All that as a background to this new portable system. Since I'll likely be giving workshops, I figured it would be good to have a system that I can bring to show the students. I didn't want to do something small in a fish tank, 'cause I don't think that really captures the magic of aquaponics. Plus, I wanted it to be big enough to be useful to me, since I'd be investing my time and money into building it! So, I thought about what I would need as far as supplies and finally got some time this weekend to put all the pieces together.
First, the materials:
* 110 gallon stock tank from Tractor Supply ($60)
* 630 GPH pump from 5th Season Gardening ($55)
* 3'X3' Botanicare Tray from Sunlight Supply ($100)
* 2 treated 2' X 4' piece of lumber from Lowe's ($8)
* 2 sawhorses (I had some sitting around, but they'll run you about $35 new)
* PVC fittings for the drain from Lowe's ($10)
* 3/4" garden hose from Lowe's ($30)
* shut-off valve for the hose from Lowe's ($2)
* 15 slotted pots from 5th Season Gardening ($15)
* large bag of hydroton from 5th Season Gardening ($35)
* 4' X 8' sheet of polystyrene sheathing from Lowe's ($10)
So, if you stop right there, you have my system, but it's not portable.
The portability comes in by also buying:
* 2 55-gallon (clean, used, with hose faucet at bottom and removable lids) from Baytec Containers ($100)
* 1 FishAlive KA 1100 aerator (not yet purchased, but should be about $65)
Portability is achieved because:
* I'll pump out half the water to each of the 55 gallon drums on my truck.
* I can scoop out the fish with a 5 gallon bucket and put them in one of the drums on the truck
* The aerator can keep them alive for many hours (6+) while driving
* The plants are in pots that I can take out, one by one
* That leaves just the parts to carry, which, when dry, are easy enough to lift
Here are the photos:
This is the system, all set up and running on my back deck. Having a nice, level spot is key. Grow bed on top with 15 pots filled with hydroton, fish tank under it, regular garden hose delivering water from pump in tank (can't see)
This is a 6" pot with hydroton. Planting in pots will make it easy to move the plants around and disassemble and reassemble the system in a different location
This is the bell valve cover, patterned after Affnan's design. I had to modify it slightly, because the Botanicare trays have channels for the water to run through. So, the teeth are different on mine than on his (and he definitely does a nicer job of making his look tidy and professional!)
If you pull off the bell valve cover, this is the drain. It's a 2" funnel design that goes into a 1" bulkhead fitting (see below). Without the bell valve design, water would flow in and then out this drain, but never go any lower than the top of the drain. With Affnan's siphon, though, almost all the water drains out, even while it is filling!
This is a look "under the hood". You can see the bell valve in place, the big teeth positioned in the channel while the little ones are on top. The tops of all the teeth are about level. I eye-balled it, so I'm sure it's not perfect.
This the bottom of the bulkhead fitting and then the drain into the fish tank. I ended up with a double elbow to minimize splashing and find the right balance to get the siphon to work properly.
I purposely bought a pump that was a bit oversized for my system, knowing that when I'm setting up and taking down my system remotely, it'll be nice to have a little more power, so I don't spend so much time standing around waiting for water to move from point A to point B. So, I needed a little flow control on the inlet to get the siphon to work properly.
I have to say that the hardest things about this were:
* Getting the siphon to work properly. I tried a lot of different combinations - altering the flow rate, altering the teeth, altering the length of the drain pipe under the grow tray, adding in elbows under the grow tray, and even trying to use a sponge to slow the inflow water down a bit. I wanted it to work at full throttle, because I figure it's going to be a little challenging to get the throttle exactly where it needs to be when I'm on the road. But, I couldn't get that to work properly, so I had to choke it down a bit. I plan on marking the exact alignment of the plastic throttle (above), so that I have a pretty good idea about where it goes. However, these siphons are finicky little creatures. Too little flow, and the siphon won't cut on. Too much, and it won't cut off. There is a VERY fine line between these, and you have to hit the sweet spot. Once I got everything leveled and had a good feel for what to do, I was able to find the sweet spot pretty easily, though. For more about this siphon, please see Affnan's blog. I highly recommend it. He goes into great detail about how everything works and has nice figures.
* Cutting the styofoam for the pots. It wasn't difficult, but it takes a long time and is messy. I probably should caulk around all the edges to keep little pieces of styrofoam from getting into the system. I ended up having the most success with a little pumpkin carving knife from a Halloween kit!
The above is probably the world's most boring movie, but it shows the siphon from when it starts draining all the way through until the siphon kicks off and the grow bed is almost completely drained. It's takes about 2 minutes for the tray to empty, and it takes about 10 minutes for it to fill to the point of starting the drain cycle. So, that means that every hour, my system will be draining and filling 5 times. By the way, you'll notice a slight drip/leak. That's 'cause I didn't use any caulk around the bulkhead fitting. Since I want it to be portable, I figured it would be best to take the whole drain apart for moving, so that the grow tray is easy to stack without having a drain sticking out of one end. Since it drips into the fish tank, I don't think it's a big deal.
Yesterday, when I was still trying to get the siphon to work properly, the siphon would work correctly for 2 - 3 cycles, and then it would start to auto-siphon. Today, it's gone for about 3 hours or so without a hitch. I'm hoping that means that it's good to go!
So, I'll let this thing spin by itself for a couple of days. I put about 10 gallons of my pond water in it to help kick start the microbes. I plan on putting about 10 goldfish in here of varying sizes. I want to use this system as a hatchery for tilapia, though. It should fit inside next to my south-facing sliding glass door, so I can keep it going through the winter without having to heat the water. I'm really looking forward to having my own stock of tilapia to use in my pond for the summers, since my supplier has yet to FAIL me! 3 summers in a row I've tried to get tilapia in my pond, and it hasn't happened yet...
Well, sorry for the long post, but I hope it was informative.