I am getting ready to set up a custom 60"x27" 18" deep mixed reef tank, more sps than lps. Have been in the hobby for several years but have no experience with T5 lighting. I have several questions related to lighting and I realize these questions have been asked before but in different threads.
1. For a 60" tank should I get a 60" or 48" light?
2. How many bulbs?
3. What combination of bulb? I light bluer and more purple. Would also like an actinic bulb.
4. I am planning on adding a reef brite LED. Which LED and what is the schedule to run?
5. How high off the water should it hang?
Thanks in advance for your input.
1. A 48" light will cover 60" tank length with no issues. You will have slightly less par on the ends, though. Most people tend to leave room from the tank glass anyway, so I tend to favor using a fixture that is 12" (or less) shorter than the tank length. The other reason I favor using a shorter fixture is that I prefer to mount my fixtures 12" or higher. This just gives me more room to operate / maneuver without worrying about the light being in my way. Also, higher mounting height means less salt spray and splashes getting on the acrylic shield. Higher mounting height gives great uniform spread, but T5s are already so good in that area, that that is probably more a consideration for high powered LEDs that may create hot spots.
If you like the idea of dimmable T5, you will need to go with 48" as that us not an option with 80 watt (5 foot bulbs). I don't think you need a dimmable fuxture, but some people like that.
By the way, perfectly fine doing the 60" fixture also. You would probably just need to mount it a bit lower. T5 reflectors tend to push the lightly mostly straight down, but you might get some light spill depending on your mounting height. I'm guessing you'd want a 60" fixture mounted 8 inches or less unless light spill doesn't bother you. But I'm guessing on the mounting height as I always go with the smaller fixture route.
2. My rule of thumb is 1 bulb per 3 to 4 inches of width. For led / t5 hybrid, one bulb every 6 inches. If your tank is 27" front to back, then I'd go with an 8 bulb unit for sure, unless you know you know you do not ever plan on keeping high light corals or clams. You said you will have SPS, so I think 8 bulbs is the way to go. This will give you more than enough light for anything you want and even if you dud the 48" light fixture mounted at 12" or higher, the 8 bulbs would be great. Plus, having 8 bulbs just allows you to really fine tune your preferred bulb combination. And if you use an ATI fixture, you can choose to run just the 6 bulb channel most of the time if you don't need the extra par from all 7 bulbs.
3. Tons of bulb combinations. You will probably need to buy a few and try out combinations. Plan on 5 to 6 blue type bulbs (blue plus or pure actinic) and 2 or 3 full spectrum bulbs. Since you said you like bluer type tanks, I'd probably recommend 5 blue plus bulbs, 1 pure actinic bulb, 1 purple plus bulb, and one coral plus bulb. That's a combination that should get you pretty close to what you're wanting and you will have 4 types of bulbs, so you should e able to gauge what you like about each and what you might want more or less of. For instance, I never run a purple plus bulb in a 4 bulb or 6 bulb setup, as i find it a bit too much for my tastes aesthetically. In an 8 bulb setup, I think it would work great. Some people love the bulb and might run an additional one instead if the coral plus for instance. In my case, I'd be more inclined to run 2 coral plus before I'd ever do 2 purple plus. It's just going to come down to personal preference. If you need a whiter setup, you can swap in another coral plus for a blue plus bulb.
4. The T5 fixture will provide you plenty of par and full spectrum from your bulb choices. I usually recommend people go with the deep blue / actinic type LED bars with their T5 fixtures. LEDs do such a great job in that deep blue look, and I think they are better at dawn / dusk applications. They can provide that extra pop people like better than even the T5 pure actinic bulbs also. Thus, I'd rather use my LEDs for deep blue and pop and free me up to use more full spectrum bulbs like a coral plus bulb in my T5 fixture.
If you are really, really, really ultra sensitive to tank color and want to be able to fine tune your tank color to the nth degree visually, then you will want an led bar that has some white and blue diodes in it. Honestly, though, with 8 bulbs of T5, you should get to an overall color you like by swapping out various bulbs for others.
5.
For a 48" 8 bulb fixture- mounting height of 12" or as high as 15" if your tank is going to only be 18" depth. Note, I mount my fixture 16" high but it is inside a floating canopy and I have a lot of LED supplementing the T5 so the loss of par isn't an issue for me.
For a 60" fixture, a mounting height" of 8" or higher / lower depending on your tolerance for light spill on the sides.
Hope that helps!
