Backyard Aquaponics
A place to discuss aquaponics

OK thanks, I'll look at pure sine wave inverters and try to find info on efficiency curves. It's a bigger spend but minimises the number of pumps, hoses, pipes, etc. I just want it to be as reliable as possible so we can go away for weekends and not stress too much.

Edit: I found a user manual for the 360W pure sine inverter from Jaycar, below. It says "Efficency test done at approx 75% load, with 13V input for 12V model, 26V input for 24V model". DC current is 40A (max?) and efficiency is stated to be 90%.

http://www.jaycar.com.au/medias/MI5702-manualMain.pdf?context=bWFzdGVyfGltYWdlc3w2OTIzNzV8YXBwbGljYXRpb24vcGRmfGltYWdlcy9oN2UvaGQyLzg4MzgyOTUxOTE1ODIucGRmfGY5NjFmYzZhZmRhMDcxOTExMTU3MDhmM2U1ZTBhMDNiMDg3YmE2ZjI2NzFhNGNhNDEwODczZjA5Y2Q3MmJmMGU

hello OBO
First visit to this discussion and only registered today.
Gotta tell you...the system you have described, with the addition of a 12v relay and power source has been what I hope to use in my new set up to be built early 2017 in Gympie. (Moving house October 2016).
I will be using this post (in my saved favorites) and the stuff from RobBob who sent me to your post as the main source of info.
Will try to keep photo records etc as I progress.
Thank You for this system...
Keep on keeping on with'n all this valuable info.

Just wondering how a 12 volt bilge pump (quality one like Johnson or Rule) connected witn a venturi would work. This way you have both water flow and air. Installed in the FT of course so the grow beds would not circulate in a blackout situation. Would this be OK or am I missing something? I would connect this using the relay and 12 volt supply like chainsaws original idea.

I am thinking of suspending the pump off the SLO pipe so it doesnt clog with waste or sediment

what are people's thoughts on the above

Don't know who Chainsaw is, but keep with 12 V for control valves, air or water. For circulation or air use 110 V. Besides 12 V running continuous for 12 or more hours, 24/7/365 you would burn up lots of them each year.

Yeah, from what I've seen people using bilge pumps full time end up replacing them every 3-6 months or so; which if you are running full solar or something you may not mind too much. But if you are talking about as a backup for when your main power is offline you should be good with a bilge+venturi or 12v air pump; just do some calculations of CFM of air per watt to see which is more efficient and will make your battery last longer.

Another good option is an APC UPS for computers, I had a used 350VA one for my air pump and it would run it at least 24 hours; the power was never actually off long enough to find out how long it would run before quitting.

You are missing the point. Chainsaw is the original poster of this thread. And if you read my post correctly you would see that this is a BACKUP system, not the main system. It is for blackouts only. I will be using a 240volt pump for the main pump which is what use in Australia, not 110volt