Algae on rockwool??
 

Hi all. I'm getting my roots wet in hydroponics with a single DWC tomato in a bucket. It's about 11 days since I put it in the bucket and the other day I noticed what I believe is algae on the exposed rockwool. Two pictures here, first one shows complete plant, second one zoomed in to rockwool. The top of the rockwool has turned a bright, almost florescent green color. You can see a small spot on the right that was covered by a piece of the grow medium that's still the original grayish color of the rockwool.

Is this bad or harmfull to my plant? Should i cover the rockwool completely with the grow medium or just not worry about it?

Also, I'm using a 6" basket lid. Will this be large enough for a tomato plant? If I decide to continue further into hydroponics, should I get an 8" or even 10" basket lid for tomatoes?

Thank you. Looking forward to learning and growing here...

I don't see any on the rocks so I'm guessing you have the rockwool exposed to the sun as it is in the picture, right? If yes, that's the reason why it looks like it does. You need to take the tomato plant out from that rockwool and put the plant in a new 1. Then make sure you plant it deeper and cover the rockwool totally so it doesn't get hit by the sun.

Yeah, the rocks are clean and the rockwool is exposed to the light. It's also sitting down in the water by about 1/8 inch or so. The root was barely extending out the bottom, so I figured it's be OK to do for the first batch of solution then lower the level when I change it the first time.

How would I transplant it to a new cube without damaging it? It's only six inches or so tall, and I'm sure still fragile as all get out. The new rockwool, I can cut a slit into to insert it, but how would I get it out of the current cube? Is it still young enough to only have one root shoot?

As for it being exposed to the sun, this is an indoor grow. After reading a few other posts here, it seems I may not be able to do that with tomatoes. I'm not sure I want to spend the money on an HPS lighting system and ventilation to cool it, so if it's not too late in the season (which I'm afraid it just may be) I may move this setup outside and build something for lettuce and kale inside. The indoor tomatoes were just an idea for year-round fresh tomatoes. Maybe that's not something that's cost effective for only a few plants.

If that's an indoor plant what light are you using? You will still need to cover up the rockwool so it doesn't get any light at all or you will have the same problem.

First try cutting off the top portion of the rockwool if you can get enough off and it has no algae you would be good with that. If you can't get the algae off then you will have to slit the rockwool in the middle and get the plant out. You might lose a root or 2 but as long as you have a root or 2 still on the plant it can survive.

It's a duel bulb 'H' fluorescent fixture. Each bulb puts out 6500k at around 3400 lumen, so 6400 lumien total output. I got it because it's compact and I thought would be perfect for a single bucket, but I'm kind of regretting that now. Looking around, the bulbs are hard to find and more expensive than T5 or T8s. Live and learn, I guess.

Just in looking the algae seems to go down a quarter to half an inch or so. I'll try spiting it open and getting the little guy into a new rockwool today. It's too late to move it outside and expect it to produce, so may just keep it going inside and see what happens.

Thanks for replying Stan. If I decide to keep it going, I may start a thread in the blog or setup forum and keep y'all updated.

the algae is just an aesthetic problem really. if you dont like it, just bury the rockwool under enough of the other substrate to cut the light off of it, or just enough so you dont see it, the buried stem will send out roots, which is actually really good for tomato plants, and you can even pinch the stem before you bury it enough to just hear it crunch, that will strengthen the stem, but make sure it still stands up or else it will lignify into a bent position.

id go ahead and stick it outside too, youll get a ton more light, and they dont mind being in the water a lot more deep than what you have, just as long as you have good aeration to the water, aka an airpump with a hefty airstone in that bucket.

Thanks eronjohnson. I thought it might be harmless but wasn't quite sure. Drip systems seem to be pretty popular and I'm sure they get plenty of algae on the exposed substrate.

As for sticking it outside, this is an experiment to see if I can have fresh tomatoes during the winter. I want to make a go with it inside under lights. As you can see, it's doing quite well under the current ~6400 lumens right now. I'm planning on getting two two tube T8 shop fixtures within the next week or so and placing them vertically on either side. This will add an additional 11,000 lumens and distribute it more evenly over the whole plant. The whole mess comes to around $45.00 plus tax at Home Depot. Like I said before, I'm not happy with the price and availability of bulbs for this specialty fixture I bought. I want to replace it anyway, so may as well start now, and almost doubling the lumens at less than half the cost, I can't not do it.

I just use some craft foam and cut out a circle large enough to cover the square and cut into the center and make a smaller circle to go around the stem. Then mist with some hydroperoxide to kill the algae. Craft foam is really cheap and comes in lots of colors. Usually 4 for $1 at a craft store like Michaels.

Hello, I have just started with hydroponics as well. Also I have just started to see algae on my rockwool cube as well. I don't think algae is bad for the plants, but I think the algae is going to eat your nutrient solution.