After finally getting the finish coat of mortar on the inside of the grow bed, things are starting to come together very quickly for the (far too) long-term aquaponics project. The finish coat was more work than I expected, at first, as the scratch coat would quickly absorb the moisture out of the wet mud and render it unworkable. I started to pre-wet the dried scratch coat first with a spray bottle, and then things went much smoother (literally! I had pre-drilled the drain hole before mudding, just big enough to accept the 3/4″ fem. coupler and then left the coupler in place loosely while mudding, to keep the hole open and to maintain a properly shaped hole that would fit the coupler when it was time to glue it in. After the mud dried, I coated the coupler with Gorilla Glue (probably a marine glue or silicone would be better, but Gorilla Glue was what I had on hand).
3/4" PVC coupler with female threads as drain, screen standing by...
Once the glue had set up, I was ready to screw in the drain screen (sold as intake screens locally, for rain catchment systems). I knew I wanted to keep the media (1/2″ to 2″ cinder, in my case, scavenged from the neighbor who spread their yard with it a little too liberally and crossed our lot line- thanks neighbor!) away from the drain so that there is a space to reach my hand into to clear the screen, without having to dig out a bunch of cinder. A sump, essentially, and while I was planning on fabricating a cylinder of wire mesh, it turned out that one part of one of the piles of junk I habitually keep around- a 98 cent plastic pot. Just as well, I’ve had little luck getting shit to grow in it with soil. So- I cut a hole in the bottom, just big enough for the threads of the screen to go through, so that the screen itself would act as a lock-nut, holding the whole thing down snug to the PVC drain. Lovely.
Cheap plastic greenhouse pot is a perfect drain sump to keep cinder out of drain.
Bacterium's eye view of sump with drain screen visible through seep hole.
After connecting 1″ pipe to the pump inflow from the pond (another intake screen on the end in the pond) and gluing up the 3/4″ drain down to a 3/8″ hose barb, it was time to do a test fill. The pump is a 3/4″ Grundfos household water pump, that a friend had given me. It came on instantly to fill the bed as soon as I wired it up, but since then, I can’t get it to come on again. I think it is because it has a water flow sensor and is only supposed to kick on when it senses that water is moving through the pipe (like when you open a tap), but that’s not really going to work for my needs, as I need it to come on when a timer tells it to. I suspect I will have to go inside of it to jump the sensor circuit.
If you hear three knocks, let me out.
Oh- at any rate, the bed filled up with water in a few minutes (13 gpm for the pump) and it didn’t leak at all, and I did a little stomping happy dance. Only for a few seconds though, as I noticed the ducks were watching me with very funny looks on their faces.
Grow bed filling with water as test- no leaks. Pond is to the right in this view.
The fish fountain you see in the pic below moved here with us from Albuquerque years ago. He’s very happy to finally have a purpose. The 3/4″ drain drops from the bed to the ground level, then a 3/8″ i.d. hose is connected to it and runs about 10 ft into the pond to the fish fountain. The hose restricts the drain enough to make it take nearly an hour to drain out, while providing a nice little 12″ spout of water from the fountain. That’s the key to the flood and drain type system- every three hours, the timer will kick the pump on and flood the grow bed with pond water laden with nitrites from the fish poo, which bacteria that live in the cinder, convert to nitrates, which the plants love to gobble up, and then as the water slowly drains back into the pond, it is cleaned and oxygenated.
It’s all just lovely to think about.
The pond- ferrocement lined, and a koi fountain with 3/8" i.d. line attached as the drain for the grow bed. And a duck.
I suppose now I have to get some fish.
Tags: aquaponics, Garden, Sustainability
tweaks and getting things right.
