Rockwool

[sweetnug]

Wanted to get a few ideas about rockwool. I am familar with hydroton and hydro. I am starting 6" Rockwool cubes in a 3x3 table, ebb & flow. Just wondered how often to set timer on during lighting. Think 1-2 per day but not 100%. Any suggestions would be appreciated.

 

[NorCalHal]

Well, starting out, you can flood 1-2 times with those 6" cubes, as they retain water pretty well. As the plant gets bigger and roots start blasting out of the cubes, then yes, you must flood more often to ensure the root mass does not dry out.

 

[sweetnug]

Thanks a lot man. Thats what I figured just wanted to get a professional opinion. I am vegging them 10 in. before 12/12. You think that 4" cubes would suffice next time???

 

[Shockeclipse]

I'm no expert with e&f but I would imagine you could use a smaller cube if your water times were more often. Small cube vs big cube. Small cubes wont hold as much and for as long as the bigger cubes?

 

[DirtySouth]

I've grown them BIG in those 4" cubes.Cover the top(moldy green slime if not)and its WAY better to put a layor of hydroton pellets down then add rockwool cubes then place your 4" on top,add hydroton to the side and presto.

 

[sweetnug]

With the 6in cubes should they be real dry or moderately dry before the next watering. They seem to be staying pretty wet and I may have to cut back the length of cycle since drainage (drying) is very important.

 

[stonegroove]

i water my 4" cubes once a day, any more and my plants droop

 

[JBonez]

what makes marijuana root systems the happiest? You have to know the answer to that question BEFORE you choose a medium.

With that in mind, what medium provides the best aeration and yet still contains enough moisture to allow the roots to uptake nutrient???

HYDROTON.

Rockwool absolutely needs less watering than hydroton, as it retains water more effectively.

The trade off is less oxygen, you see, for example, in ebb&flow the roots spend very little time actually submerged in an oxygenated nutrient solution.

after the flood cycle, due in part to the porous nature of hydroton and the space between the hydroton, the remaining moisture is enough to sustain the plant until the next flood cycle, but in the meantime, the amount of oxygen available in hydroton after a flood cycle can be rivaled by no other medium.

From a mathematical perspective, and knowing the needs of mj, Hydroton makes the most sense.

My buddy uses 6" cubes on top of slabs and he can only water ONCE a light cycle or else his plants suffer overwatering as the rockwool holds so much of it.

any hydro is faster than soil, but imvho, i am about to harvest well over 2lbs with 1400w of light in ebb&flow.

This is my first grow and out of a somewhat shaky algorithm ive deduced, based on purely anecdotal evidence, No other method of hydro can be as effective, fast or easy.

DWC, my problem here is this.

res temps, absolutely must remain at least 68 degrees, this is the best range for oxygen saturation and is critical for the roots to be able to use this oxygen.

A dwc container takes up space, sure a single plant grow in dwc is a great way to go, and i would my self. But if you want a few plants, a flood table is the way to go.

Im not even going to get into aeroponics for two reasons,

1. Never tried it, plus i hear ph flux is a pain in the donkey.
2. Sure, aero is THE MOST EFFECTIVE at water/air ratio, but this setup requires acute attention, and growing shouldnt be a hassle.

Bottom line, Ebb&Flow with hydroton is the easiest thing ive ever tried, lowest maintenance and keeps me out of the grow room so i can live my life not worrying about ph flux (little ph flux is beneficial, so i let it go between 5.5-6.1 and then adjust backwards back to 5.5, one point a day.

enough babbling, hope this helps.

 

[DirtySouth]

I'll help ya improve on your bomb set up. Add 1/2 1/2 hydroton and R.W.mini cubes. Then from your ebb (from the pump) add a drip.
Easy as pie. Drip is way more efficant.1/2 the water in the res. 1/2 the nutes to raise the ppm. R.w. helps stable ph, it makes for less waterings.The cube hydroton mix is the bomb.Nice-n-airy while retaining enough moister for less waterings-ph mishaps.
I know you did great, but this is food for thought!

 

[JBonez]

I'll help ya improve on your bomb set up. Add 1/2 1/2 hydroton and R.W.mini cubes. Then from your ebb (from the pump) add a drip.
Easy as pie. Drip is way more efficant.1/2 the water in the res. 1/2 the nutes to raise the ppm. R.w. helps stable ph, it makes for less waterings.The cube hydroton mix is the bomb.Nice-n-airy while retaining enough moister for less waterings-ph mishaps.
I know you did great, but this is food for thought!

i absolutely loved your post!

And while thinking about it, it does make sense, trade off slightly less oxygen for slightly more nutrient, hmm..... think ill try that on one of my flowering chambers, if fact, im going to.

My only concern is the rockwool buffering the ph to high, to fast.

You see, when i fill my res, add nutes and finally ph adjust, i generally start around 5.6. By the next day it is a point higher, and again the following day. As it rises to 6.1, i back adjust to 5.8 where the ph pretty much remains stable on its own, whether i add ro water or not, the ro water assimilates with the ph of the res for whatever reason, and buddy, im not complaining, after a few days of refreshing my res, i pretty much just observe for the next week or so, topping off maybe once or twice.

Total time spent in the grow room a week, about 3 hrs.

total time spent in the tent watching, observing and examining the plants, about 8hrs a week, ballpark.


but hey, it cant hurt, ive had unreal cloning and germination success in rockwool, i just soak overnight and viola! Rockwool is great for cloning, just use the mini cubes, not the plugs.

Rockwool plugs are cut down the middle on one side and doesnt hold firm against the cuttings, so rooting takes longer.

seeds also need a solid footing in rockwool, so the plugs are a no no.

And when germing in little rockwool cubes, ph some water to 5.0, i do and it works, then soak em overnight and they are great.

make sure to place seeds tips up!!!!! good growers know this.

also, rockwool cubes have a premade hole in them for cuttings and seeds.

the holes are too deep for seeds, so turn the cube upside down and make a very shallow hole of your own and place the seed tip up just below the surface so it almost looks exposed, but still covered.

the cubes hold moisture for a week before needing watering for the first time, so be mindful of the moisture level.

as for mature plants, i urge you to look away from big rockwool cubes and slabs, but hey, if it works for ya, go for it, and ive seen huge successful rockwool slab grows with unreal results, but they were pretty elaborate, something the common grower is not.

hope this helps, and thanks Dirty for the advice, ill dedicate the next Hybrid hydroton/rockwool mini cube grow to you!!

 

[DirtySouth]

sweet!