Water Pressure Puzzle

[William J Silverthorn]

I have a challenge that I believe has no solution but I dont have the experience to make a final judgement.

I'm trying to design an indoor / outdoor setup at my university's childrens center, that will allow the fishtank to stay indoors, and have a water line lead out to a growbed outside. the point is to allow kids access to the veggies but not to the goldfish.

the problem I'm having is, so I dont have to worry about flooding issues, I wanted this to be a gravity fed system off of a single pump, but with the extra distance between the garden and tank, as well as having to send 2 water lines through a wall, I dont see how I can make this work with only one pump.

any ideas?

[Jeffrey Ihara]

How much distance are we talking about? If the growbed is just on the other side of the wall, I don't see why a regular CHIFT-PIST set up wouldn't work (with the growbed and sump on the outside, of course).

I would advise you not to suggest pee-ponics to the kiddies, though.

[William J Silverthorn]

these are toddlers so no peeponics of course, just trying to maintain a fertile, enjoyable, fun and successful first farming experience for them. it should be a fun project if I can get it to work right.

this could be right next to the wall if it has to be, but the water would still have to travel back and forth through the wall... which is not ideal for low pressure gravity fed draining...

If I use a bell siphon to create pressure that might do the trick going one way while the pump takes care of the other direction, but then I guess the sump would have to be indoors with the fish tank.

Also with that set up, the fishtank would have to be lower than the growbed or the siphon would not fire.
these are toddlers, so the growbed is already pretty low... not sure if there is room for this plan... ugh

How would you get it to work with the sump outdoors?

[Keith Rowan]

keep the whole thing indoors..

use a double rack fish tank with your bigger tank on top.. it overflows into a growbed (next to a south facing window, which drains via siphon into the sump under the ft.. there you pump it back up to the ft..

bright and colorful ornamental fish will be a treat for the kids to watch

[David - WI]

A pipe running through a wall... is just a pipe; there's no penalty for passing through the wall.  Distance (unless you're talking 100's of feet) isn't really a big problem either as long as the pipe isn't too small for the job.

If you put the fish tank up high (eye level?) over the sump, and the sump as low as possible.... you should have plenty of drop each way.  If you pump up to the fish tank from your sump and then let the fish tank overflow out to the growbeds... the growbeds will drain back into the sump.

The fish tank level will stay constant, you can add top-off water to your sump easily since it's sitting on the ground, and your growbeds can be close to the ground.  Your "in" and "out" pipes can both pass through the wall at the same height, beneath the growbeds; so you don't have a lot of exposed outside.

You can put a shallow "pan" around the sump that also drains out through the wall so that if something plugs up and overflows it will just run outside the building.

You need to worry more about the vertical height difference between the fish tank, grow bed and sump and not so much about the wall or the distance between the components.

[Alex Veidel]

If these are toddlers, you might want to reconsider giving them access to the plants :) It may be a fun gardening experience for them, but it probably won't be successful. Unless of course you are talking about access under supervision.

[Jeffrey Ihara]

honestly though, for children that young, planting seeds in soil would be my choice. 

The learning opportunities offered by aquaponics are not really accessible for kids at that stage of their cognitive development (or whatever the psycho-talk term is nowadays). Once they reach the point where they can talk about bacteria and nitrogen cycling and integration of metabolic pathways, then the value of having a resident AP garden becomes substantial. I'm not sure what age that is, but "toddlers" seems a crowd that would benefit more from basic lessons like "what are bacteria?"

[William J Silverthorn]

well, thats true they are definitely too young to teach AP to.
its partially for them to play with under supervision, and partially for introducing the concept of AP to my university as a training model.

Also there are other soil planters already being used in the garden, but I'm hopefully adding a single limited AP demonstration to the garden. So if I let the nitrates run high, I can partially change the water and give the other dirt planters a nice fertilizer boost.

Jeffrey Ihara said:

honestly though, for children that young, planting seeds in soil would be my choice. 

The learning opportunities offered by aquaponics are not really accessible for kids at that stage of their cognitive development ...

...

David, thanks for the design idea. That is much simpler than what I had imagined.

David - WI said:

...

The fish tank level will stay constant, you can add top-off water to your sump easily since it's sitting on the ground, and your growbeds can be close to the ground.  Your "in" and "out" pipes can both pass through the wall at the same height, beneath the growbeds; so you don't have a lot of exposed outside.

...

Keith thanks for the suggestion, but unfortunately all of the south facing windows are office or executive spaces that I dont have access to. So I'm not likely to have ample sunlight without putting the GB outside with the rest of the planters.

Keith Rowan said:

keep the whole thing indoors..

use a double rack fish tank with your bigger tank on top.. it overflows into a growbed (next to a south facing window, which drains via siphon into the sump under the ft.. there you pump it back up to the ft..

bright and colorful ornamental fish will be a treat for the kids to watch

[David - WI]

Is there a window that you could place the fish tank in front of, so the kids could view the fish from outside the building?

Even if you had to make a little "ramp up... platform in front of the window... ramp down" viewing area with a railing; it would let them see the "other part" of the system.

[William J Silverthorn]

that probably wont be necessary.

if they are tall enough to use the planters then they should be tall enough to see inside the fish tank. I might get some extra interesting fish for them to look at. some pleco's would probably do nicely with the sunlight hitting all that nutrient rich water

[David - WI]

If you want to have any significant water pressure to feed the grow beds, the fish tank would have to be up fairly high... if you set it up like the sketch above anyway.

It takes a little bit more than 2' of height to make 1 psi of water pressure, so to get even 2 psi of pressure your fish tank would have to be about 5' higher than the growbeds.

[Jason A.]

As long as your Fish tank is higher than your grow beds you shouldn't have any issues gravity feeding your system. I was connecting some water hose one day to add some water to my system (well water) and I stuck the hose (about 150ft of water hose) in one of my rafts before connecting it to the rest of the hose and faucet. When I got ready to connect the hose it was draining water. The end of the hose was lower than the raft. Hope that helps

[Jeffrey Ihara]

I agree with Jason. The water level in the fish tank only needs to be higher than the grow bed.