Over the last few weekends I have been stepping up my system to handle a few more growbeds. First, I had to increase my nutrient level. That prompted a bio-filter. The first version used bio-balls in a kitty litter tub which was mounted in the small sump where the water returns were. The new one is a 5 gallon bucket fed only by the fish tank -> solids filter -> Bio-filter -> sump reserve.
Second, increase the size of the sump reserve. My sump went from a 25 gallon tub to a sunken 105 gallon chain of three 35 gallon barrels. I also had to upgrade a pump with a weak lift to one that could handle at least 6' of lift and feed multiple growbeds.
Lastly, add the new growbeds. A single 35 gallon barrel cut long ways into 2 halves set in a raised table above the sunken barrels. I ordered expanded clay pebbles from Home Depot for these beds. I got a pretty good deal which include free home delivery... since they don't sell this stuff at the stores anyways.
The Barrel Table GrowbedThis weekend was spent building the table, mounting the barrels, supporting them, plumbing and then adding the clay pebble media. I read up on barrel-ponics setups and decided on a frame table with half-barrels and plumbed so that the water is fed from the bottom with an overflow in each half-barrel. When the water timer cuts off, the remaining water flows back through the inlet.
The top of the table is a simple 8 shape. An outer shell with a middle support between the barrels. I had to file down the top ring of the barrels to keep the frame square and the sides of the barrels close to the frame for mounting points.
Many thanks to my dad for helping with the legs of the table. We took 2 landscape timbers, cut 4 legs to length and notched the tops so that the weight of the frame would rest on the top of the legs. Bob Vila wouldn't be proud... but I think we'd get points for the effort because the table was level on the first try.
The barrels were a snug fit and mounted with 12 stainless steel screws and washers.
I put the table over the sunken barrels and used 4 7" square pavers to keep the legs off of the ground. It took a little digging to level everything on the pavers. Easy enough. I added a 2x4 under the ends of the barrels for extra support.
Plumbing is all 3/4"Tying into the timed pump feed was easy enough. I used 4 3/4" Uni-Seal gaskets in the bottoms of the barrels (2 each). A PVC T replaced the 90 deg at the pump (1 line for the existing growbed and the 2nd for the new beds) and another T to split between the barrels. I added a valve on each section of the line to restrict the flow. The overflow is a larger diameter pipe that is slotted at the height that I want the water height to stop at. The drains are water heater flex hose and feed the return water the sunken barrel that is farthest from the pumps. This helps with water circulation.
The explanded clay pellets that I use for media is NOT Hydroton. It is ViaStone and costs about half as much for the same product. I cleaned the first bag and put it in the barrels. Since it floats for a few days, I am added a little each day until the media stops floating.
