Well I dont know about cheap I have a lot of money put into my reef tank but it honeslty made my room so hot that I couldnt sleep in it. So I went with the hypothesis that a large surface area pool with a circular shape would be easier to control (flow wise) and theres only two clowns in the tank so nutrients are crazy low. Plus with the shallow depth of the pool (8 inches) I only needed one of my two 250 watt MH's.
Anyways the hypothesis worked, with one Koralia pump the flow is perfect in the pool and the coral polyps are extended greatly. As for the 75 in my room theres almost no heat now. And I can finally sleep in my room lol.