I know that light requirements are 4 to 10 watts per gallon, but is that necessary if the water is only 16 inches from surface to substrate, does water depth change the necessary light requirements ?
What are you wanting to keep in the tank? If you want SPS, you will need more light and exponentially more flow, if you want LPS and softies, you wont need as much light or flow. Also wattage isn't necessarily a good measure of how much light you are getting in your tank, LEDs use very little electricity and are extremely bright, whereas PCs use more watts for less light. Let us know what you have in your tank, or what your aspirations are and I'm sure one of the master reefers ;-) will chime in. Hope this helps!
sorry i wasn't very clear, what kind of critters do you want in the tank? if you just want softies, you should be fine with what you have, if you want sps or clams you will need to upgrade your lighting
Back when i first started my reef i ran a 96 watt PC fixture and thought hey this would be good enough for anything. I was wrong nothing colored up like it should have. the only thing i could really keep was zoos clove poylps very low light lps and a green hynophora. this was all in a 10 gallon. silly me though hey 9.6 watts a gallon i should be growing all kinds of stuff out of my tank. then i borrowed a par meter and really understood why PC fixtures were goin the way of the dodo as far as reefing goes. just an example dont let the watts per gallon fool you. i know have t-5's over my tank and now i truely have coral growing.
I have 8 T5s on my 40B and have been very happy with what I have been able to keep. I know someone that has 2 x 400W SE MHs with Lumenbright Reflectors and 6 x T5s (no reflectors on a 130 gallon tank. Very nice color & growth he has. You will get many different opinions when it comes to the subject of lighting. I would get many opinions and meet in the middle. I have observed accelerated growth with higher wattage MHs. I have seen many tanks and feel that 400W SE 20K bulbs grow corals very fast. High PAR value (like 250W SE 10K) without the loss of color. Also had a friend switch from 2 x 250W and 1 x 400W to 100% LEDs and he experienced a sudden alk depletion. And had to quickly recalculate is alk dosing requirements. He felt that his corals were growing at an accelerated rate with his new lights.
The Simple answer to this question would be as much as you can afford to put on it... The more light you can put on a tank the better. If you can only afford PCs then you will be limited to what you can put in a tank already. If you can go T5s then put as many as will go across the top of the tank. If you can grab up a metal halide or two these things will put out every thing you need. The old light per gallon thing was never accurate... I dont think I caught what size tank this is but put as much as you can on it. There are affordable fixtures that are cheap but will get you by from brands such as odesyea and coralife all the way up to the top notch giesman and so forth... just pick the best for you at the moment. And always pay attention to light needs of the corals you are buying... if it says best under T5 and or Halides they are speaking from experience. You dont find many PC lights anymore... I was like Whitney up there with my first... 30 long with PC lights.. I was able to keep LPS but nothing more... Read all you can in this hobby... The more you look at forums like this the more information you will absorb and the more you will succeed..
Well, until I can afford t5's I am sticking with t8's and plan on adding a few more, and only low to moderate light requiring critters, but I understand now that its not the total amount of wattage you have on you tank but the wattage of each individual bulb that matters. The higher watt the bulb the more intense the light is and the better it penetrate the water. Kinda like trying to get a tan from 1000 watts of normal light bulbs, its not gona happen, but get 1000 watts of the required intensity lighting and you will (per say). So if a critter has a high light requiremint 400 watts of t8's wont do, but 1 400 watt metal hallid will. Am I on the right page now?
Possible. But id like to add that on your tank id do as many t-5's that you can fit over it as you can. The Fish Tank carries a retro fit kit for T-5's its a 4 bulb kit with reflectors i cant remember how much it its but its not expensive. If you were to go with MH id probably stay in the 175 250 watt area. There is such thing as too much light. IMHO T-5's would do you just fine and you wouldnt have to worry about heat vs. MH. But if you want the shimmering effect you can always use LEDs to supplement this. A 400 MH would be best on a tank that are 24 inches and deeper. Also remember the higher you go on the Kelvin scale the higher wattage you will need for good growth. A 400watt MH at 20K will produce more growth than a 250 MH at 20K the difference is intensity. Most reef owner will run 175 or 250 watt MH @ 10K for growth with T-5 supplemental bulbs for coloration because most corals aren't that pretty at 10K. Better quality light along with good water quality will equal good growth.  Hope i didnt ramble I just enjoy talking about lighting.
