DWC Raft Construction Update #2

OK...so I have finished hooking all the components up for the new DWC rafts in system 2. All is working according to plan. The only adjustment I had to make was to the riser tube coming off the bottom of the FT's. I had to shorten it by 1" as I was having an overflow problem in one of the FT as the ebb/flow grow bed were draining. Easy fix, with a hacksaw and 2" coupling. I have also built a weather protective box for the pumps and air blower. I still need to paint it to match the greenhouse...shouldn't take more than a couple of hours to paint.

I have included a video overview of the system so far....

  I purchased 4  - 4' x 8' extruded polystyrene 1" foam sheets from Home Depot for use as my rafts. I then cut these into 4' sections and drilled 3" holes, using a hole saw, in each to accommodate 3" net cups.

 I have 5 rafts that each have 36 holes on 8" centers and I have 3 rafts that have 16 holes on 12" centers. This gives me a total of  228 holes for plants in both rafts combined.  The 8" center hole rafts will be used for leafy vegetables such as lettuce, Kale, Greens, and Herbs, while the 12" center rafts will house tomatoes, cucumbers, squash, peppers, cauliflower, and broccoli.   I had to paint the tops with a latex based paint to provide some protection from the UV rays of the sun.

All painted up and installed in the rafts.

I also drilled 1" holes about every 2' for air stones coming off the 1" PVC airline running down the middle of the rafts. As you can see from the photo, there are plenty of bubbles coming up against the rafts.

After completing all of this work, I noticed that the top layer of weed block was breaking fairly rapidly in the sun, so I decided to lay down UV resistant tarps over the weed block, hopefully I will get a couple of years use out the tarps before they need to be replaced.

 Ultimately, I will be placing pea gravel down over the weed block, but no time for that now...I'm off to get some Mozambique Tilapia at Overton Fish Farms....

Next up ....the Tilapia.

Greenhouse Re-design with Electrical and Water sources added.

OK...so the first go around on the greenhouse was pretty good, but after completing the structure and closing the door, with the door insert window open of course, the temperature soared to a whopping 135 degrees inside the greenhouse....not good for man or greens. So back to the drawing board, and after several hours of research I discovered that while I had approx 12 sqft of ventilation, I really needed at least 10 percent on the sides of the building and 15 percent at the ridge based on the square footage of the greenhouse which is approximately 240 square feet. While the 500 CFM solar attic fan took care of the ridge requirement  the three 4 sq ft windows in the side walls were not adequate for cross ventilation, so I was off to make some adjustments...major ones. I had to remove a total of 6 PVC panels on the south facing side of the building and turn them into windows as seen below. This provided another 24 sq ft of ventilation.

 

After further testing, this only reduced the temp in the greenhouse by about 10-15 degrees, still not enough, so the next step was to cut two openings in the north facing wall to allow for more airflow across the greenhouse. These openings were turned into shutters rather than windows for protection against northern winter winds and will be insulated as time permits, both openings were cut out to approximately 2ft x 4ft, for another 16 sq ft of ventilation. This dropped the inside temp to the ambient outside temp when all ventilation was opened. I also fitted barrel bolts to all openings in order to secure them when closed....here is a pic of the north side of the greenhouse.

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House screening was placed on all openings for pest control. Next I was off to run the electric to the building, this of course took me a couple of days to complete.I have 4 -110v 20A outlets, three inside the building and one outside the building as shown above and below.

A photo of the florescent light I installed.

I also had to dig an 8inch deep 60ft trench and place 12-2 UGF wiring to the building which took the longest...especially in the 100+ degree heat...whew!!! was it hot. Next came the water line, where I dug a 2ft deep trench 35ft to the house in order to tie into the backyard faucet. I placed 3 hose bibbs inside the the greenhouse for convenience with two being on stand pipes (see photo above) and the third being at ground level so I can drain the water out of the system when needed for repair or due to freezing temps in the winter.

Well, that's pretty much it for this post...now that the greenhouse is complete I can move on to the next phase building my aeroponics/aquaponics systems...more on that in the next post.