MH Heat & wattage ?

Will 300 watts of 20k metal halide but out less heat than MH 20k 500 watts?

 

I think the more wattage, the more heat. The K rated also has to be considered.

 

Yes but not so much as to really notice it .. I am not sure where you will find this wattage of aquarium bulbs .. If you can keep the water running say 250's then you would have little more trouble with cooling from a 400.

 

So with 2 150watt MH's on each end of a 75
gallon tank theres a good chance of needing
a chiller as with 2 250watt mh's ? Ill have
fans on each end of the Xtra tall canopy...

 

150's on a 75 is about as useful as teats on a bull 75 is rather deep to get enough light to the very bottom. And if you want to keep Clams and some corals on the very bottom you will not have the power 175's would not be much better either. I myself would go with the 250's As for cooling it ? if you keep the room the aquarium will be in cool and use fans with enough CFM's and not little 12 Dc computer fans and add one like a clip on over the sump then you maybe will be fine But again that depends on fan type and room temps and the amount of water you can evaporate.. And the humidity level of the room will effect that also. But as I said on a 75 the 150's will be Weak at best and if you supply good VHO actinic then you can reduce the hrs a day you have to run the M/H's We run 3 400's on a 180 and I have never found need of a chiller here or on any home tank as of yet..

Also the fans can and will be effected by the hood design I leave all of my hoods totaly open in the back and I push in and pull out the air from oppsite ends of the hood..

 

Tangster, if i put 600 watts of MH and T5 would that be enuff for clams ect in a 75 gallon or 90gal?

 

I have a 90g with 692 watts(MH and actinics) over it and I have just about everything.

 

i have 500watts of MH over a 55gallon. No need for chiller yet. I have my cabnopy suspended over tank with back open. 1 fan on each side blowing in. They kick @$$

 

Lunatik....do u need a chiller?

 

Never had the need for one. Between my a/c at 73 deg. and a fan(at times) my temp. is always around 77-79. Placing fans to blow across the top of the tank and one at the sump/wetdry will do wonders. In fact, I recently had to buy a heater to stablize the temp. First time in 15 yrs that I had to buy a heater. As long as you let your display tank breath and maybe a fan you should be ok. The only draw back to the fans is that your going to top off more freqently b/c of evaporation.