pump UV protector

[BillT]

I just made an electronic box that will prevent my pump and UV from running if the water goes low enough to trip a float switch.
It uses:
a float switch: $5-10
a 12 VDC power source: ~$5
a relay, activated by 12 VDC and able to control two 120 VAC circuits
some old extension cords and plug ends I had laying around.

I think I could have bought something for about $40-$50 that would control a single circuit.

Here is my circuit diagram:


Now I have to determine the low water level at which the pump will no longer effectively and mount the float switch a bit above that (lower sump water, drill hole, mount switch).

[BallAquatics]

Hey that's great Bill, thanks for sharing with us.  For me, building your own solutions is a big part of the hobby.

Do you have most of your tanks on a 'central system', or is this set-up for quarantine and such?

Dennis

[Mugwump]

Isn't there an easier way to mount the float, without drilling??...I like the design, looks like a winner...

[Mir]

That's awesome! ....I need to do something like that for my filters for when I'm gone.... Dx

[BillT]

Isn't there an easier way to mount the float, without drilling??

There are things you can buy (or make) for float valves or float switches that will hang over the edge of a tank with a mechanism that allows you to adjust the level. I think it costs about $30. Here is an example:
http://www.bulkreefsupply.com/reefkeeper-float-switch-bracket-kit-digital-aquatics.html
An non-adjustable version would be simpler to make. Maybe I'll try that.

Do you have most of your tanks on a 'central system', or is this set-up for quarantine and such?

It is for a new water system I have been working on for several months. I am setting it up in my main fish room where I have two other water systems running some lab racks I have for messing around with for my job. The Q-room has individual aquariums on racks where water is added automatically to the tanks. Excess water overflows out bulkhead fittings to one of the floor drains (which I also made). A flow through system is considered best for disease control because the water from one tank can never get to another tank through the water system. However the water quality is not so easily maintained, which is why I am setting up the new water system in the non-Q-room. I just took some fish room pictures but I think I'll put them into another post.

More on prices:
relay: $12.99
relay socket: $10
box: $7.50

[BillT]

Here's a picture:

[Mugwump]

Could that relay handle more than one tank??.....

[BillT]

It is intended for a water system which will serve 10 or 15 tanks. It can control two 120 VAC circuits independently (either can get turned on or off when the relay trips). Several amps for each circuit. It will be keeping a pump and UV from running if the water is too low for the pump to function properly.

Color code for the wires in the diagram:
black: hot
red: neutral
green: ground