i'm looking into getting a MH for my 72g tank but before i buy one, i'd like to know as much as i can about them so i can get the right one. anyone know where a good place to find MH info? also, what is HQI for a MH light?
HQI is a Double Ended Bulb. It gives off more bright light. But I would Suggest looking at the 250watt Mogel with 2 110watt VHO's That is what I have on my 72 gal Bowfront The growth rate is tremendis. I have no complaint's on my lights. here is a link to the page were you can find it. http://marinedepot.com/md_showCart.asp? ... sp?CartId=. It may show you the price that did for you but you can always stay with the 175 watter it is up to you. whatever light you go with you will be happy MH's are the best way to go.
Without disagreeing with Reefguy, as he's given sound advice. I have another perspective.
I would go with a 250 HQI. It's brighter than a 250 mogul, and will be able to put ANYTHING in the tank without ever wondering if you have enough light for growth. To be able to say this about a mogul, you have to go with 400 watters.
The disadvantage is it will cost a bit more. Figure about $400 for a fixture ready to roll. If you're a DIY kind of guy, you can do it for less. The ready made fixtures though are NICE! The color of your corals will look a bit better if you suppliment with an actinic though.
this might soudn stupid, but would a MH system melt the plastic on my glass top. i have this 'all glass' glass flip top so if i put a MH lamp over it, would it melt it?
When running these systems, you generally have to do away with your top. This is because a layer of hot air will develope between the water and glass top, this will overheat your tank in short order. Acrylic covers will get hot and warp.
YOu need the top to be at least partially open, and the fixture needs to be 11" or so above the tank normaly.
I agree with JimM you don't want your MH to close to the water. I actually keep mine about 6" from the top and have no problem but I have no hood or Canpy. Now to answer your Question about the MH175 with the 48" Antinic that would be good if you have a Canopy. but you want to get as much watts as you can so if you can afford 250 or 400 go for it.
The heat generated will serious warp the plastic hinge of your glass top. You will have to remove the glass top entirely. Besides, even if you place MH lamps high enough and don't remove the glass top. Salt will accumulate under the glass and block the light penetration.