hydroponics - kinda sorta

I'm experimenting with growing lettuce under lights in a float system. Basically it is a styrofoam (sp?) tray with 2"x2" cells. There is soil but the tray floats on water that has had a little miracle grow added. It is week three and so far so good.
If you are interested you can follow the progress here. http://www.kerrysgarden.us/?p=50


I have a couple of questions. Would it be possible to use something like rockwool? or another fibrous material that would wick the water up but allow more O2 around the roots? (The roots do grow down into the water also.) I have been meaning to add an aquarium pump to up the O2 in the water but as of yet haven't. Would circulating the water help keep the mosquitos out of it? Does a hydroponic system have to have the water circulating through it or can it be a standing in water situation like I am working with?

Any ideas or suggestions?

This message was edited Jul 18, 2005 11:16 AM

i would do something with the water , stagnet water isnt a good thing.
add a water pump to circulate the water. you could add a overflow
drain to the container and let the water splash back into the resivoire.
the splashing will bring up the O2 levels in the water. You could still
add a air pump and stone in there also.

rockwool sitting in water isnt good, since the little spaces are filled with
water all the time, unless your doing a fill and drain sequence you get no
O2 in the cube.

I would just use perlite as a plant support in them flats or growrocks.
you could even start the seeds right in the perlite or rocks.

Vb,
Thanks for the input. I will definately get the water moving. As for the rockwool in water. I was thinking of putting it in the styrofoam tray. The individual cells are an inverted pyramid shape with only the lower 1/2" or less in the water. So only the lowest part of the rockwook would be in the water if I put it in the tray (assuming I could even do that. I've never even seen rockwool). What I am wondering is if the rw would wick up the water enough to make it available to the roots and yet retain enough airspace to provide the O2 also.

Wouldn't starting lettuce seed in perlite be next to impossible? The seeds are so small I would think they would either fall down between the spaces and be too far down to get up to the light or they would stay too dry. I could be way off base but that seems like it wouldn't work with the setup I am trying to use. I suppose I could start the seeds and then transplant them into the perlite once they were up?

Rockwool is spun lava rock ( fiberglass insulation ) and it does have
a wicking action to it.

try this, take some damp perlite and fill in one of the cells
using something that will fit in the cell pack it down some
then you can lay the seed / 's and then add some more
perlite to fill the cell back up.

I'll check some of my links on hydro growing and get back to you.

Also you might want to get the book "Hydroponic Food Production"
by Reese , its a pricey book , but lots of good information in it.
it dont really show you how to build system but talks about a few.

I wrote a program for mixing Hydro nutrients, ( windows Program )
it all set up if you use the General Hydroponics Flora series nutrients or
you will have to do some measuring and testing to add any other
nutrients to the program.

look at the help section on the program for a overview and how to
add others to it will give you a idea what the program does or just ask
if you get lost.

http://www.angelfire.com/oz/growbase/NutrientPPMCalc/

Vb thanks for the tips and the heads up on your program. I've downloaded it and will try to look at it when I get back home later. Maybe the library has the book you mentioned. I'll look into it.

I harvested some lettuce today. Not a lot but enough for two good size salads for dinner. I just took the larger leaves, left the plants to keep growing and lowered the lights back down a couple of inches over them.

Not sure this is worth it $$ wise but I am having fun with it anyway. As I have it figured 12hrs a day of 160 watts (4 40 watt bulbs) is about 2kw hrs per day. I think we pay about 6 cents per kwhr so that would be about 12 cents per day. This stuff has been growing for almost 4 weeks so that would be 28 days x .12 or $3.36 plus the price of the seed. Next time I will seed all 72 cells (I just have 48 seeded now) so I should get more for the same amt of input.

Looks like you can use the rockwool and the wicking action wont affect the
plants. here is a link for ya ..
http://www.cornellcea.com/Research_Archive/Research_archive_commercial.htm

How cool is that? Oh to have a greenhouse. I actually built a vacuum seeder kind of like what they have for the lettuce. We were planting 80 200 cell trays with pelleted tobacco seed. With the seeder we could plant several trays a minute vs minutes per tray without it.