Backyard Aquaponics
A place to discuss aquaponics

I'm looking for a way to automatically transfer liquid from an RFF to a mineralizer one slug at a time. Has anyone done anything with automatic valves where gravity is what's driving the flow? I'm looking for some recommendations on what kind of valve and brand to use. The difference in water level will probably only be about 4 inches.

I’ve always wanted an excuse to build one of these:

http://aquaponicslab.org/uncategorized/water-valve/

http://aquaponicslab.org/how-to-build-an-air-actuated-water-value/

Most valves rely on line pressure to reliably operate.

Some valves are designed for use in rain water systems but they still need a bit of head pressure to function.

If I ever get around to setting up something similar I'd probably use a central locking actuator to opperate a standard ball or butterfly valve

Having a pair of valves with a chamber between would be a safer proposition. Top valve opens, crud falls in and valve shuts, bottom valve opens for the crud to flow out.

There is then very little chance of both valves failing and water flowing freely

There's been a lot said on automatic valves needing a certain PSI to operate and the potential for blockages. They are not designed for dirty water so fish solids would cause problems.

https://www.smarthome.com/smarthome-sel ... 2v-dc.html


TCLynx wrote:
The average inexpensive irrigation solenoid WON'T operate with less than about 6 psi of differential pressure. AND it will get all clogged up with the gunk since they are designed for clean water operation.
Most solenoid valves I've seen that will handle operating with no differential pressure constraints cost hundreds of dollars in which case you are probably better off buying one of those swimming pool valves that can be operated with the 24 VAC motorized actuators. If you are into electronics you can create a controller for one of those. I did it with a picaxe M8 chip a DPDT relay years ago.

Hmm . Some interesting replies, thanks guys. Scott_dc, I'm going to have to look at those valves some more - I'm not really sure what I can do with them but they're pretty neat. Motorized ball valve might be my best bet. I notice that some of the rain barrel systems use a motorized ball valve with timer setup that's like a hose end timer - Toro #53746 Battery Operated Hose End Timer. I think most of these gravity fed units have a strainer so I don't know about using it for solids but it's cheap enough it might be worth a test.

Using a pump instead might be a good bet as well.

Lastly, I might still try a continuous flow to the mineralizer like web4deb since that's a cheap way to go compared to the motorized ball valves. Any other ideas?

Quite a few years ago I took to bits an expensive air conditioner unit, it used a peristaltic pump to drain the water out of the bottom of the unit controlled by a simple float switch. Those pumps are nice because they are PDP's can run dry and will move crap,just a thought.
Edit
When they are not operating the don't allow liquid to flow and are also used as dosing pumps because the water transfered can be fairly accurately controlled.

Many years ago on the forum there was a thread on automatic valves and I think someone worked out a way to modify garden solenoids to run on low pressure unfortunately I can't remember what the result was

I remember using peristaltic pumps back in my lab days for dosing additives into a fermentation vessel.

I once suggested a small geyser pump driven by the change in air pressure in a sealed barrel to move crap out of a filter bottom but Milne called me a *sigh*.

12v peristaltic pump from china on ebay for approx $40 au, 400ml per minute.

It's hard for me to imagine solids making it through a peristaltic pump without getting chopped up pretty well (not that it's a bad thing to have happen - probably actually a good thing since you're trying to break them down). Even tougher to imagine the solids making it into a tiny tube so I could also see solids accumulating on the bottom of the RFF and never coming loose with a 40ml per minute outflow rate . Interesting idea, certainly a good way to regulate the volume removed.

That is interesting. Once the solids are in the mineralization tank it might be good to frappe them with a dirty-water-pump?

If your mineralization tank pump has a Frappe setting Brian then go for it .

Actually with all the agitation from aeration, the solids probably get pretty chewed up anyway .

Mono pumps handle solids quite well

They also produce decent pressure, useful if said solids block up a pipe.

Small ones that may suit pumping out a filter as well as solar panels and other stuff are available from tuhorse - it's Chinese stuff but never caused me issues

I've pondered using a solar mono pump to run a solar heating circuit. The pump would handle the pressure with gentle flows. Being solar it should only come to life when the sun is warming the black pipes...

You got a link for that Sean?
I have a mono 3 phase used to pump out the septic tank but it was very pricey.

http://www.tuhorse.com.au/solar-pumps/

Helical screw = mono

A bit like hook and loop tape = Velcro

They're not exactly free, but they're cheaper than some alternatives

Might be able to get similar pumps from alidirect or whatever it's called