Backyard Aquaponics
A place to discuss aquaponics

Hi all,

I am setting up an aquaponic system in an earth-sheltered green house I am building in the next few weeks. I am struggling with a few of the design concepts. The second hand system I am looking at purchasing has two 2,000l tanks, and a few growbeds (4 to 6).

I have the following (probably painful and repeated) questions:

1. For a 1:1 ratio, do the calculations include just the total volume of the grow beds (or do you need to take away the volume of the media)?

2. Do I need a sump? I could use the second 2,000l tank as a sump, but wouldn't mind putting fish in it if I wanted to expand. Could I use a smaller tank as the sump (e.g. an IBC)?

3. I get the impression that systems using siphons are most popular, but they run a pump constantly. Does that use more electricity than a flood and drain system? I would prefer to build the most energy efficient system I can.

Ultimately I am unsure what would be the ideal design. We are doing quite a lot of earth moving when building the earth sheltered green house, so can bury the sump if necessary to have one.

Thanks in advance to anyone whom has the patience to answer my lengthy post....

Tamar

1. just the total volume of the gb -
2. if you are running 1 2000 gallon ft, and have a volume of 2000 gallons of gb, for each gb, you'll need 30 to 40% of the volume to fill it with water.. if your tank water level fluctuates too much, then you may need a sump..but if you can live with the fluctuation, it's fine not to have one.. adding a sump does add more water to the system, which helps with temp stability..
to size your sump, you need to know the volume of your growbeds (volume of water it takes to flood) and provide enough water so that your pump doesn't suck air..
3. if you have your pump on a timer, you need a bigger one to pump the required volume (turn over the volume of the ft at least 1x an hour).. if you have a small pump running all the time, it's low wattage.. a case can be made for either style

good luck, keep asking questions and take lots of pics to share with us!

Siphoned systems are Flood & Drain as well Tamar, just with fewer potential fail points. In a timed F&D system the pump needs to be 4x the size of that in a siphoned system... in addition to what Keith said in regards to pump sizes/power consumption maybe have a read of this recent thread: viewtopic.php?f=8&t=17271&p=401891&hilit=pump+power+timer#p401891

another option, in my opinion the most basic with less fail points, is constant flood with an overflow level, no siphons, no timer. if you want a 1:1 ratio, tank space to GB space, in your gb there is no need to differentiate between media and water volume. 1:1 is total volume to total volume.

With a proper media guard, siphons rarely fail.

If you build the system with a bell siphon... remove the bell and you have a constant flood system.

Put the bell back in and you have a flood and drain system... best of both worlds... and there are benefits to both systems.

I like this flexibility and use it myself.