Aquaponic Step System, will it work?

[steve]

This idea would be to use one pump, from bottom tank to top growbed. Water would then flow through a series of tanks and growbeds gravity fed down a sloping landscape. Depending on the size and number of growbeds, and design it would probably require a reservoir tank with no fish to pump the initial inflow to top beds. The purpose being to reduce electric use and pump expense. In my example I would use 1 pump for system.  Usually would require 4, 1 pump for each tank. I would use a bit larger pump to add for elevation and extra aeration. Whatcha think would it work? Wish I would have thought of this before I built a large tank, will be harder to build 4 or 5 more large ones.

[TCLynx]

I'm not sure that you will save on electric use by this.  You still need to move the total volume of the fish tanks each hour and needing to lift higher to do it is going to use more electricity than a single pump moving that same volume at a lower head.

 

Looking at the drawing I can't quite see how you are going to manage a cascade from bed to tank to bed to tank either since the grow beds are lower than the tanks.  To drain from a grow bed into a tank the bottom of the grow bed needs to be about as high as the the water in the tank.

 

Also, by a glance at the drawing, it looks like you have planned twice as much fish tank as grow bed.  That is backward to how I would recommend it be designed.  I like to have twice as much grow bed as fish tank.

[steve]

Ok I'm very new to this sketch up, couldn't get my elevations to look right. And yes being a fisherman I'm a bit biased towards fish. But just trying to get some feedback on the theory. Still seems like it could save half the electrical I'd think?

TCLynx said:

I'm not sure that you will save on electric use by this.  You still need to move the total volume of the fish tanks each hour and needing to lift higher to do it is going to use more electricity than a single pump moving that same volume at a lower head.

 

Looking at the drawing I can't quite see how you are going to manage a cascade from bed to tank to bed to tank either since the grow beds are lower than the tanks.  To drain from a grow bed into a tank the bottom of the grow bed needs to be about as high as the the water in the tank.

 

Also, by a glance at the drawing, it looks like you have planned twice as much fish tank as grow bed.  That is backward to how I would recommend it be designed.  I like to have twice as much grow bed as fish tank.

[TCLynx]

There are some drawbacks to trying to cascade systems.  Think if you pump to a grow bed for 15 minutes out of the hour to get it to flood but then the grow bed is going to be draining slowly though the holes in the base of the stand pipe so the next fish tank and grow bed are going to only get a slow flow to them and the rest of the grow beds won't flood since they will be draining as fast as the first one is filling them.

 

Now I've heard of people trying to set up a cascade with siphons but this will be pretty tricky to make sure you don't wind up with all the beds full of water and only trickling over while the sump tank has run dry unless you still have a sump tank big enough to handle all the flood and drain water.  Still the cascade idea has been tried from bed to bed but it is tricky to make sure that the top beds drain will be big enough to ensure the next bed will flood and kick over the siphon, especially with the fish tank to slow the water flow into the next bed.

 

It could perhaps work but getting it balanced will be really tricky.

 

As to electrical usage, well need to know some heights to have an idea of what you will be dealing with.  How deep are those grow beds going to be?  Each elevation will need to be at least the height of the grow beds plus a few inches.

[steve]

Thanks TC, This is not something I'm planning to build now. As I have my hands full as it is. The concept came to me and I thought it might be of some use. I do realize it would be tricky. Just seems we'd only have to pump 1000 gallons to refresh 4000 gallons or more to system. Construction costs might be higher and landscape would have to slope correctly. I would use minimum elevations as necessary for continued flow. Would be nice to reduce pumping cost.

[Raychel A Watkins]

Aloha Steve

 I live in Hawaii and one of my WWOOFers who was an engineer by education designed and built me a system sort of like what you are talking about.  It entails 4 250 gal IBC tanks burried at different levels in the ground.  There are 6 grow beds at this time.  I will probably add more if I can figure out how to do it.  He had me buy a pump that would push 850 gals 8 ft high.  The sump tank is only about 25 gals where the pump is placed.  It has been running for almost 7 months and it is a marvel.  There is a flaw or 2 that need to be worked out but the pump does not go draw in the small container and the fish are well and the plants are gorgeous and produce everything imaginable.  Go to the videos and about page 7 I think there is a video called Matts Engineering Miracle and I show the whole system and how it flows.  If You want more pictures I can up load some tomorrow.  This video was taken in Jan so it was very young but it works wonderful.

Now if you ask me if it saves electricity I don't now but I only have to clean 1 pump each week.

Good luck

[TCLynx]

Ok so looking for pumps that will move 4000+ gallons per hour at say what 12 feet?  Most of those I'm finding are over 5 amps or over 500 watts.  (Keep in mind most inexpensive 15 minute interval timers are not rated to handle turning a pump like this on and off.)  And remember that start up amps on really big pumps is going to use more electricity.

 

Now I don't know about really being able to cascade an "unlimited number of tanks/beds" and it would be pretty difficult to make a comparison with unlimited since we don't know the head height for unlimited.

So going with the 4 tanks each 1000 gallons.  If you were to simply hook the 4 together and flood 4 beds that are just high enough to drain back to the fish tank or sump tank and hence not dealing with any more than say 5' lift.  And you still wanted to do the timed flood and drain (provided you get a timer that can handle it, there are propeller pumps that could move that much water at the lower head height for about the same amount of power.

 

However, if you were to use a constant pump and siphons with the system all set up roughly on a level, you could run the same 4000 gallons of fish tanks with a pump that uses between 300 and 400 watts and provides constant aeration to the fish tanks (avoiding needing to run a separate air pump running full time to all the fish tanks.)

 

Now my preference would be to separate the systems into 4 separate systems (seeing as then you don't have the worry about a disease or problem in one tank doing in all of your tanks.)  I know of many small pumps that can handle a 1000 gallon system depending on how it's configured.  Now this may not be a big savings on electricity but the redundancy and constant flow for aeration has benefits.

 

Keep in mind that for the cascade idea, you probably need the sump tank to be equal to all the fish tanks combined.

Sequencing might be easier than cascading.

[steve]

The main benefit of this system would be I believe you'd only need to cycle 1000 gph. Being as our 1000 gallon tank would cycle through totally, 1000 gallons of filtered water to each tank for every 1000 pumped. So in theory if you had 10 tanks cascading. By pumping 1000 gallons into top, you could cycle 10,000 gallons.

 

[Chi Ma]

What if you used a pump with a float switch? It will pump out the sump until the float switch kicks off. Then you wouldn't have to worry about a timer.

 

 

Pump

[steve]

Thanks all for your inputs. Good idea Chi, Then when sump is empty it would automatically wait for the cycled water to come back to sump to start again. OK enough of my step dreaming for today. I have enough real work here to dream about. Thanks!!