This is biggest problem I have in the whole hobby, figuring out what light fixure to use. Are there any ways besides using reccomended wattages to guage what lights you need/ I've notticed when looking around the forums that it is a general agreemet that this is not a good way to go about it. Other ways are mentioned, but not normally in any detail. Are there any reliable methods besides guess and check?

First what are you wanting to keep?
Second what size is the tank and how deep?

I would not use anything less than PC (power compact)lighting, that is the min. IMO
next in line ( if I remember ) is VHO t5 fluorescent. then MH.
Most people use a mix of lighting. I use PC and am working on adding a 70 watt hqi MH to my setup.

If you give us your tank dimensions L x W x H and an Idea of what corals you would like to keep Im sure a few people here will give you some good info

I just spent 6 months and visited a lot of other reefers tanks, before I purchased mine. I feel that besides husbandry your skimmer and your lights are most important items that lead to successful reef keeping. Once you answer steves ?s we will be able to give suggestions of what types of lights, fixtures and even bulbs might best fit your reef.

Right now I don't have a plan for a new tank to up. This is really more of a general question. what is the best way to guage what type of lights you need?

depending on what you want to keep in your aquarium. you can go with cheap florecents for a fish only tank, or you can go with the expensive metal halides if you want a reef tank. so it really depends.

Say you want to keep the corals or anemones with the highest lightest requirements. Is there a rule of thumb somewhere?

Say you want to keep the corals or anemones with the highest lightest requirements. Is there a rule of thumb somewhere?

For the highest light requirements you are looking at MH with maybe atinic PC
If I remember corectly one MH bulb can lumiate a foot print of 3' so for a 6' tank you would need two MH lamps

The depth of the tank would dictate the wattage of the lamps ( the deep the tank the higher the watts needed for the lighting to get to the bottom of the tank I think I cannot remember at what depth the watts need to change.

I could be way off here so Please any MH people out there feel free to enlighten me;)

If you are into reading here is a link to Sanjay's lighting site. http://www.reeflightinginfo.arvixe.com/index.htm He is very knowledgeable of lighting.

I have 2 250 MH over a 48 inch 75 gallon tank. We ran that way for a year or so and then added 2 actinic VHO's and we still want 2 more VHOs. I think if I had to do it again I would go for T5's IMO.

currently i have a 55g 48x12x22, like i said before for highest lighting requirements what would I need?

Depending of what type of light appeals to you. You can be safe with 2 150 MHs and 2 96w PC for atinics. If you like the real blue look you can have 20k MH and Actinics, or if your looking for growth then 10k with actinics. If hou didn't carefor metal halides then go with T5s and alternate the 10ks with the actinics, but have had no experience with them. I had gotten away with PC over a 55gal before, but the more I added I began to struggle with the temp. Plus, the tank isn't that deep so you don't want to cover the whole top with lights do you? I personally would go with MH and PC combination if I were to do a 55, infact I may just turn my old 55gal into a frag tank.

Currently this is a freshwater tank just barely getting along (live plants are growing alot) with just 32 watts of the lighting that came with the tank. If I did change this to a reef tank, would the oddysea 36" 305 W be good?
http://www.aquatraders.com/index.asp?PageAction=VIEWPROD&ProdID=277

I have an Odyssea PC light and it is OK. The fans are a little noisy but I only hear them when my return pump is off. :) The biggest drawback is that mine has 2 switches but only one cord so you can't use both the PC and moon lights with a timer. I just don't use the moon lights so I can keep my photo period regular.