What do you mean? Is it a heat issue on the tank or something else. Im a newbie and this is the lights that came with my setup. So upgrading wont be that bad as long as i do it one time. I do agree with you thou and i should use these for awhile to get a comparison when i do upgrade.
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I don;t understand the statement that you do do not want to use T-5's on a tank this size either. The only think I can think of is they may be considering that you may want to use LED's in the future. But after working with both I find that mixing T-5's and LED's can give you the best of both Worlds.
If your considering a gradual upgrade then I would stay with your present T-5's initialy. The 2 4 bulb fixtures at 39 watts each would be good starting point for many LPS corals at mid levels in your tank. Then in the future you can add additional lighting either LED or T-5's.
If it were my tank I would run LED's in a DIY set up for predawn to post dusk using 430nm, 454, and 460 nm LED's in equal proportion. This would give a deep blue effect which would make the florescense pop well beyound what they would with any T-5 lighting.
Then you can use your T-5's for a dawn to dusk effect running mostly Blue Plus bulbs that would not only brighten up the tank but also fill in the gaps that are lacking with a Blue Plus set up. Initialy you may want to add a corl plus or two on each side to add more lighting untill you add the mid day lighting.
For mid day you can either add 2 T-5's on each side or run another strip of LED's. With the midday LEd's this will depend a lot on your color preference. But you have the option of adjusting the LED ratio to meet your personal tastes. Neutral White will brighten the tank quickly, Cool Whites will retain a blueish tone, and 454 nm royal blues will add more usable light for the corals. I like the effect of a 50/50 ratio for midday between the royal blues and neutral whites.
The watts per gallon can be very misleading. I initialy had 1,000 watts of 20,000K XM MH's, plus 220 Watts atinic Compacts for a total of 1,220 watts on a 120 gallon tank. When I switched to T-5's 432 watts my tank looked brighter lite than before and I only lost a little of the blue light the coral love. On another smaller tank I went from 156 Watts of T-5's 2 blue plus, 1 Purple plus and 1 Aqua blue plus to 60 Watts of LEd's and the tank is brighter and the florescents is crisper than the T-5's were. Coral growth is slightly slower however than with the T-5's.
So if your looking a Watts per gallon here you have a range of roughly 10 with the MH's and down to 3.6 with T-5's and 1.5 with the LED's. You will get better coral growth with the T-5's but you cannot beat the florescent colors of the LED's. As I want both I suggest mixing the T-5's and LED's.