This is a translation of rataplan's topic on wietforum. The pictures are his aswell.
He started the topic after many questions about his way of growing, specifically what he grows in.
Instead of using pots, you can use big tubs wich you fill with soil and plants.
So instead of 1 plant per pot you get one big trench with multiple plants.
- You can re-use the soil for many consecutive grows, only the top layer has to be removed/changed.
- Easy watering.
- Less nutes need to be added, giving the composition of the soil is right.
- Since you have a big amount of soil, it acts like a better buffer against little mistakes (Ph, EC,watering,etc..)
- More space for roots means a bigger rootsystem and healthier plants.
- Perfect for seedlings.
- The more volume you have, the better the soil stays at ideal temperature at night, allowing you to save on heating equipment and such.
- You don't have to throw away countless bags of soil at the end of the run... znd don't have to buy and bring in countless more bags of soil to start your new grow.
- Watering is very reliable when you use a tensiometer (1 meter should be enough)
- After a certain time, if you want to take out some plants (ie. those lagging behind), it might be impossible due to root intergrowth
- Plants are harder to handle, you can't just pick one up to examine it under better light.
- If your tub is really big you might get some accessibility issues.
- If you make big mistake you ruin the whole medium.
Now, let's get to work: (pictures from rataplan)
Normally the norm is that a 400W HPS' effective coverage is 70x70cm, and a 600W HPS' 120x120.
During tests however it turned out that an area of 100x100 is still good for 400W while giving you more space and that for the 600W lamp you can go up to 130x130.
Rataplan used "osb plaat", wich comes in 244x58cm plates (thickness 18mm) but mdf, drywall,... anything with sturctural integrity works.
This is a tub for 2 x 600W lamps so you'll need:
- 2*244cm + 1*244cm board cut in half (2*122cm)
- 8 T-squares (with pre-drilled holes,size to your apreciation)
- 32 self-tapping wood screws ( that fit trough said holes)
- Pond liner, chose to your own appreciation, keep in mind you need about 10cm standing up on the sides to avoid water leakage. It doesn't have to cover the whole tub if you use a tarp, so 3x2m should be fine. 4x3 if you want to cover the whole tub in pond liner.
- Tarp, 4x3m to cover everything (not if you allready have a 4x3 liner)
- Drainage tubing(with plastic isolation to prevent clogging with soil) wich will be used fo watering, 2*5 meter disposed in a spiral should do.
- Hardware to fix tubes
- PU foam or other to plug the end of the tubes and fix them to the bottom of the tub.
Here the basic "tray" is allready put together with T-squares on the inside, 2 on each side (top & bottom). With an electric screwdriver and a friend to help you this will be done in no time.
Now the pond liner goes in. Cut it to size with a stanleyknife, use a piece of board or something similar and straight as a guide to get straight cuts.
Now put the pond line in the tub and spread it evenly
Staple it in place, and fold it over in the corners for strength
Do the same with the tarp, position it and staple it. Go all the way over the edge with this one.
Now we are going to put the drainage tube in.
Cut it to size and dispose it in an spiral fashion on the bottom, this will allow the water to be spread evenly.
Use weights to hold everything in place until you are satisfied with the results. Then use small amounts of PU foam to fix it. Don't forget to plug the end ("way-out" side) of the tube with some more PU foam ( wich expands a lot! so only use a little) or else your water will just come flowing out of the end of the tube. Also don't forget to keep the "way-in" side free so you can reach up to the edge with it later
Now bring the other end ("way-in" side) up to the edge of the tray and fix it there, this is where you'll be watering your plants from.
Use tape to cover/finish the seam of the tarp
The rest is finition&detailing. you can paint it, decorate it etc..
If you have all the materials you'll only need 2-3 hours to finish these tubs, and enjoy them for a long time.
Voila, I hope I didn't screw up too much, any additions and/or corrections are welcome!
(Unfortunately, the pics are off putfile, the thumbnails work but the actual pictures aren't there anymore)