Design Idea- Will it work?

[James]

My daughter and I have been trying to plan out our aquaponics system. Here are the guiding principles that we wanted to accomplish if possible.

• IBC tote for FT
• Want a 2:1 grow bed if possible
• One pump if possible
• Trying to minimize fluxation of water in FT
• FT ideally lower than the grow bed

So the design idea is that the sump has a siphon that pulls water from the sump tank into the fish tank. I’m sure this would work if the siphon were a pump instead but we were thought that perhaps it could be avoided. We tossed around the idea of having a flap at the top of the siphon so that as water builds up it can let air escape but as the siphon starts to pull it would seal the flap and pull the water into the FT. We are most uncertain about the design of the siphon. It could be closed off entirely and ideally it would be hose not PVC as illustrated to aid the flow of the water.

We also that that the sump tank could possible be used to hold some smaller fingerlings or perhaps crawfish.

Let me know what you think. We are still in the design stage and would love to hear your comments or recommendations.

[TCLynx]

If you want a one pump operation and will have a sump and don't want the fish tank level to fluctuate.  I would recommend a CHOP or CHIFT PIST system.

A water bridge type siphon that I think you are trying to explain is prone to failure, You would probably be better off connecting the two tanks near the bottom rather than trying to siphon water from one to the other.

Keep in mind that if you go adding creatures into the sump tank, you then mess up your "2:1" ratio and you can't use as much of the depth of the sump tank to cover the fluctuations.

[Rick Stillwagon]

Put your pump in the sump tank. Have the beds drain into the fish thank. The fish tank overflows into the sump tank. The fish tank remains a constant level and the sump tank is your fluctuating tank. The sump has to have a greater water volume capacity than the beds after displacement by the media so the sump is not pumped dry before the bed drains into the fish tank (ebb and flow.) 

If it is a constant flow, raft or trough etc., then once the system is full there is no fluctuation in the sump. Water is self-leveling so water will naturally overflow into the sump from the fish tank as it comes back from the troughs.

[James]

Thanks for the replies. We are going to rethink the design and post again.  We do have a couple of thoughts/questions.

• About what percent of the water volume is generally required to fill up a grow bed so we can estimate the size of the ST we would need? We were hoping for a 2:1 ratio of GB to FT at a depth of 12 inches of media. I know it likely depends on the media but is there a general range that might help us for planning?
• TCLynx, what aspect of the bridge siphon is most prone to failure?
• Rick, based on your design idea would want your pipe in the FT to pull waste from the bottom of the tank?
• We were looking to use a bell siphon design in the grow beds because we felt it would be better with a larger grow bed ratio. Any thoughts on this? 

[TCLynx]

If you want a 2:1 Grow bed to fish tank ratio.  Make the sump tank the same size as your fish tank (if you are going to flood all grow beds at once or use siphons.)  The general rule of thumb is that it usually takes about 40% (once the bed is filled with media) of the grow bed volume to flood it and you want to have some extra capacity in the sump to handle the depth of the pump and so you don't have to top up every single day.

 

Bridge siphons or "No Holes Overflows" can get gas if a bubble builds up in the top of them, eventually it will stop the flow through the bridge.  Now you can minimize the chance of the air stone getting under the ends of the bridge by putting a couple elbows under each end to help keep water trapped in the siphon and reduce the amount of air that can manage to get up into the top but they need regular re-priming to remove any gases that manage to build up in the top of them.

 

And Look up SLO drains which is how you want to get solids out of the bottom of your fish tank without risk of draining the fish tank.

Here is a diagram that might help you out.

[Rick Stillwagon]

TC covered it pretty well in her diagram.  I question the return of the water to the sump though.  I see water being pumped from the sump to the fish tank, but it would seem simpler to just drain into the FT and have it overflow into the sump. I would ask her about that.

Bell siphons are tricky on a low flow system, so I would look at the "tipper" cup video I posted of some college kids that developed it to solve the issues surrounding the bell siphon.  Works like clockwork.  I came up with basically the same thing based on the japanese "deer scarer" Oshi Shidoshi, not sure about the spelling.  I split a small stream from the bed fill to the tipper which dumps on a regular cycle into the bell siphon gravel guard.  This gives the surge necessary to kick the siphon, and the filling period of the tipper allows for the siphon to break when the bed is drained.

[TCLynx]

Having stuff drain to the sump is more just for the ease of heights since the sump has to be the lowest point, it is generally easier to drain to something lower.  Especially if you are dealing with siphons, it is better if you don't restrict your available fall too much since they work better with a little more height to work with.

If the beds can easily be enough higher than the fish tank then letting the beds drain to the fish tank is fine.  Actually better in some ways.

[Rick Stillwagon]

Yeah I see your point.  I put my tanks in the "basement" so my beds wouldnt have to be too high.  If he sets his tanks in the ground a bit or uses a raised platform at the beds, it would keep everything accessible enough to use the IBC totes.

[David Schwinghamer]

Your idea is very close to what Im building now. This is the chop 2 configuration.

[James]

Off the topic of this discussion but I was wondering if anyone has ever tried or thought of converting a hot tub into a fish tank. I looked on Craigslist and it seems you can pick up free hot tubs all over the place.  Some work, some don't. I would think the plumping could be plugged or even converted to act as a pump. Might be a crazy idea but  for someone on a budget I wonder if it would work. Here is an example of the type of posts I found of people just giving them away. http://denver.craigslist.org/zip/2708895152.html

Thoughts?

 

[TCLynx]

Yes people have used hot tubs as fish tanks and sometimes even grow beds.

You want to make sure that any pumps or plumbing used has no metals other than stainless steel. And any spa air blowers are oil free.