I had MH on my last tank, and ended up cooking it when I was out of town during a hot spell. Came back and all my corals were melted, and most fish and inverts were dead. I'm sticking with T5's... to be safe. From people that I've talked to, and setups that I've seen, you can grow pretty much anything under the right t5 set up anyways, so why pay the extra power and worry about the extra heat???

I have MH on my tank and love it I did try t5 but cant get the bright color with just t5 imo i do have t5 supplement with my MH to give more color pop
but like stated in previous posts the shimmer alone is worth it

thanks for the input guys. my biggest concern is heat in the summer as a chiller is a bit out of the budget. could running fans across the surface reduce heat from the lamps enought that i won't have to be worried about cooking my tank?

I have MH over my 125 gallon, and if I had to do it all over again, I'd get a nice T5 fixture instead. The multitude of light combinations, and the lack of heat issues are 2 major items that swing my vote for T5's. I know the shimmer is "nice", but I have seen too many amazing T5 setups that I wouldn't think twice about it if I had to do it all over again. You can get a nice effect by placing a powerhead close to the surface creating waves and ripples in the water giving you a nice effect, even with T5's. I do this even with my MH's.

Fans will help, but with 2 250 MH's, you'll need some good fans, and you'll likely hear them, and then you will also have a fair amount of evaporation, so will likely need an ATO to maintain good balance. I just went to an ATO this summer because of this.
So, you'd have the expense of the MH fixture, plus a chiller, or fans and an ATO. You could get a pretty nice 8 bulb T5 for that.

I just have a clip on desk fan on top of tank, that comes on when lights on, and off an hr after lights out. Keeps my tank pretty stable, maybe up to 82 MAX in summer. I'm also in a mobile home, so it gets pretty warm in there at times.

PS, I got 3 250W 2 DE and one SE

Should I ever go MH again (which I may very well do on the next tank) I will definetly have a chiller... I don't want to risk another catastrophic crash.

A fan will definitely help. I used to use a cheap $10 floor fan from Canadian tire and that kept my temp from going above 81. It was noisy as hell though. Ended up getting a sleek 4 fan unit that is pretty quiet. It plugs intou controller so it actually isn't on all the time. Controllers for the win here! When temp drops below 78 heater kicks in fan is off. When temp hits 81 fan kicks in. When temp is in a comfortable range neither fan nor heaters are on, so the temp in my tank never drops below 78 and never rises above 81 ever. I have 3 250watt halides :-)

I'd look into a combination of 1 & 2. Save up and get yourself a nice MH&T5 combo fixture and you'll get the best of both worlds. The good fixtures are made from aluminum and don't use fans which is nice because they control heat nicely and do not make any noise. You can also hang the fixture a little higher than T5 alone fixtures which will also help with heat. As a last resort you can always add a fan to blow air over the water and under the fixture which in my experience works really well on those hot days. My tank is easily kept below 80 in the summer with too small computer fans.

I'd stay clear from LEDs, although the technology is pretty cool you won't be happy with them. The intensity is too low and the color spectrum is too narrow, you will not get great coral color from such a light fixture. Well at least I've never seen a tank lit by LED show decent color in corals.

Laurier, I don't think you would have any heat issues to worry about if you had a fan on your cabinet next to the tank blowing underneath the lights. If anything we could probably use a fan up there in the summer anyways. :lol: