from drybacks. The roots would still be fine right?
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Salt build up which will lead to very low PH in the block and nutrient lockout.
 
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R

Roguedawg

Well-Known Member
Just get coco if you can drain to waste, if you have to recycle try straight perlite. Either one will solve your pH and o2 problems. I see people trying to crop steer all the time now, before they can get through a whole cycle with healthy plants. If you can not get through the whole grow with no stress you are already crop steering.
 
P

phantom grower

Member
I owe a big thank u to anyone that has given me advice! Day 1 of flower will be tomorrow and the girls look really healthy. They have absolutely taken off since installing the auto water system, even in sub-optimal conditions so I'm even more excited for wen I get my room in check
Thank u again!
 

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