2 x 400 watt mh on my 150 gal, how many fans???

[JMR99]

Hey guys, any Ideas on how many fans I should run on my 150gal with 2 mh 400watt, I want to go without a chiller, blowing in or out?? hopefully something quiet, many thanks in advance, Jose.....

[reefkrazy]

I got two on my fixture. one blowing cool air in and one blowing hot air out. The cool air runs along the bulbs.

[JMR99]

Thank you!!!!

[MSHUR]

I use to have 2 in and 2 out and i still had to run chiller...

[reefkrazy]

so far no chiller yet. Im running over a 1,000 watts of lighting over my 90g. I have my lights suspended, so I can raise ir lower it to disapate the heat. I did notice that 400w does kick off heat at about 8" from the bottom of the fixture.

[Wrench]

I have two 6" clip on fans inside my canopy. Both blow across the top of the water.

[God of thunder]

Are you planing to have the canopy open?

[JMR99]

No , but I guess I can cut the back to make it open or put a fan out the back together with the other two side fans. What do you think?

[bubbletip2]

I have 4 fans on my 156g(5ft long) and have kept my temp within 1 degree from 78.5 to 79.5 all thanks to the Reefkeeper 2. I would highly recommend the RK2 for temperature control when using fans. It only turns on the fans when you tell it to. For me when my temp gets up to 79 the first two fans go on and won't go off until it is 78.5. The next 2 fans go on at 79.2 and will go off when the tank is at 78.8. Some days only the first 2 fans run even when the lights are on. Other days all fans run when the lights are on but will turn off a half hour after the lights go out.

Without the RK2 basically people set the timer the same as their lights. The problem here is the temp will go up to a level overnight that consequently after the lights come on, the tank can get up to 83 degrees. With an RK2, when the temp goes up a bit at night the first two fans come on usually every couple hours to bring everything down to 78.5. On summer days you will still ned to make sure your AC is on otherwise no amount of fans will stop the temp from getting to high. I was told with 2 400w bulbs that a chiller was definitely needed. Not if you have an RK2;)

[God of thunder]

What i did was leave the canopy open at the top and got ceiling fan over tank, that worked really well for me anyway.

[JMR99]

Thanks guys, I'll look into the rf2's......

[chk4tix]

When I had 2 400w mh on my 120g, I only had 3 computer fans in the open hood and it kept temps under control

[dhnguyen]

I have 2 400W over my 125g and I don't need a fan. Granted I don't live in FL.

[bubbletip2]

Best thing to do here is run your lights for a day without fans and see what the temp goes up to. If it does not go to high than great. If it goes too high then I guess you have to decide if you can live with large temp swings. If you want to keep things within a degree or two, then a chiller or the RK2 option is the only methods I konw of.