OK, the economics of this doesn't make sense. I've had both and there's no contest between a basement setup versus an under tank setup. Let's talk about the power savings first though, 100-200 watts continuous at $ .14 per kwh, is like $10-20 a month. For a reef tank, that just doesn't seem like it should be a factor but that's another argument alltogether. Do T5's instead of MH or use LED's for your sunrise/sunset cycle to be more green. Stock your tank with corals that don't need as much light and run your main lights less. Your basement is cooler in the summer, so you won't need a chiller, huge power savings there.
First of all, it's impossible to fit EVERYTHING under the tank. You'll still need a cabinet near the tank for items that aren't required to be "under" the tank. If you go basement, you can then fit all your food and ancillary items under the tank without having to stuff them in tiny hiding places.
Then, there's the issue of water damage from normal maintenance, accidents, salt on the floor and walls, possibly even into an electrical outlet causing a short and a fire, like what happened at my orthodontists office. Due to the cramped space, you might bump a fitting, move something accidenally, not notice and you will have a disaster that doesn't just take down your tank, but possibly your living room too! I once had a GFCI trip in my under tank setup and the GFCI outlets were tucket up underneath at a place where my parents couldn't see them. This caused my ATO pump to not work and they didn't notice until the sucking sound in my sump from the main return pump. They had to go to my house every day to manually add RODI until I got home from my business trip, instead of the every 2-3 days I told them they needed to go there. I was on the phone with them trying to get them to troubleshoot it with me and I told them to push the button on the outlet with the light on, but they were too old to bend down enough to see it, tucked up underneath. Had that happened in the basement, it probably wouldn't have happened because it was caused by salt mist, but anyways, they would have been able to find the outlet and reset it.
I've had both and the basement sump and "lab" setup as you call it is infinitely better. You work standing instead of crouching. You have a utility sink nearby to clean your gear and dump waste. A BIG thing that guys may not notice, but a woman's sense of smell tends to be much more sensitive, is that my wife can smell my skimmer, algae, or other organic waste the 2nd it touches the air. I have to practically put my nose in it.
The main problem I had was that it was just really tough to clean the skimmer. I actually clean pull my skimmer out every 2 weeks and clean the neck, under the tank, I probably wouldn't ever do that, it's too messy.
I could probably list a plethora of more reasons I prefer it, but I just wanted to chime in and raise the argument that if you can do a basement setup or a "fish room", do it. Somebody please tell me some good reasons not too.
