As I get a petitioned waterproof room set up in the walk-in basement for an RAS, I'm wondering if there is a simple devise that will start a 12 volt alternate pump if the 120 volt power goes out?

I'm going to be using a pump to drop water thought a trickle biofilter/aerator that is powered by 120 volts. But if the power goes out that will go dry killing he bacteria if I don't crank up the battery powered pump in time. I could have another pump hooked up on a 12 volt battery as a back up, but would there be was some way to break that 12 volt circuit as long as there is 120 volt power, and open the circuit if there was a 120 volt power outage...?

Something similar to this concept?

http://www.freepatentsonline.com/3976986.html

Cecil, you could run a 12 vdc pump 24/7, off a battery with a constant trickle charge from 120 vac. No switching or power outage detection needed.

Not sure what you mean. Would the 12 volt pump have to be the primary pump then vs. the 120 volt one I have?

OK Cecil, here's a Rube Goldberg set-up. Get a photo electric switch, the kind you screw into a light socket then screw the bulb into. hook the photo socket between your battery and pump, put the socket, and a small light bulb in a box. the light will keep the photo switch off, when the power fails the light goes out and the photo switch will turn on, and allow power to flow to the pump. The photo electric socket switches cost less than 10 bucks.

Right - in this concept, the 12 vdc pump is the only pump.

Alternate method uses a 12 vdc battery (with constant 120vac charge) to run the 120 vac pump, through an inverter. Basically a DIY Uninterruptable Power Supply.

O.K. guys. I will run this over with the electrician in the family (my dad) who worked 21 years as an I & R man for the local phone company. He's also an engineer at heart and loves putting things together and figuring out ways to do things.

Today he is going to help me seine the bluegill pond.

You could buy a cheap UPS on eBay. I guess it depends on how long you think you will need to run with no power.

The bacteria in a biofilter will last a long time without water.

A decent used backup power supply (UPS) with a dead battery would make a good candidate. You can probably get one for free if you look around. I've got three sitting in my attic awaiting planned projects that I've yet to get to.

Pull out dead factory installed battery and rewire the battery terminals to connect to a standard deep cycle marine battery.

I've done this before for various projects, and it works great.

Here is a good example:
http://www.dansdata.com/upsupgrade.htm

Cecil,

I don't know how your design is going to work but how about having water come in at the bottom of the container that is holding the biofilter media and out at the top.

You could add a check valve before the water enters the container to keep it from draining.

Phil emailed me and said the following:

HI Cecil,

All you need is a relay with a 120vac coil. AC power drops, dc power on within milliseconds.

If you need help, let me know. It is much simpler than the others responded to.

Glad to help,
Phil

Thoughts?

That's a thought Chris. I may consider that. However my plans were to pump water up to a packed column, and use the packed column as both an aerator and a biofilter. In theory (my theory) this would preclude the need for a powered aerator and reduce electrical consumption. Of course if water stopped pumping up to the packed column due to a power outage with no back up, the packed column would go dry and not only kill the nitrosomonas and nitrobacter bacteria, but also stop aeration. Hence the need for immediate back up. I'm seriously considering a back up of a submerged filter and a packed column to create some redundancy and more biofiltration. I would think more biofiltration cannot hurt vs. not enough.

Cecil,

I'm glad to see that Phil contacted you because I was just about to make the same suggestion. All you need is a simple relay. WIth 120v voltage detected the 12v side of the system will be open, but once the 120v power goes off, the relay will switch and close the 12v circuit and your 12v pump will kick on. When the 120v power is restored, the 12v side of the relay will open back up and disrupt the circuit to the 12v pump.

You might also consider using a small 120v powered trickle charger to keep your 12v battery charged all of the time until the 120v power fails. Make sure to not set your 12v battery in direct contact with the concrete basement floor as this will cause a drain on your battery. Good luck. Shawn

Thanks Shawn and Phil and ALL!

Could you arrange the drain from the stacked column through a standpipe, so that it stays full even when not pumping water.
A pipe that draws from the bottom of the stacked column and then exits out the side of the column?

Matt Wehland

I'm just sitting here thinking and the stacked column needs to have water flowing through it, but not be full of water to function, correct?
The media need air to function.

Then my idea won't work.

Matt Wehland

Chris:

So I'm just connecting a deep cycle battery to the UPS instead of the gel battery, and plugging in the AC pump to the UPS. When the power goes out power is then routed from the deep cycle for however long the deep cycle lasts?

Can I connect the DC pump to it instead and have it come on only when the power goes out? I'm only asking as I'm thinking the DC pump will run longer on the battery charge.

How can I figure out how long the battery will last, and can I hook a couple batteries in series like on the link? Do I need to hook up a trickle charger to the battery to make sure the battery is fully charged when I need it?