Backyard Aquaponics
A place to discuss aquaponics

TimC, yeah the timer idea is basically good enough. I was just wondering if any extra energy efficiency could be gleaned by not having the GB overflowing.

Yesterday I thought perhaps a 12V bilge pump would make it easier - don't need such a substantial switch then, which means it's easier to actuate. A 12V pump could then also go hand-in-hand with running a battery backup and even eventually powering the whole thing with solar - in which case maximum efficiency would be exemely welcome.

So far the electronic solutions seem to win in the popularity stakes, but for someone like me the mechanical system is more understandable and I think can be made to be reliable.

As long as water can't gum it up, mechanical is better.

The only thing in the water is the float, with the switch and washers located in a vertical pipe sticking up out of the growbed. Only problem I see would be humidity.

The main issue now is finding a mechanical switch that allows sufficient current and voltage with minimal actuation force. Hence the appeal of a 12V bilge pump. Any ideas?

Are you pumping filtered water? so there can be no solids buildup?
If so, I'd go with your design, but think about the sliding float, I reckon that's a neater solution.

How about switching the water, not the pump, and let the excess water run back into the tank for aeration. Valves take less power and voltage so are easier on any switch setup. Does any one know of a workable valve that operates at very very low pressures, like .5lb (15cm head)? I found that irrigation valves at my local hardware take a lot more pressure...

yes, and they cost a fortune. They're called actuated ballvalves.
However there was a link to EllKayBee's thread earlier in this thread, and he had door actuators opening a flapper valve, very nice...

KP, the pressure sensors are from freescale (www.freescale.com)

MPX2010DP PRES SEN COMP 10KPA

The Cat5 is good enough for my use, I have 300m to spare. For analogue stuff it is ample. Plus it won't matter if it gets a bit wet. The runs will be less than 10m.

Here is a summary of the system, it needs to be updated to include the later version of the water level sensor and the use of the light actuated kits purchased from Disk Smith and suggested by TimC (camera batteries are flat )

http://www.backyardaquaponics.com/forum ... php?t=2014

The problem of the steel shafts rusting was fixed by cutting a length of 3mm tubing and slipping it over, then using silicone to seal both ends...also use plastic cleaves to connect to flap instead of steel (the steel connecting rods lasted a month)...now been working for over 5 months now

Will update the link with pics tomorrow...just as aside, I tried having a float going up and down in a cylinder by water, problem was having it working consistently at the same water level each time

ummmm yeah and your point is? ::rolls eyes::

Signal/switch was not under water

lol just pm'd you....yeah not sure why you included me in that one bro coz I only corrected kp with his IP ratings lol.....nuthn to do with jims diagram lmao....maybe you were aSLEEPE when ya read it

Always aSLEEP E BK Thanks

best way to be I reckon

I'm intrigued by the elegance of the CHIFT PIST system (Joel's Second System) and have already rushed out and bought 3 of the 500 litre tanks, inspired by Himzol's low-cost setup.

Any way, I am assuming that by the time the water reaches the sump tank (where the pump is), all significant solids will have been filtered out by the growbed. Therefore I don't need a pump that can handle solids. A 12-volt bilge pump is cheap, efficient and should integrate nicely with a car-battery backup.

ok.
1. I have heard that some people have had issues with bilge pumps, but believe this may only be for continuous running. I suggest you do a search.

2. Solids will accumulate in your sump, but any pump should handle these as they'll be very fine.

3. Fine solids will still gum up a float if given the chance - this is why I asked the question.

4. CHIFT PIST is great imho, and I designed my system this way before finding the forum, so I love it.

5. Is a bilge pump efficient? It will certainly be very low pressure, and I wouldn't expect it to pump to any great head, but stuff that runs off an alternator from a fuel powered vehicle (such as windscreen wipers) are often inefficient, as efficiencies are not so important in the scheme of things.

Good luck mate. Hope all goes well for you.