Click on the images for more details.
I went down to Wells Wed. night and talked to the harbor master.
The upwellers were home made and consisted of a plastic pipe about 15" in diameter. Big enough for a plastic bucket to go in. The water fed into the bottom through the side with 3/8" tubing. A shut off was at the entrance as well as at the manifold. There was no baffles or diffusers in the bottom. The chamber was about 6" to 8" from the bottom. I would estimate the water overflowing the top to be about 2 to 3 gal. a minute. There was also a drain valve at the bottom and some stainless steel holders.
Most of the trays were made from the bottom of buckets. A piece of fiberglass window screen was stretched across and held in place with a section of inner tube. Four holes were cut in the bucket bottoms to form an X to support the screen.
The first trays they made they used a piece of 2 x 4 ceiling light grid to hold the screen in place and then 1/8" wire rod for the support. He said that the rods had to be replaced often but the plastic buckets lasted.
Once a week they would take the trays out and was the algae off the clams and clean the upwellers. They had 20 trays for 75,000 clams.
They bought 75,000 clams from Beals 2 - 3 weeks ago. They paid $2700 for 75,000. They were 3 - 5 mm in size and they plan to release them at the end of August. They should be about 14 mm by then.
The plumbing was a manifold made with 1" pipe and "T"'s It was reduced to 3/8" pipe and had ball valves to to control the flow. The tubing was 3/8". The over flow merely went onto the floor and out the floor drain. The pump was putting out about 10 times what they were using and the extra was also going directly into the drain.
The plumbing was fed by a pretty good size pump. Theirs looked to be about a 1 1/2 hp.
The biggest expense would be the pump and the 15" pipe for the chamber. He said to stay away from anything except stainless and from what I saw most of it was plastic. I didn't think to ask if the chamber needed to be clear or if it could be made with a piece of plastic water main or sewer line.