They will leak and fry themselves.
I used two of the El Sid solar circulation pumps and both died after about 3 years. The o-ring starts leaking and then the electronics get wet and fry. If I were to ever get the El sid again (which I will not) I would put some RTV high temp silicon between the impeller housing and the stainless cover plate around the O-ring area to treat it like a more permanent seal. Other then having the pump leak and then kill itself, it worked well and was very quiet. I gave it a bad rating because one want something like this to be very reliable.
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