# DIY Auto Topoff



## jmatkowsky (Nov 22, 2012)

*DIY ATO (Auto Top off) for $25*

I had some time at lunch so I figured I'd sketch out how to make a DIY ATO for under $25.

These are the parts needed and can all be bought from Aliexpress.com which includes free shipping and no duties or taxes. Will take 2 - 3 weeks to get all the parts. See diagram for details. I'm terrible at drawing so my apologies for the ghetto hieroglyphics.

The basic idea is that a relay acts as a switch and controls the live connection of a power cord (120v). When 12v power is applied to the switch, the switch is engaged (open) and a live connection is made, passing power to the socket (120v). When the 12v power is cut off, the relay closes the switch and power is cut to the socket. A 12v adapter is spliced so the live (red) cable is connected to a series of floats. Depending on if the float is up or down, 12v power will be passed along (or not) to the relay. This is how 120v power turns on to control the pump. If you put a series of floats, 1,2 or 3, you can have them each do something to control the power. If using 3, the first in the series should be for cutting power when the water in the top off tank drops below a certain level so your pump doesn't run dry. The 2nd float will act as a backup and will cut the power if the the water in the sump goes above a certain level- to prevent the pump from running if the 3rd float switch is stuck for some reason. Then the 3rd float is to pass power when the water in the sump drops below a certain level and once the water water pushes the float back up, it will cut power. Float 2 should be an inch or 2 above float 3. Float 1 should have it's float reversed. You can remove the white float by taking off the small half circle disc at the end and reverse the float. This way, it will close the switch/cut power when the float is down (and your top off tank drops below a certain level).

1 x 12V Relay switch with base ($6.50)

http://www.aliexpress.com/item/12V-...N-5A-With-PYF08A-Socket-Base/32230878151.html

1 x 12V power adapter ($4)
http://www.aliexpress.com/item/New-...or-DC-12V-2A-24W-Power-Supply/2051934100.html

2 - 3x float switches ($ 5.50)
http://www.aliexpress.com/item/New-...zontal-Float-Switch-3-Pcs-Lot/1527985138.html

1 x Junction Box ($5.50)
http://www.aliexpress.com/item/FREE...lack-10-3x6-4x4cm-Waterproof/32234734917.html

1 x power cord ($2) From dollar store

1 x power switch (not necessary) ($1)
http://www.aliexpress.com/item/1PCS...SPST-Switch-Round-Rocker-For/32246770357.html

1 x led indicator light to show when pump is running (not necessary) ($0.50)
http://www.aliexpress.com/item/AD16...r-Pilot-Lamp-DC-12V-20mA-New/32260279649.html

1 pack of suction cups for floats ($1.75)
http://www.aliexpress.com/item/Whol...ne-Tube-Holders-Clips-Clamps/32255847498.html

2 - 3 meters of wire ($1.50)
http://www.aliexpress.com/item/Dual...red-and-black-cable-and-wire/32294267000.html

You can use any pump- small powerhead(if not too much lift/head pressure), or the one i have (Tom Aqualifter). ($18 on amazon) 
http://www.amazon.ca/Aquarium-Aqua-L...om+aqua+lifter

I had a JBJ Auto top off, but it died as i had it hidden under my cabinet where my sump is. The electronics don't like the humidity because it actually has a pcb board that goes finicky with humidity. Plus, it would shut off my Tom Aqualifter pump after 1-2 minutes even before it got a chance to top off the water and reset the float. When the float isn't reset, it doesn work. And, you can only have 2 float switches.

This DIY has a Electromagnetic switch so no electronics to get messed up by humidity and its more durable IMO.

Anywhoo, it was a cool project and i'm happy with the results. It works alot better than the store bought one.

Cheers!


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