lighting for corals

I am new to corals. When I look at the requirements for different corals the lighing says low, moderate, high. What lighting is considered low, moderate,or high. thank you

 

high = metal halides or very close to t5s
moderate = t5s pcs or middle to bottom of tank for halides
low = some what shaded not in direct light.

this is my opinion and when buying coral ask about each coral and you might have to play with lighting. some high light coral will only do good under halides also.

 

i like this answer just gonna add when you get more comfortable with the lighting you can play around with the wattage to get different areas. i would say acrewoods recommendations are assuming you have the standard 4 watts per gallon of lighting.

 

I have 2 65 watt flourescent and 2 65 watt actinic and these are mid...for soft corals only....

 

I have a 20 gallon tank 1 65 watt flourescent and 1 65 watt actinic. Should I assume that would be considered low lighting?

 

i would consider it moderate since the tank probably is what 12 inches deep. you have 6wpg of compact flourescent. you should be able keep most soft corals and a few lps.

 

The low, moderate and high lighting requirements vary and will be a characteristic that varies based on a number of variables. Height of the tank, height of the lights above the water surface, type of lights, turbidity and species of coral. By taking these variables into consideration, you can then better determine the amount of light you have.
Many coral species will acclimate themselves to either higher or lower lighting over time, however the coloration may differ somewhat from other lighting schemes, as well as spectrum kelvin output.
The idea of watts per gallon should not be taken as "etched in stone"! Don't get trapped in that whole thing...
Factors such as turbidity, dissolved organics and particulates, water parameter issues and placement of your corals within the tank will have a profound impact on the PAR and PUR(which are more appropriate measurements of light amount) reaching your livestock below.
Hope this helps somewhat without getting too lengthy or technical....

 

i was trying to give a generic answer as to really getting in depth. but yes I was shooting for 4 watts per gal. and an average tank. nothing deeper then 16 in. I even with corals I know still play with placement and trying to get the best growth and color.

 

Just keep in mind wpg is a very general general guideline. If you have a 200 gallon tank and you only put a 250watt metal halide over one end of it, you only have like 1.25 wpg but you could keep almost anything you wanted as long as it was under that lamp. Seems obvious but just pointing out that wpg is just a general guideline.
I agree mostly with what 10acrewoods said although I think with power compacts you might need to keep moderate corals higher up (depending how deep your tank is of course) as they don't get the same penetration as T5's do, also T5's will keep just about anything you want, they are the best option in my opinion.

 

Another thing to take into consideration when lighting a tank is the depth. Light can dissapate and rarefract the deeper you go so put the depth of the tank into mind.