Timed siphon valve - automatically alternating between constant flood and flood & drain

[Averan]

Am I crazy or is this a crazy good idea?  :D

I've been thinking of the many benefits to a constant-flood setup, but I also like flood & drain with a siphon.  My crazy idea is to use solenoid valves on a timer, connected to the top of the siphon, to break the siphon whenever I want.  Instead of passing water through the valve, I'd just let air go through.

Some people, myself included, have cycled between F&D and C-F by opening the cap off the top of their siphon.  With a timed solenoid we could control this automatically!

All you need to do is open and close a small air hole to either allow the siphon to function (F&D) or to run constantly overflowing (C-F).

This setup would allow us to run C-F during the heat of the day to minimize evaporation and heat gain and then switch to F&D at night to maximize oxygen and aerobic bacterial digestion.  In the winter this could be reversed, running F&D by day to pick up heat stored (in a GH) and C-F at night to minimize heat loss.

While keeping the pump on constantly does not conserve electricity at night, it has been known to increase the life of the pump.  It's also helpful to maintain flow through the fish tank which is why I've never really been a fan of putting the pump on a timer.

Am I missing something obvious here or could this be a really great and useful idea?!?

Now I just have to rig up a test model....

[TCLynx]

Hum, well if you know how to tinker with solenoids then I don't see any problem with it.  Keep in mind some solenoids are not designed to be activated for long periods of time without melting down and most of them need continuous power to hold them open (or some need it to hold them closed instead depending on if it's normally open or normally closed.)

Now you say a solenoid valve.  If you are thinking like a simple irrigation solenoid valve, you may run into the problem that they need a rather large differential pressure to operate since they are already only using the solenoid plunger to just seal up or not seal up a little hole to allow air in and out from behind a diaphragm which is what is actually letting the water flow or not.  If there is not enough pressure, the valve won't open anyway and if you were thinking to just install an irrigation valve on top of a bell of a bell siphon, I fear it may not work.

The other option would be one of those little pinch type solenoid valves to pinch off the air tube or not, that you will probably be able to find and get to work at 0 pressure.

[Averan]

ok, well screw the solenoid.  all i need is a tiny motor that can pull a small lever to open an air valve of some sort.  i'm sure i'll have to tinker together the parts, unless someone knows of any low-power motorized valves that might be close to what i'm envisioning?  anyone?  :)

[TCLynx]

Well you don't have to drop the idea of solenoid, you just have to do a little more internet research to buy it instead of just picking one up at the big box store.

[RupertofOZ]

Not a crazy idea Averan... but a hell of a complicated way to acheive a simple plan...

 

Just ditch the siphon...set up your system with an overflow standpipe (two holes in the bottom of the standpipe)...

 

And get yourself a timer, mechanical or digital..... Bear with me...

 

Just set the timer "on" during the day.... the overflow standpipe will act like a "constant flood"....

 

Then when/as night approaches... the timer/pump will "off".... draining the grow bed... until the next timer/pump "on"/"off" cycle... perhaps 15/45, or what ever intervals you want..

 

Etc, etc... until the timer/pump becomes permanently "on" during the day...

 

KISS....

[RupertofOZ]

With the setup above....

 

You can vary the length of the constant flood period... and/or the timer "on/off" F&D... to your hearts content... or to seasonal variations....

 

Just by altering the timer program...

[TCLynx]

That is the simpler way to do it Rupe but he was trying to avoid turning the pump on/off.

[RupertofOZ]

Sure.... but from my experience.... turning the pump off and on.... as long as the "switch" interval isn't short and repetitive... ie  less than, say 5 mins.... or more than a couple of time an hour... then pump life generally isn't affected...

 

Many pumps will actually list the max on/off times per hour...

[Averan]

hmmmm...well, thanks for the input, but I really do prefer to keep water flowing through the fish tank, especially if trout are involved.

my concept is technically very simple and if I can think of several ways to DIY a solution there must be something out there already that works or at least comes close.

instead of having one pump that when switched off for 45 minutes shuts down all water flow throughout all growing modules, i'd much rather be able to modulate that flow only as much as needed.  I thought that since all I needed to do was affect whether or not a siphon was sealed, it would be a simpler task than trying to go the solenoid or indexing valve route.

[TCLynx]

Look for a solenoid valve that can pinch the air tube to the top of the bell on a siphon.

[Averan]

Found one! http://www.biochemfluidics.com/Products/pinch-Valves.asp

Now I just need to find a controller/timer for it.

[TCLynx]

To operate it, just get a timer of some sort and a wall wart type adapter of the right voltage and everything to operate it.  make sure you wire it correct and simply plug the wall wart into the timer and set the timer to let open the valve when you want constant flood and close the valve when you want the bell siphon to work.

Make sure the bell siphon is built to allow the bed to run constant flood without overflowing over the media (enough space between the bell and stand pipe to let gravity flow drain it at the same speed that the bed is filling without the need for the siphon fast drain to keep up with it.)

hum, those seem a bit more $ than I would spend on the project though.  Seeing as you probably need one for each siphon.  Hum, Well I suppose you could run tubing all over from each bed to a single valve as long as you make sure it is big enough to make sure all bells have a big enough air break.

[Averan]

i just realized your approach won't work simply because the snorkel tube will be closed off by the water.  i need to bypass the tube entirely.  perhaps i could put a T in it at the top and then put the pinch valve on that offshoot..

i'll be looking to source more affordable parts.  and i might go back to my idea of a simple sliding gate valve of sorts, or ball valve.  it really shouldn't take much force to open/close and therefore shouldn't need much of a motor.

ideally, this is a small/compact mechanism that can be fitted right onto the top of each bell siphon.  it would be a siphon cap.....an automated siphon bypass.

thanks for the input and for bouncing my ideas back!  =)