Looking for advice on heating tank with RKL

[neoh]

You should look into a 250W heater and just run the one. Better odds of something going wrong when you have two.

Also, it's best to keep the heater in the first stage of the sump where the water comes in as opposed to the return section, to allow more heat dispersment in a shorter amount of time.

The RK needs a the iTemp probe using the SL1 unit to operate. Assuming you use that.