Instead of a float type switch--which was too big--I tried the Johnson Ultima electronic switch; it works great. It has two sensors that detect [any kind of} water and a delay so it only goes on if water is there for sure, not just sloshing around.
[The round RULE 800-GPH pump] pumps the water very quickly and shuts right off until the sensors get covered again. This is very easy on the battery. I have never found the battery dead even after extended downpours.
I added a small shim under the switch so it would be slightly above the pump intake. The Ultima switch is so slim I can still get at the drain plug easily if need be.
What I read about the [Johnson Ultima electronic] switch was that it is not as waterproof as older models, so I coated the wire leads where they went into the housing grommet as well as the seam around the switch housing with plenty of neoprene liquid electric tape. That seems to have worked because I have not had any problems in two seasons.
What I do notice is that water left in the sump for an extended time will start to grow stuff on the sensors, hold water, and trigger them. The solution is to wipe them off once in a while. I am very happy with this set up.
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