Backyard Aquaponics
A place to discuss aquaponics

Hello enthusiasts

Our fish density is usually slightly higher than 1 pound per gallon. (Sorry, I grew up in the US and think in Imperial; blame the Brits who foisted it on us). We have several blowers on a manifold (see pic) so that my backup blowers are already installed and all I have to do if one craps out is to turn on another. At the current farm operation level, we have two blowers on all the time, so if one quits, at least one is still going. If the power goes off, a battery-powered bell outside my bedroom at the house rings and I know to go check and see if the autoswitch did its job and started the 7kW electric-start backup generator. If it didn't, I hand start the generator. If the generator craps out, I have a backup 2Kw generator I can jumpwire into the system in about 3 minutes. And my fish don't start gasping for about 1 hour after the air is turned off. I think they will start dying about three hours after the air goes off, but haven't tested that for obvious reasons.

Worst case scenario is the air goes off, we are at the beach, and I come back to 80% dead fish. These systems run on VERY low nutrient levels just fine, (ask me about that if you want), so my vegetables are all fine, and I have a load of fish to put in the cooler and sell for some cash flow. Just don't have much fish to sell for a while after that. Any other questions? It's fun playing in this sandbox!!

I just found out I don't have a blower installation picture on the Web anywhere, if someone's interested, email me off one of the website emails and I will send a pic to you.

If one blower turns off, wont most of the air from the other blower return to atmosphere via the one turned off? Or is there a check valve?

Can you also clarify your growout capacity for me... do you have 1 x 2700 gall tank or 3 x 2700 gall tanks?

Tropic Bird,
Somewhere in your stuff I believe you mentioned finding alternative sources for materials (because everything in the islands is $$$.) What materials are you using for your raft troughs? I gathered that the rafts are 2" thick blue board.

Aloha Friends,

We have four blowers (2 Sweetwater S-31's and 2-S-41's) on a common 3" PVC manifold. All have check valves on them. At the far end of the manifold is a 4" stub-out for the wind-powered blower we have designed and are building now. Wind-powered machine has a 3-bladed 18-foot diameter prop and design output is equivalent to about 10 kW worth of electrically-powered blowers at 12 knots wind speed after which output is constant to 30 knots. (I used to design and build electric wind turbines, a couple of lifetimes ago). When we have it online it will allow us to do a lot more aquaculture and ponics because one of our biggest costs is electricity now. Farm runs about $1,000/month electricity with blowers, pumps, ice machine and fridges for produce cooling. The blowers are about 70% of the farms electrical usage, so they were the obvious pinch point to attack in an alternate energy strategy.

Our growout capacity is 3- 2,700 gallon tanks, two 3,000 gallon breeding tanks with only 50 fish each, one 2,000 gallon growout tank, and a 1,500 gallon tank in our smallest family system with eight 4' by 8' rafts. I think we have a total of 4,000 lbs of fish in all systems together now. I'll ask them to get on the bathroom scales and report back, though, to confirm that figure. We also use our sump tanks to hold fish for growout; why not use the real estate was our idea. We went to much larger sump tanks than the UVI systems we learned on and are using 1,000 gallon sumps now with about 300 lbs of fish in the tank.

After going through two generations of trough design our current troughs are built with a single 2x4 top rail on each side, bolted to a 3/4" steel form stake going about 18" into the ground; with a piece of 1/4" exterior plywood fastened on the inside of the 2x4. The liner is 12' wide, cut in half, and stapled to the top of the 2x4, then gun-nailed down through a 1-1/2" strip of 1/2" plywood into the 2x4. The top of the 2x4 is 12" off finished ground, and the inside of the 2x4's are 54" apart. This spacing uses the 6' wide piece of liner perfectly. We figure the UVI troughs cost us $48/lineal foot including labor, our second generations troughs cost $22, and this version costs $11/lineal foot, including labor. We are using 2" thick 4' by 8' Dow blue board rafts. The 1-1/2" rafts UVI uses are a little cheaper, but are they ever flimsy! We think the 2" will last a lot longer.

Thanks for the detailed response ... it is indeed nice to meet people, who although operating a "commercial" venture, are prepared to freely offer information about their operations....

Kudos... it will/does further the application of aquaponics as an idea "who's time has come"...

Perhaps you may be interested in these people who have similar aims and aspirations as yourselves ... http://www.hoperwanda.org/hope/pages/default.asp?pid=32