Backyard Aquaponics
A place to discuss aquaponics

Hello all- I have been reading about Aquaponics for awhile and have decided to give it a go.

It seems to me one of the biggest concerns is keeping the system active in the winter (at least in the cold midwest), so I designed around that factor.

I would like to build a greenhouse that is dug out of a hill side, using two terraces within. I hope to using the earth as a thermal storage battery for temperature regulation (along with venting, et al).

Anyway, I was wondering if anyone has any constructive comments on this design (I have attach a drawing)

here are some of my questions-

- Would this work as a flood and drain system?
- Will this allow for single pump with gravity flow?
- will auto siphon work in this scenario?
- Would sump tank need to be 500 gal.

Will your pump be in your fish tank or sump?

Will there be 2000gal fish tanks total?

Sorry I can't tell for sure from the diagram.

The system would be four 500 gallon fish tanks, gravity feeding into 160 square feet of grow beds, with a floating raft onto of the sump tank. (plus vertical towers if the nutrients allow/demand.)

If I am understanding right when the siphon on the first set of beds is triggered it would empty into the second fish tank and overflow into the second grow beds (very quickly). The second GBs would fill and then sit flooded till the first GBs drained again (could take a while). It would then trigger the siphon on the second GBs and that would drain until both the first GBs and the second GBs was empty. The second GBs would then sit empty till the first GBs drained again.

I think this design could work but I don't think you would end up with enough control of your flood and drain cycles on the second beds. They would always be flooded twice as long and dry twice as long.

I am sure there is some tricky things you could do to make it work better... but usually try to subscribe to the "keep it simple" method.

If I could make a suggestion I would locate the grow beds on the highest plateau. I would then pump from the sump to feed the beds. The beds would then siphon into the four fish tanks individually and the fish tanks would overflow individually into the sump. This could be ran with one pump.

Man, I am sure I messed that up somewhere but oh well it late.

Hope this is helpful

Sorry one more thing, your sump needs to be a minimum of 500 gal. I would think more like 600-700 if you can just so you can have a little water at the bottom. Don't want to run dry...

For sump sizing just figure the maximum amount of water that could drain to the sump if the power went out. Usually I figure about 40% of the total volume in a growbed is water filling the spaces between the rocks. You also need to figure in the pipes that will drain anything from the fish tanks. The estimate will likely be slightly higher than will actually drain but I'd add even more capacity to the sump so you don't have to add water because of evaporation all the time.

Making the DWC your sump means that the water level in the DWC will be fluctuating all the time?

Aboman- If the fish tanks had float valves, would that kind of isolate the actions of tank/bed 1, from tank/bed 2?

Also, since the single pump would be flooding both the west and east sides simultaneously, I would need a 1000(1200) gal. tank for the sump?

Scotty- yes, although I'm sure that is less than ideal for the DWC, I thought I'd try to stack the functions of the sump tank, and I saw someone else on here doing that. Its either that, or a lap pool

I don't think so. Your fish tanks will always be at a constant height. The only way I can think of at the moment would be if FT2 overflow was undersized to allow for a constant flow into GB2. This would mean that the overflow for FT2 would need to be lower in the tank or the tank would need to be taller.

I still would not recommend it as this amt of water in amt of water out would be a delicate balance. Also, without careful calculation/experimentation you could end up in a situation where you need more or less water in GB2 when adjusting your siphon. You may or may not be able to make the adjustments you need...

As for the sump. Scotty's correct.
Your total GB space 160sqft X 12" deep = 160ft cubed.
There are 7.48gal in a cubic ft so 160 X 7.48 = 1196.8 gal
Your media will take up a little over 50% of that so 1196.8 X .45 = 538.56gal
You wont be filling the top 2" of your bed so we can drop 1/6 of this total so 538.56 X .16 = 448.8gal

In the event that all of your GBs emptied into you sump at once you would need 449gal capacity. However, as Scotty said you will need to oversize it to deal with plumbing water and other small variables + you will have a pump in there so you want to make sure it does not run dry.

If your doing the DWC in the sump I would oversize the sump such that the water level never gets lower than 12" or so. I think this would help make the DWC work better ever with the fluctuating levels...

I noticed the question of auto siphons, yes it can be done, and here is how. Only use the siphons in the top beds. In the lower beds use a standpipe with a small hole at the bottom ala timed flood and drain. So what will happen is the pump will pump to the fishtank. The fishtank will flow into the first set of growbeds. They will slowly fill, then quickly drain into the lower beds. Those beds will fill quickly, then slowly drain into the sump. If the siphon triggers early, while there is still water high up in the lower grow beds, the standpipes will prevent overflow, and the water will just drain faster into the sump until the siphon above it stops, then it will continue to slowly drain.

Eureka! +1 Ron. That's an even better idea.

Not having tried what Ron suggested, I can't be certain but it sounds like the drain standpipe in the second growbed should be pretty good sized so that it can handle the overflow from the siphon quickly and without backing up.

Yeah, I think I would also oversize the smaller drain and then put a adjustable valve on it to allow you to dial in drain rate. Although this would mean instead of a weep hole you would have a separate smaller drain from your standpipe...

Whatever you do don't take Ron's suggestion seriously, he is a pirate after all! D

Careful Martin! I can keelhaul you!

Perfect Ron- that is how I envisioned it! A constant tripping down the line. I wife will appreciate the waterfall effect too.

I am hoping the dug out greenhouse will mitigate our harsh iowa winters to some degree (and the hot Iowa summers too)