Algae will not form on your rockwool top surface if it were not wet constantly. If you water from the bottom with a flood system, the media tops will stay dry. Pellets won't stop algae. Nutrient solution + light + algae spores (available pretty much everywhere on the planet) = green slime. If you can't keep it dry, block the light to it with a disc of pandafilm that has a hole cut for the stem in the middle and a slot to fit the disc over the media tops.

Your hydro shop I'm sure was pleased to sell you something/ANYTHING to fix your problem. It doesn't sound like they were as ready to help you troubleshoot your conditions. No profit in that! Quite a lot of the 'magic sauces' on the shelf in a hydro shop are made mainly of water and profit and have funky labels promising all manner of things. The profit is squeezed out before you get the jug out of the shop... Most problems in a grow are related to process and procedure, not lack of a magic sauce cure. I laugh every time I see a bottle of 'stop wilt.' I cry when I see someone BUY that bottle. There goes a person whose flowering plants have root problems or they've got droopy clones, both usually caused by overwatering- and a bottle of sauce ain't gonna fix it.
You need to learn to water by the feel of the weight of the pot. You are looking to water when the pot 'feels light.' That specifically means that about half to 2/3 of the water stored in the media has been removed by the plant.

You can learn the feel with some degree of accuracy if you know the weight of the dry media. Saturate some dry rockwool media like you are presently using, let it drain a couple of minutes. Weigh it and subtract the dry wt from the wet wt. Since water weighs 1g per ml, if your calculated water weight is 2kg, you know there is 2L of water in the media. You'd water that media again when the water wt drops 750g-1kg.

Since you've transferred your small cubes into the 4" cubes, water them no more than 1x/day and don't expose rockwool to DWC mist. Treat the nutrient soln with 50% grade H2O2 at 1ml/L every 3-4 days.

When your plants recover and drop some roots out of the bottom of the cubes. then they will be ready to go into a pot full of pellets. There should be no less than about 1" of pellets between DWC mist and the RW cube. A single layer of pellets is not sufficient. If necessary, get bigger netpots.

Yep! Nope! If anything, it will speed pathogen growth. What's good for plants is also usually good for fungus & algae. That's because you're not using anything for pathogen control or what you are using isn't working. Treat the nutrient soln with 50% grade H2O2 at 1ml/L every 3-4 days. That will stop the goo. H2O2 will destroy dead organic matter and microbes, releasing oxygen in the process, right where you need it most, in the rootmass.

I reckon you'll get roots out of the bottoms of your 4" cubes in 7-10 days. I'd water them by dipping the bottom of the cube in a bucket of aerated nute soln, to mimic a flood system, until they have roots out of the bottoms of the cubes.

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone

Al,

I originally went to the hydroshop to pick up some h202, but when I was talking to the employee about it, he said that the h202 would not be a good fit with my Fox Farms nutes. Is this true?

Also, I will try the dipping method. How long should I let the cube sit in the soln? Until it feels heavy enough? Should I see wet on the top of the cube?

Thanks for all your help.

If Fox Farm nutes are organic based, he's right. H2O2 will break down organic nutes. You have a whole new set of problems if you insist on use of organic nutes. Standard nutes, made from things like ammonium nitrate as opposed to guano and compost 'tea,' are not affected by H2O2. It is infinitely easier to maintain an op running on regular nutes. Pathogen control in organic ops requires use of competing organisms as opposed to periodic dosing with H2O2.

Watering rockwool can be a bit tricky. Behaves a lot like a kitchen sponge. If it has been allowed to go completely dry, it will be somewhat water repellent. If there is some moisture remaining, it will pick up water readily. The amount of water in the material will affect how quickly it will pick up water. If your cube is slightly damp, dip for only a few seconds. You'll feel the cube lose buoyancy and get heavy very quickly. If the cube has been allowed to dry out too much, it will try to float. Trick is to not allow your cube to go so dry that it becomes water repellent.

If you see water wicked to the surface of the cube, it is saturated. RW needs to be damp but not saturated. You can remove a bit by shaking the cube with a snap of the wrist over your bucket.

Think 'damp' not wet or saturated. Water again when about half the water weight is gone. Try to avoid letting the cube go dead dry.

I know this sounds complex, but with some practise, you'll get the hang of it.

You're working with 4" cubes at the moment, but in future, I'd suggest you use only 40mm wrapped cubes, with a plan of later nesting them in pellets (once they've got roots out of the bottom of the cube) and watering them with your existing DWC arrangement.

I do think that a flood system with plants in (regular, solid wall) pots of an absorbent medium or pellets would serve you better in the end. DWC can be fiddly and I would not normally recommend it to a new grower, but since you have one set up, we'll see if we can make it work for you.

No worries, hope we can make this sit up & bark for you.

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone

hey lets start over with explaining this dwc. put your net pots in something like a rubbermaid tub with holes cut out. now hot glue 1-2 air stones hooked up to 1-2 tiny tiny 5 dollar petco air pumps down to the bottom of the rubbermaid container. now run your hoses up along the sides with optional hot glue to a point where you can drill a hole and feed them out above where water will ever bubble up to (very high bubbling believe it or not). now fill your make shift rubbermaid resevoir up until just below the netpots bottoms whereever they meet. (obviously the more water the less u need to dump and remix a batch of nute water (like every 2 weeks)).

2 pumps i like incase one breaks down.

keep light away from the water and even some even like keeping it off of the grow rocks and cubes. the extreme damp conditions make for rapid mold growth.

Do you think I should ditch my Fox Farm nutes? It says they are organic on the cover. Any other nute you'd recommend instead?

So am I just aiming to keep the amount of water @ between 50 and 100 percent?

I originally started with 22mm cubes surrounded by pellets. I posted about my plants in another thread and a member recommended I transplant to 4 in cubes. Now I have 1 in cubes, 4 in cubes, and a bunch of pellets to play with.

I was wondering if there is a significant yield difference in the type of hydro that is used? It seems like people imply that some are higher yielding, but I haven't found anything definitive.

Well, what happened was the first grow journal that I read was a a drip/DWC operation. It was the one that inspired me to try growing, so I wanted to try to copy it. Sometimes I find myself regretting trying to be too ambitious.

My original setup was almost identical to what you have described. The only differences being that I used a 4 in flexi-airtube and a drip system.

Thanks again for all the wisdom you're imparting on me guys!

Being in Australia, it's a little hard for me to make recommendations to you- I don't know what's on the shelf at your local shop. I use Canna nutes, a 2-part type, which is dead-easy to use. Whatever you get, try a 2-part 'standard' (non-organic) nute from a large maker.

Nutes are not complicated stuff; Jim's is as good as Joe's for the most part but large makers produce very large quantities at once, meaning there's less variation between jugs of goo.


Ideally, between 40-60%, if you can cut it that close.

22mm cubes are generally too small. They tend to dry out too fast, particularly when they're kept on a heat mat in your clonebox (which they should be). You'll wind up watering 22mm cubes 3-4x/day, which is a pain. If the cubes are allowed to dry out too much, your clones may wilt or may need to be re-cut if the stem tip dries out.



40mm wrapped cubes are just right. With 40-60% of their water holding capacity, they will get a clone which has not yet set root through 24 hours. They'll give 12 hours water supply for a clone which has set root. Once they set root, their water uptake, as you might expect, goes up sharply.



As soon as clones have set a few good roots out of the cube, they're ready to be flowered.

heh, you can live with the quiet satisfaction that you're keeping some nice Danish fellow at the Grodan factory in a good job.

Seriously, see about getting some 40mm (~1.5"), plastic wrapped cubes.

The most productive hydro systems are the ones which can get the most oxygen to the rootmass. The way to get the most O2 to the roots is by using either a very low absorption media (pots of pellets in a flood system that floods often) or systems which use no media at all (aero, DWC, SWC, NFT) and which provide oxygen through the watering system. All of these systems will produce similar yields, with similar speed.

Rockwool does not permit frequent introduction of freshly oxygenated nutes to the rootmass. Rockwool allows about the same amount of root oxygenation as soil and is broadly similarly productive. However, hydroponic nutrients are generally more bioavailable than organics in soil and thus will produce a bit more yield, somewhat more quickly than soil.

I used pots of rockwool floc for many years. Because I'm a stoned slacker, I wanted the ability to skip looking in on my op for a day if needed. RW holds a lot of water and provides that level of backup. I don't use pellets because they are heavy and hard to dispose of. I've recently switched to Fytocell, which is a bit like crumbled foam rubber. It has a 40% air content and thus can be flooded frequently, but not quite as often as pellets. I flood small plants in Fytocell 2x/day and large plants 3x/day. Fytocell does have some water storage capacity in case I get a slack attack. It does have a couple of drawbacks, though. Crumbs of Fytocell can fall out of the drain holes. The high air content means pots of Fytocell can float. So, I pack about 25-50mm of RW floc in the bottom of each pot before filling the remainder with Fytocell. This allows water to pass through to wet the Fytocell but keeps the crumbs in the pot. The RW holds a lot of water and so weights down the pots when wetted, preventing them from floating.

You were smart to look for a productive op to copy. However, I think the finer detail of the character of different media types escaped you. That's cool, we'll make this crop work and see about something more suitable for your next pass.

RW is not the preferred main medium for DWC or drip watering, as you have unfortunately found. Drip & DWC are intended to provide either frequent or constant watering of low-absorption media. However, the high water storage capacity of RW cubes and their compatibility with heat mats makes them ideal for starting clones.

Once there's roots out of the bottom of the RW cubes, they can be nested in pellets. If using a flood system, the cubes must be 1/2" above the flood level. If using a DWC, there must be at least 1" of pellets between the DWC mist and the RW. The idea is to dampen the pellets so the roots can find and knit into them. Once they are down into the pellets, the roots will enjoy frequent flooding or the constant mist from the DWC.

Alternatively, you could use Fytocell (if available - may not be easy to get in the US) or perlite, which behaves somewhat like Fytocell. A layer of packed RW floc in the bottom of the pots will keep perlite in the pots, same as with Fytocell.

In the short term, water your 4" blocks by dipping in a bucket of aerated nute soln (pretty weak now, maybe 800ppm) which gets treated with H2O2 every 3-4 days. The cubes probably won't need water every day. Don't saturate them, only dampen them. If they are saturated after watering, give them a bit of a shake over the bucket with a snap of the wrist to take out any excess water. Mr Whipple sez - 'Please don't squeeze the rockwool!' Crushes the material and removes what airspaces there are.

I saw you being led down the rosy garden path and couldn't just watch it happen. Happy to let you know what I know.

We'll make this work, please be as patient as you can.

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone

With a DWC system you don't need rockwool, escpecially for cloning... Just a cutting, root hormone, net pot and hydroton.

Yes, you can bodge up your DWC to also do cloning, but you won't be using it for cloning while you have other plants in it. Clones need veg cycle lighting and no nutes while setting root.

any other fine advice for us?

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone

dont pik on him Al it is obveus that smoketoke is a w33d b4R0n like meself and dezervs sum respek!

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Stoney, you're right. Respeck. I'll pull me head in.

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone