I've just used motion detector lights - those seem to keep varmints at bay.

Sounds like a raccoon. The "blast" is what works. A sprinkle won't do anything. Can you point the unit away from the side of your house?

Or fence in the pots with some wire fencing.

two nights ago, I gathered all the pot together and put wire fencing around them. so far, the critter has not been back to do it's "dirty" work!

We have been using an electronic deterrent - it makes some kind of noise - sort of like a dog whistle - and blinking lights. It does seem to keep raccoons out of the fountains, but it does nothing to deter squirrels or possums. I'm going to put wire fencing around my pitaya to protect my fruit from possums.