This is my first time with hydro, but not my first grow (4 soil harvests under my belt), just to give you an idea of my experience level. Before I explain what my problem is, I should mention a few things about my setup first:

Type: Drip on 15on/45off intervals
Medium: Rockwool/hydroton
PH: Ranged from 5.8 to 6.1 so far
TDS: 1000 uS (700 PPM @ .7 conv)
Res Temp: ~69*F
Res Volume: 10 gal. (currently, will up to 20 gal. as plants bet bigger)
Aeration: Dual output air pump wth two 10" airstones
Nutes: AN 3 part (1-1-1 ratio)
Age: ~3 weeks
Ambient temperature: Lights on - ~78*F, Lights off - ~70*F
Notes: Well ventilated room, air cooled 600w, oscilating fan

Now that I've got that out of the way, I'll explain.

To make a long story short, 3 weeks ago I started 11 seeds in 1" rockwool cubes, after about a week and a half they were all popped and growing with roots protruding out of the cubes. I then planted them in 5" mesh pots of hydroton. For about 4 or 5 days they grew like gang busters, then slowly began to show signs of overwatering (droopy leaves) and have been getting progressively worse over the past few days. Other than the droopy leaves, no other problems are apparent; the plants look otherwise green and healthy, and visible roots look white and fuzzy. I got curious with one of the weaker, smaller ones so I decided to pull it out of the hydroton to see what was up and I discovered that the 1" rockwool cube was soaking wet. From this I can only assume that all the other plants are like this as well and that is probably what is causing the overwatering symptoms (even though the hydroton is just right).

Have any of you experienced this kind of problem. What is the appropriate solution? It'll be difficult if not impossible to remove the rockwool without destoying the roots. Any advice on this would be a lifesaver.

only advice I could offer is either shorten your on cycle by 4-5 minutes or weaken the drip flow.

if the root system is small and dependant on the cube for water you must put your dripper away from the rockwool, never drip on it, i dont know if you use rings , a dripper or just plain tubing, if you let it run around the cube it will train the roots to go out an seek water, i only like RW as a starter, hate it as a medium cus it retains too much water and chokes your roots out of oxygen, so if the RW is constantly wet, the roots dont have a reason to go and search for water. your roots are scavengers and if you gave less waterings you will be making them suck the clay pellets dry and grow downward looking for water, i personaly had a crazy PH issues cus i ran too many drip cycles, i ran 15/45 and since i changed over to 8 times in a 24hr day, good luck

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Leave longet intervals between matering periods to let your cubes dry out more. If they're buried in hydroton it's not going to dry out as fast so you need to give it more time to do so. Maybe water for fifteen minutes every hour to hour and a half. If you're running 18/6 don't water during the dark periods. Good luck.

Thanks for the advice guys, much appreciated.

Yes, I do use rings (made them myself out of Tees and spaghetti tubing). I opted for the rings instead of the steak just for that very reason (So as not to soak the RW). The thing I quickly realized about hydroton is that water distributes through it pretty well. Point being, even though water is not being dripped on the rockwool, it's still getting wet (sopping wet actually).

Funny thing is, even though the rockwool is soaking wet, the roots have already made their way through the clay and out of the net pots and are dangling in the tray, and looking great BTW, all fuzzy and white (I have a coroplast cover over the tray so as not to let light in and keep the humidity high in the root zone). That and the fact that my water doesn't smell is why I ruled out root rot as the problem.

Well, last night, just after I posted my problem on this forum, I decided to shut off the pump entirely. I took a chance and decided to leave it off overnight to see for sure if it was an overwatering problem (I know, risky - I didn't sleep very well!). I figured if I did this and left it overnight and checked it in the morning, the plants would tell me what was up. Sure enough, when I (nervously) opened the door to the grow room this morning, they were all looking much perkier, not totally recovered, but definitely a significant improvement. So this pretty much confirms that its over watering. Only thing is now, I'm not sure what watering cycle I should go with. If the plants are still getting plenty of water almost 12 hours after the pump was shut off, what cycle should I use? I had to go to work, so just for safety's sake I set the timer for three 15 minute on cycles today, that's it. Only shitty thing is, the dangling roots down below (protruding our of the net pots) are air prunning a little, though I expected this, will this be a problem?

Anyway, I guess only time and trial and error will give me an final answer. I'm only dealing with rockwool now because I had to start a bunch of seeds. As soon as these plants mature and show their sex, I'm cloning the best female (or two) in a bubble cloner (So I don't need RW) and planting directly into hydroton. This should makes things much simpler next time around. In the meantime, I'll keep posting the results of my experimentation.

If anybody else has an opinion/advice I'd love to hear it. Otherwise, thanks again to the folks who responded to my plea for help.

from the pelletts holding onto some moisture you will find out they will lick those balls dry =) and make it thru the night, if on a 12/12 lighting schedule 4 drip cycles works great

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Damn weed roots are freaky eh

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rockwool doesn't need to be watered every hour, I would guess if you do 5 minutes every 3 hours you'll see better results. Just keep them from getting bone dry but don't keep the rw super wet, it tends to oversaturate.

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My last grow I started out with a drip setup and ran into the same problems your having. Started with the stakes, then made rings, and finally ended up going with flood and drain.
The rings I made were the same size as the inside diameter of the pots. This worked fine for several weeks, keeping the rock wool dry wile only feeding the roots. The problem with that setup was, the holes in the rings would start plugging up with salts making it necessary to constantly clean the tubing and rings.
Switching to the flood setup eliminated all my problems.
If you go that route, only flood your pots to a level that is at least a 1/2 inch below your cubes. the cubes will stay dry wile your only feeding the roots. You can flood as many times as you want since your using clay pellets. No worries of over watering. Way less maintenance this way.

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Thanks for the input.

hmm, this doesn't seem to be a problem for me, at least not thus far. Though I wouldn't know really because I have the drip rings buried in about a half inch of hydroton (to avoid algae problems), and to check them would be a real pain in the ass. All I know is there is water dripping from the bottom of the net pots when the pump turns on, so I can only assume that the rings aren't clogged.

I was considering this, as I've heard a lot of good things about the ease of use of a flood and drain setup, my only problem with that option is that I have a 4'x8' tray that is about 6" deep. So when I did the calculations, I figured I'd have to flood to about 4" deep at least. 1 cu. ft = ~7.5 gal., so 4x8x.4 = 12.8 cu.ft., therefore 12.8 x 7.5 = 96 gal. That's a whole hell of a lot of water to put in a reservoir, not to mention nutrients, etc. and then changing that out would be hellish. Right now I'm using a 20 gal. res which is a lot more convenient. Unfortunately, with the way I have this setup, I don't think flood and drain will be feasble. Unless I'm missing something, any suggestions?

Anyway, here's a shot of roots of one of the plants to give you an idea:

Attached Images

roots.jpg (133.0 KB, 268 views)