no way would it be excessive. You can put your heaters in the sump as well as if you have hang on filters you can hang them on your sump instead to have a less cluttered main tank.
sumps ease water changes in that you can just shut off the pump. drain the water from the sump. Add new water to the sump to the same water line the sump had before you drained it and then power up the pump. water change done.
I would suggest something larger than 10 gal
. The reason is evaporation. You can expect up to 1 gal
of evap per day from a sump setup on a 55 gal
. You cant run the sump at full capacity (10 gal
of water) because you must provide some room for backflow when the pump is off as water will flow out of the tank to some degree into the sump. This means your sump will most likly run with a max of 5-6 gal
of water in it. Since most pumps pickup above the bottom of the tank a few inches this gives you something like 3 gal
of acutal evaporation room. (the pumps used to return water will cause a vortex kind of action when the water level is close to their inlet so water must be an inch or more above the inlet to keep air from being injected into the system).
This would give you at max 3 days between topoffs of the sump. If you upgrade to say a 15 or 20 gal
tub for the sump you can get up to a week between having to add additional freshwater to the system to replentish evaporation.
You cant put a wet/dry filter in the sump but the wet/dry filter itself is a kind of sump. The wet part of the filter is the sump and the dry part where the water trickles over the bioballs is the filtration.
The skimmer will not work on freshwater so there is no need.