The reason I set up a frag tank was because I had the perfect spot for it and it's a very handy place to feed the suncorals. I have it set up on the top of the power station, and it is tied into the 400g's sump. Heating, cooling, skimming, biopellets, carbon and a calcium reactor maintain water quality, and an Vortech MP10 provides the flow.
My frag tank is 22" x 13" x 8" with a 1" Durso drain in a 5" x 5" corner overflow. The locline feeding into the frag tank is adorable, I've never seen such tiny locline before. It's got a 1/4" outlet. The tank holds just under 10g of water.
Using sliced Marco Rock, I decorated the tank with a solid surface to place corals in the bottom and siliconed a few pieces to the back and right wall to hide what would otherwise be seen through the clear 3/8" acrylic. The tank is being lit with Reefkoi's Evolution LED fixture, Generation 3 I believe. With the whites and blues on, it's in the 14,000K range.
This tank is situated at the end of the 400g tank under the external overflow. Water is being pumped into it from a manifold off the sump, so all of its filtration & dosing needs are cared for. All I do is feed it and enjoy.