Aquaponic Gardening

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Saturday I attended the Aquaponics workshop in Oceanside. It was Murray Hallam's first US workshop. It was a very informal event, and the 25 or so of us interrupted constantly with questions, comments, and shared experiences. Though as Murray said, AP is simple enough that there just isn't 8 hours of information for him to share anyway. So our questions helped fill in the time profitably. It was great to be able to ask specific questions about our own systems and get individualized answers and group discussion. He seemed much more interested in helping us all learn than in selling us anything, and in fact warned against people who wanted to make it all more complicated than it should be.

A system in action
Almost everyone in the room had clearly done their homework before getting there. But I may have been the only person other than our organizer (Richard) who actually had a system already set up. In the afternoon we went a few blocks away to Richard's house and got to see his sytem. It's a full-sized system based around one of Murray's kits:
He had about 50 tilapia, some fingerlings and some about mature, and his entire system (excluding an extra duckweed kiddie-pond) was housed in a framed greenhouse that I'd guess was about 8'x10'. Murray joined us there, which gave us great opportunity to ask questions that were raised by seeing an actual system.

One of my questions was about various auto-siphons. I've built a bell-siphon, and it's tempermental enough to worry me. I'm using a timer-based fill and drain right now, but it has its own risks. I asked Murray about using a U-siphon and he said that or a loop-siphon would work just fine. What a relief!

Richard was showing Murray his cucumber plant, and said it had set fruit but the fruits just never matured and Murray said he should hand-polinate. Luckily (for me) Richard didn't know how, so we got to watch Murray show us. Fascinating. You need to pluck a male flower, pull back the petals so the stamen is fully exposed, and rub it against the stamens of all female flowers. (How do you know if it's a male or female flower? Because the females have fruit setting below the blossom, and the males just have a skinny stem.) That only needs to be done if you don't have natural polinators taking care of it, but since it's in a greenhouse it's less likely to get the right flying visitors (even though Richard said he leaves the big door open all day).

Murray said that his fish didn't seem interested in the Black Soldier Fly larvae. On the other hand, he said at a different time that any time he changes food, the fish ignore it for a while as if they don't recognize it as food (except lettuce, which they always attack). So I wonder if the problem with the larvae was only that they didn't see it often enough. He purchased an organic food pellet from Indonesia. I, of course, would like to try to grow all the food myself. I'm hoping that a combination of duckweed and larvae, with the occasional lettuce, will be sufficient. And that I can grow/raise sufficient quantities of them all. Particularly since I want to feed some of the larvae to the chickens (along with fish scraps - head, bones, skin). So I'll need a good volume of all of that. And since the larvae need to be fed vegetation, I have to make sure I'm not putting all of my growing power into feeding the fish, grubs, and chickens. I want to grow some food for me also!

I got a chance to ask about feeding frequency, and he said he feeds the fish twice a day in the summer, but only once every 3 or 4 days in the winter. I'm glad I asked, because I would never have realized that. And overfeeding can be a serious mistake.

He suggested that for domestic systems, if we're going to do any rafts (or in my case, towers) that we run it off the sump water, since that is already as filtered of solids as possible. You do NOT want solids in your raft since they'll attach to the roots and kill the plants. In a growbed, that is handled by worms. I, of course, don't have worms in my mini-system. But I'm filtering solids to combat that problem. Though as he said, that removed some of the very valuable nutrients from the system unless I process the solids I'm filtering out.

I need to research more specifics on how to filter the solids, but he said basically that you put them in a bucket and bubble air through them for several days, and that releases the minerals. Whatever solids are left over you put into your compost heap. I need more information than that. I think perhaps you put them into water, and that the minerals are released into that water which you then strain off the top. But, again, I'm not sure.

Worms (he said) seem to show up on their own. He hypothesized that they came from seedlings he'd purchased from the nursery. But he said you can purchase composting worms (such as red wrigglers). He also suggested a worm feeding station: one of the heavily drilled baffles like the one around the siphon, set up in the corner of the growbed, and put kitchen veggie scraps in there (though not onion or garlic).

Gravel (3/4") is better than expanded clay if you can find gravel that isn't too high in pH. It provides better spacing for worms, waterflow, and roots. With the clay, you'll occasionally need to clean it out. With the gravel it should maintain good flow. Though he does periodically run a scraper along the bottom of the beds, under the gravel, to loosen things. I'm picturing a hoe or similar device.

He recommended the use of bird netting, but NOT mosquito netting, as the smaller insects are quite beneficial to a system. Some of your plants are going to be eaten. That's just the price of organic farming. Though healthier plants are less likely to be bothered than unhealthy ones. So health and companion planting are the best pest protection.

Jade Perch are much higher in Omega-3 than even atlantic salmon. I need to see if we can raise those in the US. Don't mix fish species in one tank, as all fish seem to be prejudiced little buggers. But if we *can* do jade perch here, I'd like to branch into that after we work the bugs out on the (more forgiving) tilapia.

Misters (in a non-humid area) will lower the temperature in a greenhouse by about 5 degrees C. That's about 9 degrees F. I think that's sufficient to handle the summer heat here if the greenhouse is ventilated and shaded.

I'm really leaning toward a CHOP (Constant Height, One Pump) system even though that means we won't be able to bury our tanks for insulation, as we had planned. Though if we're handling the heat with misters, we really only have to worry about the winter. And aquarium heaters are very inexpensive. So with the CHOP system, we'll have the fishtank overflow into the growbeds. The overflow will use a pipe to pull from the bottom of the fishtank, thereby grabbing the richest water. (Don't forget to vent the top of the overflow pipe so it doesn't form a siphon!) The growbeds will drain into the sump tank. (The sump tank needs to be big enough to hold the complete drain of all growbeds without overflowing.) The sump tank will pump back to the fishtank, forcing that to overflow and continue the cycle. (Alternatively, the sump can pump into a raft or tower system which will directly flow into the fishtank - this way the raft/tower is getting the water with the fewest solids.) Optionally, the sump tank can be fitted with a toilet-tank float valve to force automatic top up if the water level reaches a low point.

Murray cautioned that the hardest part of commercializing is finding your market. Without that, it won't matter how well your system works. I did some "field research" at my local farmer's market, and one of the booths was selling small, scrawny bunches of basil for $3 each. At that price, I could probably retire. Though I suspect that was too high and they probably didn't sell many. If I could grow them in towers, I'd like to actually take the towers to the market and sell the plants picked to order. I think the novelty would bring people to see, and that plus the freshness would be a great selling point.

If my local produce buying club is still around (and they seem very solid) I think that would be another great place to sell to. Both produce and fish, perhaps. Plus there is my e-volve ning group. Of course, making a profit will be secondary to supplying our own household needs. But if all goes well, I would like to use the excess at first to trade (whether through a direct barter, or by selling and using the funds) for proteins and produce we don't raise ourselves. In a perfect world, we could then raise enough more than that to actually provide an income.

As always, I'm ready to just jump in and do this. I'm not sure that the workshop changed that at all, except that it gave me some more reassurance that help is available when I run into trouble. And it clarified some of the directions I think I want to go... all subject to change as always when I start doing things or I get more information.

But I'm ready!

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