OK, I have a 30 gallon aquarium that has a sump. I had no protection to prevent the tank from over following when the overflow sponge got to clogged. So I had to clean up about 10 gallons of water today.

I want to design a circuit that when a level switch goes low the pump turns off (I have this part down pat). My issue with the design (or where I am stumped) is once the level switch goes low I do not want the pump coming back on with out an acknowledgement of some sort.

Any thoughts will be appreciated.

The attached is what I have and it works if I did not want the acknowledgement.

 

I don't have an aquarium, so I'm not familiar with the setup or plumbing (and I don't know what an overflow sponge is). But I wondered why couldn't you use an overflow tube near the top edge of the tank? The principle would be the same as the overflow hole on your bathroom sink. The only requirement would be that the overflow tube be large enough to handle the flow from the pump.

The only technical challenge would be to drill a hole in the aquarium glass. I'd do it with some brass tubing and an abrasive slurry -- carborundum works, but diamond is faster (I'm assuming it's glass; if it's e.g. acrylic, then drilling the hole is simple with a standard drill). Once the hole was in place, a barbed feedthrough and some tubing running back to the sump would be all that's needed.

 

Attached is a picture of an overflow. Mine is like this only it was home made and cost 1/4th the price. In the picture (where the red box is) there is a sponge (it is a black very cores sponge, doesn’t pick up much) to prevent the fish from going in to the overflow and ultimately in to the sump where they could be sucked up in to the pump.

someonesdad:
To answer you comment that would be the easy way but the problem with it is my water level is always about 1/4 inch from the top and a 1/4 inch hole would not keep up with the 275 gallons per hour that is being cycled by the pump, and a hole any bigger would defeat the propose of the overflow. There for I need an electrical control to turn off the pump (just before the tank over fills).

 

OK, I think I have figured it out... I'll just use a S-R wired as so...

The text in the pic is backwords X4-1 is the pustbutton and X4-2 is the optical switch.
OH before I forget The optical switch is High in air and Low in water.

If some one nows a better way please suggest.