Two beds with two bell autosiphons

[Eric T]

Hi, I just read Sylvia's book, and she talks about using indexing valves to switch from one bed to another, but these valves seem to work only when the water flow to it stops then starts again, which would happen naturally with a timer system.  However, what if I have bell autosiphons in each bed, and I still want to switch between them, giving each bed a little more time to be completely drained?  That is, instead of just a simple tee splitting the water between beds, and having the siphons unsynchronized, and using more water from the fish tank, it would be nice to do one bed at a time.  While one bed is being filled, the other bed is completely drained.  Has anyone ever done such a thing?  Thanks for your help.

[Japan Aquaponics - アクアポニックス 日本]

Hey Eric,  any particular reason you want one bed completely empty while the other one is filling?  Is that just an aesthetic thing on your part... because the grow beds themselves don't really care   ... or are you just trying to minimise water taken from the fish tank so you can run two beds without a sump?

[RupertofOZ]

It's hardly worth worrying about indexing, or sequentially filling two grow beds.... indeed, I can't see any point in doing so...

 

And the "aquaponics valve"... the indexing valve... can be made to work with continuously pumped "siphon" systems... if required...

 

Talk to TCL....

[Eric T]

Hi, thanks for the reply.  Yes, with multiple grow beds I'm concerned that occasionally the autosiphons will both be synchronized, and a lot of the water will be removed from fish tank.  Also, though I have no experience with autosiphons, my impression is that the plants spend a lot of time underwater, as compared with a timer system.  So, maybe some extra breather time might be good for the plants?

[Japan Aquaponics - アクアポニックス 日本]

The plants will be absolutely fine on a siphon cycle - they get lots of oxygen when the siphon kicks in and the rapid drain draws the oxygen down to the plant's roots.  How big is your fish tank and your grow beds?

[Eric T]

I'm trying to design a low-cost system for 3rd-world use.  The fish tank will probably be a hole in the ground with pond-liner.  Grow beds will probably be some plastic tubs.  Thanks for your help!

[RupertofOZ]

Low cost design for 3rd world use.... probably unreliable power supply, hot temperatures, low knowledge.... tank in ground, growbeds above... small tubs...

 

KISS....

 

Just go "constant flood"... and add a battery backup air supply.... you'll probably need to go solar anyway....

 

The problem is... while all that will work... such a small system will hardly feed a family...

[TCLynx]

While some plants might do a tiny bit better with a bit more dry time, the bio-filter won't so sequencing a system with siphons is something I don't recommend (since sometimes the siphons won't kick as planned and you might wind up with the bed sitting full instead of sitting empty and you really mess things up.)  If you want to sequence I recommend the stand pipe drain with the indexing valve.

If you want to do it in 3rd world with minimal access to "stuff" then as Rupe says KISS.

[Eric T]

Great, thanks for the advice, all.

[Averan]

adding a barrel or another lined hole in the ground for a sump would solve your issues with fluctuating water levels in the fish tank.