MH and temp.

[ducati24]

Hi guys, I am new to the hoby and setting up my first fish tank in about a week and a half. I am starting with a 75g tank and a 20 gallon sump and about 70lbs of live rock.

I saw metal halide bulbs in person for the first time today, (I had to drive 50 minutes to do it) and I think I have to have one! The setups I saw where at various wavelengths and were all 175w fixtures. The guy at the fish store said that My tank is going to get way to hot with this setup.

Is there any way that I can fix this, aside from an air-conditioner or a chiller? O yeah and the bulb will be about 9 inches from the water and I live in NH. In the summertime it is usually mid-70's but we have days that reach 95 every once and a while. The tank is in the coolest room of the house.

thanks a bunch
-ducati24

[Sebastian]

I have twin 10k 250 watt mh on my 75. temps get a little high (85+) at times but if i open the doors on the stand and run a fan blowing over the sump it cools back down to acceptable levels. I have three small CPU fans in the canopy as well.

[rtrice1]

I think it really depends on what temp. you want to maintain in the tank. Adding 2 to 3, four inch fans in your canopy that blow directly on the water will help keep your temps in the mid 80s in the summer. Be prepared to have an auto-top off system (water evaporates fast using this method). I'm using two 250W MH with two 5" fans in the canopy on my 90gal. I prefer to keep my tank at 77degrees. I decided to invest in a chiller just for peace of mind during the summer months.

[ducati24]

Thanks Guys,

so you think with a single 175w MH I would be fine with just fans in the hood right, it is completely open in the back?

[rtrice1]

You should be fine tempature wise with only one 175W. Although, with a 96W actinic, you will only be running about 3.5W per gallon. You will need more wattage if you want to have LPS or SPS corals. You may want to consider two 175W bulbs.

[ducati24]

Thanks, one more question, if I have a center brace in the middle of my tank, what do you think the best spot for the Halide would be?

[rtrice1]

Hmmm.... more reason to use 2 bulbs. If you decide to go with only one bulb, make sure to use a spider reflector and try to position it close to the center brace but not over it. The spider reflector will help dispurse the light throughout the tank.

[Scuba_Dave]

I have twin 250's on a 60g hex. 2nd 250 is for high noon. Since I am not home in the day I leave the front door of hood off. Temp stays at about 80. Fans would accomplish the same thing. If I put door on Temp goes up to 83. Before summer sets in I will add fan(s)