Lighting in Layman's Terms?

i have a 44g with 2-250 mh's is this too much or is this enough to keep whatever i want its about 13.8 watts per gallon

 

WOW thats alot of light for a 44g. Thats what I have now and I have a 90g. IMO thats way too much light, maybe just one will do. What do you have in the tank now?

 

Im really glad to see us talking about par rather than things like watts per gallon. You cant go by watts per gallon as explained earlier in this thread.

Adam Blundell has a good article out with his version of how much par is needed to successfully sustain the different corals most of us have in our tanks.

Advanced Aquarist's Online Magazine - Lateral Lines: Classification and Terminology For Reef Aquarium Lighting

The Atlanta Reef Club has a quantum meter they pass around to members that want to see what the par readings are in their own tanks. I am including a link to the 3rd page in a great thread with pictures showing par readings in some of the club members tanks. This entire thread is very informative and is a great read with lots of pics all regarding the subject of measuring par with a Quantum meter. Pretty interesting.

Fun with the PAR meter - T5, Metal Halide and PC numbers - Page 3 - Atlanta Reef Club Forums

 

There is a time when lighting can reach a detrimental level to where oversaturation takes place... What this means is that corals that require light(symbiotic-housing zooxanthellae) can produce to much oxygen with increased light. So much light that the zooxanthellae can't produce enough energy to handle the intense light and with an overabundance of dissolved oxygen, in the corals tissue bleaching can result which ultimately can lead to the demise of the coral due to the zooxanthellae being disbursed by the host coral.
Having said this, there are many variables that, along with light, need to be addresed to ensure the best lighting and afford the light to actually reach the live stock dependent on the light.
DOM, turbidity, detritus, Gelbstoff, saltcreep, toxic mucus and chemicals as well as other variables need to be considered and monitored to allow the artificial light to reach the living organisms below.

Water flow, water quality, temperature, salinity and proper diet also need to be considered. I know that light is very important, but if your temperature is out of whack or shifts one way or another to quickly for instance, that will kill livestock faster than a subdued lighting arrangement.

Placement of your coral or clams is also a big part of determining if your symbiotic inhabitants are and can gather the beneficial light necessary to cary out photosynthesis.
This is it without getting to lengthy and technical...
hope this helps.