Hi OPrime,
1. We dont get condensation on the tank
What temp do u intend to set for the tank? 20degrees? Highly doubt this will happen if the desired temp is ard 27/28.
2. Electricity consumption is lower
It's probably true only if u currently already switch on aircon during the day whether there's anyone home. Else not sure why will it be lower consumption??
3. The whole family benefits from the cool air besides our beloved fishy wishies and coral.
Sure, if the family is around the tank during the day. . Btw you can turn off the aircon at night when temp is cooler.
Just remember to switch it back on (Esp when u r not around)
4. No noise and heat emissions from the chiller
For a tank of ur size(7ft), use condenser with drop-in coil. Condenser can be placed somewhere outside like a balcony/patio, together with the other condensers.
These said, if ur tank/sump is not housed in a fullly enclosed cabinet, then ambient aircon would probably sound wise. Fans maybe required if using MH.
Question is: are you/family ready to deal with the stray lights and exposed equipment?
The idea of using a chiller/condenser/aircon is to keep water temp as constant as possible with minimal fluctuations. If you can enjoy the cool air while the fish/corals enjoy the cool water at the same time, why not?
Some food for thought... good luck in ur tank build. Read up reef central if you have some time, they have some really brilliant builds.