DIY Hydroponic Raft System
There are lots of methods to grow plants hydroponically. Below’s a system that’s basic, low-cost ($20-$30 total) and “complicated” enough to please any first timer’s hunger for a fun task that really works pretty well. It’s called the “Raft System.” In concept, the raft system does exactly as it says. Plants are grown in Styrofoam “rafts” that float in a shallow pool of nutrient. To keep the nutrient from stagnating, a air pump is used to provide oxygen to the solution and the eagerly awaiting roots.
(1) 14 Gallon tub for a reservoir
(1) Single outlet air pump (Elite 801)
(1) 2’ x 2’ x 1.5” rigid foam sheet
(9) 2” net cups
(1) 6’ x 1/4” air tubing
(1) Air stone
(1) Small bag of LECA
(9) Seed starting/rooting plugs
(1) 1/4” compression grommet
+ Hydroponic nutrients
Electric or battery powered drill
3/8” or 1/2” chuck 1 7/8” hole saws for cutting plant sites
3/8”drill bit for drilling grommet hole
Jigsaw or coping saw for cutting foam
Razor knife for cutting tubing
A pen or marker
Step 1: Trace the outline of your container onto the styrofoam sheet.
Step 2: Measure the distance between the outer edge of your container and the inner wall (measurement ‘X’).
Step 3: Make sure to cut the styrofoam smaller sized than your outline so that it fits nicely inside the container. After a little bit of extra cutting, you must have a good fitting “raft” as revealed on the left. Make certain the styrofoam raft can move freely up and down inside the reservoir when it is loaded with water considering that the stress may deform it a bit. If this is the case, merely cut away till you can get 4-8″ of up and down motion. This is essential for this system to work correctly.
Step 4: Layout the plant sites on your styrofoam raft and utilize a hole saw to cut them out. You could make use of an utility knife to carry out the task albeit more challenging if you don’t have access to a hole saw!
Step 5: Mark off the lowest point your raft will reach inside the container (due to the wall taper or internal obstruction) so that you’ll know when to top it off in order to prevent the nutrient level from dropping away from the bottom of the raft and leaving your plants high and dry.
Step 6: Drill a 3/8″ opening in the bottom wall of your container and place the 1/4″ rubber compression grommet. Pass your air tubing with the grommet and connected to your air stone. REMEMBER! You need to mount your air pump above the max water level in your container to avoid back circulation of nutrient solution with the air tubes and into the pump.
Step 7: Time to plant your favorite seeds! I used scissors to trim the bottoms off the net pots since they were just a bit too long for the little 2” cups I used here.
Use clay pebbles to back fill around the seeded plugs and place them into each of the grow sites in your raft.
Step 8: Fill ‘er up! Add water, nutrients and plug in your pump: your raft garden will start gurgling and your plants will grow in no time – don’t forget to give them plenty of light and top off the nutrient solution every time it drops 2-4” or so. It’s also a good idea to completely flush and clean your raft system every other harvest using a 10% bleach solution and scrub brush.
Temperature: Cannabis prefers cooler temperatures. It bolts rapidly if things get too hot, especially if temps exceed 80 to 85°F (27 to 29°C). Ideal temps for most commonly grown varieties: 70 to 80°F (18 – 21°C) during the day and60 to 65°F (13 to 16°C) at night. Higher temperatures can also cause burning on the leaf tips.
Nutrient Solution EC from 1.2 to 1.4
Lighting: More light the better!. Lights should be switched on for 18 hours per day for veg growth. And 12/12 for flower development
And here is a nice use of this type of system to help you root some of your cuttings