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Bell siphon

Mostly grow organic in dirt.  Have played with aquaponics, but it was all electric with timers to move the water.  Want this coming year to go with 12 volt pumps to move water constantly, solar with a fail over to house power. Not a challenge, fairly simple.  What I do not want to do is to use electricity to turn pumps on and off to fill and drain the flood tables.  So I am looking into bell siphon set ups using pvc.

Has anyone experimented with bell siphons and could you post pictures?
 
I used a system of this sort for several years with good results. I don't have pictures readily available, but here are a few things that might be useful. I made my beds 4'x4'x1' approximately by using 1x12 lumber to build a frame. I cut a piece of EDPM rubber to fit inside the frame to hold the water. Under the rubber there was a 4x4 piece of plywood. I did not attach the frame to the plywood; this made it much easier to move the setup when needed. I allowed about 4-6" water to fill the bed before draining. My nutrient solution was contained under the frame in a 110 gallon tub filled with 100 gallons of nutrient; it was easy to make a large batch of nutrient periodically, and drain the remainder every couple weeks as a feed for other plants. You only need a small pump to fill the bed; this insures that the media have a good time between floods to get air. I used perlite, but did not like it because particles got all through the system. Clay balls were much nicer to use, and worked well. I also used rockwool mixed about 50-50 hydrophobic and hydrophilic. The rockwool tended to stay too wet for my plants. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/bio-10.pdf is a good article about construction. I would particularly point out figure 16; the elbows are very very useful, if not essential. For safety I also put a very small drain in the bed which continuously drained the bed at a slower rate than the pump filled. Should the bell fail, some water would still go to the pump, helping to keep it cool, and not burning out. Have fun.
Renais
 
Thank you.  My thinking involved two bell ciphons for fail over, one a bit higher than the other, but like the additional drain as well.  Other strange ideas.

Resevour at bottom uses pumps to feed resevour at top.
Resevour at top has overflow back to resevour at bottom.
Resevour at top uses gravity to feed to grow tables, rate adjusted by valve(s)

Theory being, if electricity / solar / battery fails if the resevour at top is large enough it will provide fail over protection till the water runs out.

Thoughts?  Building into the side of a hill.  Hoping bottom resevour to be a clay pond but worried about filtering out nutrients when filtering out clay.
 
I would be most concerned about a clay pond.  Most clays will bind nutrients quite easily and asymetrically, leading to a poor nutrient feed.  I'd highly recommend lining the pond with a non-reactive layer.  There are small valves that can be used to configure a slow drip from an upper reservoir to the plants; the ones meant for 1/8"  or 1/4" drip lines work well.  I use longish (maybe 8-12') lengths of the line instead to provide a small flow.  The valves may clog, or be accidentally closed, while the lines tend to stay open and in service.  The drip line is so cheap that the line also costs quite a bit than the valve.  If you use a drip line as emergency backup, you could split it into multiple ends which could be placed directly on top of the pots.  This way you do not need to have a large amount at the bottom, and the plants will be more likely to get at least a little water.  Even in my pretty dry environment, a drip feed of 200-400 ml/day is enough to keep the plants alive in an emergency, so you don't need a huge emergency supply, in my opinion, especially if you were willing to hand supply some water to the system every few days in an extended power outage.
Renais
 
On clay pond: They already exist and make up our back fence line.  Every 12 foot is a row that drains the garden from south to north.  Miniponds run East to west, feeding each other down an incline.  The bottom pond is stocked with goldfish which will be Koi.  Threw some feeder goldfish in to test, now I have monsters that keep breeding.

Anyway, will probably build clean area and feed that with filtered pond water.  Then use that area for the aquaponics.

PS - Alread do aquaponics of a sort with rafts / floaters in the bottom pond.  I grow corn the way most grow tobaco.
 
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