mh question

[cowdust9]

how high should i have 250w mh 20000k's over a tank that has about 12 inches from the top to the sand?

 

[musty baby]

High enough not to splash water on them (~8"). Higher if you've got anything that might get toasted by strong lighting. You can start out high and always move it down later.

 

[cowdust9]

and could i run the lights over the glass top or would they get to hot for that?

 

[musty baby]

You probably don't want to. The top will trap heat and kill oxygen exchange, and the glass may heat up to the point where water splashed on it will cause it to shatter.

 

[cowdust9]

oh ok thanks

 

[Double-J]

Ryan's correct. I would put the lights ~8" above the water line, The important part is you want the reflectors to be able to light the area they are above. So saying an exact number is hard to do, I would put them as low as you can while still being able to light the tank in all areas.

 

[BigHack2006]

i have my lights at least 18 inches awap from my corals, i have 2 400 watt MH, on a 46 bow. it might be that they got burned. i was in canada for a week and my dad was taking care of my tank and when i got back i had so much brown algee and my solinidy was over 3. everything came back exept my CAP and some zoos. i was wondering if they would ome back or not. i did have alot of zoos come ack though.

 

[musty baby]

18"? Every thought about trading someone for some 250s, running them closer to the water, not burning your corals, and saving $20 a month in lighting costs?