I have a pizeo beeping alarm wired to my main bilge pump so I hear it anytime it goes off.

I have a second float switch placed about a foot above the pump float switch (deep sump) wired to a pizeo alarm with a continuous tone.

Beeping for a short time I make a mental note. Frequent repetition or a long time beeping would alert me to a problem.

Continuous tone is an alarm I have never head except in test mode. The float switch I use for that one is a kind that I can trigger by raising a glass of water up from under the sensor.