Rockwool cubes and hydroton?

Discussion in 'Hydroponics / Aeroponics' started by selfmedicator462, Aug 10, 2017.


    selfmedicator462 Well-Known Member

    Im setting up my first flood and drain grow (mainly grew in soil or peat) and have decided on using 6" rockwool cubes. My question is should I fill the area in the tray between the cubes with hydroton? Ive read to use a coco mat as well. Or do i need not worry about it?

    SouthCross Well-Known Member

    What is your green thumb telling you? We can offer advice but I believe you are gonna try it regardless. You run your grow. Hook it up and see what happens. The expanded clay pellets won't hurt a thing.
    Organic Miner

    Organic Miner Well-Known Member

    I think it will be cleaner with hydroton, but what do I know? I use cubes and hydroton in my RDWC. It's up to you.

    Airwalker16 Well-Known Member

    Rockwool stunts early growth. I'd much rather suggest you plant directly into net pots of hydroton and put those into a tray full of loose hydroton. EXPLOSIVE growth.
    OneHitDone likes this.

    jonsnow399 Well-Known Member

    I've never experienced that, fastest growth i have ever seen was with rockwool.
    Xs121 likes this.

    adower Well-Known Member

    Use net pots and hydroton. Skip the rockwool. It's very easy to overwater and stunt your plants.

    jonsnow399 Well-Known Member

    never had that problem either.
    Xs121 likes this.

    FennarioMike Well-Known Member

    Here's the thing with any sort of rooting plug and DWC and one of the most common causes of plant failure. If the rooted plug is too low in the hydroton then it stays too wet which starves the O2 and the plant first shows overwatering symptoms, deficiencies, damping off at the stem and the plant eventually dies. One solution is to keep the plug sticking 1/2 way up out of the hydroton so that it is enough above the wet line that it can drain. Don't forget, the splashing action gets the hydroton wet well above the fluid level.

    Also, keeping the fluid lower helps - but then you lose useable root mass. Wherever there is an air gap, the roots become big thick ropes which are really just extensions of the stem, and aren't exchanging nutrients - they only transport. So you lose that % of potential root mass.

    I know that a lot of people use them without issues - but a lot do end up with issues. I was one of them and I figured out how to not use them at all. It's just one less point of failure.

    Here's what I have learned to do and how I avoid all of that. I made a super cheap bubble bucket and fitted some 2" PVC adapters on the lid and popped a neoprene ring in it. I just use tap water - not even pH'd - and put the seedling or clone in there until the roots are about 6". If it gets to the 3rd set of leaves then I'll add 1/4 nutes. But then I just transplant into the netpot and drape the roots down through the bottom and backfill with hydroton. Now you're good to go with roots already out of the netpot and ready to take up nutes. No rooting plug or those potential headaches, no top watering until roots show through... I also keep my fluid levels 2" above the base of the netpot for the entire grow. This causes lateral fine root growth from the whole sides of the netpot on down. No giant cord roots and much more root area. More root area = more upper growth.

    These pics are clones, but for seedlings I sprout in wet paper towel until the root in maybe an 1 - 1 1/2" - enough that I can stick the taproot through the neoprene ring with the top sticking out. Then grow it out it the bubble bucket.

    IMG_2795 2-2.JPG IMG_1449-2.JPG IMG_1492-2.JPG IMG_1284-2.JPG
    selfmedicator462 likes this.

    selfmedicator462 Well-Known Member

    I guess what i was wondering was in a flood and drain youll have some exposed roots in the tray. I always thought roots and light wasnt good. Mind you ive never grew in hydro of any kind so im learning. Also do you need to cover the top of the cubes?

    bryan100030 Member

    That is a good question. I would really like to know the answer to this as well, cause I seem to keep getting some sort of algae...Also. If any one can tell me what to do about this problem Iam experienceing, please help. I think I have some how got root rot on my special queen #1 and now she is showing (I THINK) signs of a Copper Deficiency? Here is a picture of here, its been about 3 weeks in the tent, very slow growth. PLEASE HELP GUYS/GIRLS.

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    ThaMagnificent Well-Known Member

    I get the green algae on my roots in the flood trays but it doesn't seem to effect the plants because these are older roots. I'm guessing it's similar to the DWC guys with the balls of roots always submerged in their water?

    FennarioMike Well-Known Member

    Because there's no light that gets into a DWC, there is no algae
    Budley Doright

    Budley Doright Well-Known Member

    Once the roots are established overwatering is not a problem with rock wool but yes as a seedling it is very easy to overwater, so easy that I see it lots on here. I flood twice a day when using rock wool but allow the water to hit the bottom of the cube. I would not allow the cube to be exposed and cover it with a layer of balls or it gets all nasty and algae covered

    Flagg420 Well-Known Member

    In DWC for sure, rockwool slows down early veg hardcore.... just not a good air/water mix er something, I did it for a long time, mostly for the stability 6" blocks offered....

    Now I just use a rooting plug of some kind, root riot, root shooter, etc. and drop it in there w/ the hydroton....

    Clones after several years are now just spray cloner, no addatives, plain RO water, and when they root, straight into hydroton, no cubes, no rockwool, nothing.

    All this is for DWC mind you in a flood n drain system, I imagine the rockwool holds up better... not DWC tho.. rockwool is just evil...
    Airwalker16 and Budley Doright like this.

    selfmedicator462 Well-Known Member

    i germinated my seeds this time right in the rockwool starter cubes. WOW! im ditching the paper towels. These things were up in 2 days. No soaking either. Presoaked the cubes in 5.5ph water and stuck the dry seeds right in. In about a week i had visible roots. So much quicker and less steps.

    zypheruk Well-Known Member

    Cover your flood table with white panda film and kill all light getting to the roots. Nice moisture rich environment for the roots.

    selfmedicator462 Well-Known Member

    So no hygroton? Here's my seedlings. Northern lights. 20170913_124400.jpg 20170913_124355.jpg

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    Budley Doright

    Budley Doright Well-Known Member

    Just wondering how the girls are doing? Yes you have root issues. Could be water temps or over watered as in always wet. before I chilled my water I used hydroguard which seemed to fix the issues and keep them away. Sadly I cannot get it anymore here unless I pay crazy prices.

    weedemart Well-Known Member

    6'' rw cube is an overkill, grodan recommand max 4'' for flood and drain application. the 4x4x4 seem to be the ideal choice.
    you dont have to fill the table, just cover your table with a white panda, as zypheruk said and it will stop root pruning and keep your medium/root clean of algae. dont forget to cover your rez.

    hydroton is more user-friendly but if u can deal with rockwool, it will reward you. most of time issue with rockwool is lack of oxygen. you need to understand how rockwool works; its completly inert ,no nutrients,neutral ph and it retain a lot of moisture.It has the property to wick nutrient very easily, as a sponge and drain slowly based on the moisture gradiant . ideally you want wet-dry cycle and set your flood level 1/4 to 1/2 cube height. never let the cube go bone dry and the cube have to seat on leveled surface to drain properly. ph should be set a 5.5-5.8. water/room temp between 65f-72f prevent disease.
    Xs121 likes this.

    selfmedicator462 Well-Known Member

    yeah when i ordered they were out of 4" so i got a case of 6".

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