[mike31154]

Thanx, it's been running well since last April. Last week I finally did some additional current measurements. Been meaning to do this for some time since the only other time I measured current was before assembly. Constant voltage is not the conventional way of running a LED fixture & doing so has its risks, but I've seen instances of folks cooking their LEDs with constant current drivers as well.

At any rate, the current measurements taken at several different forward voltages revealed that I've really been underdriving the fixture. Highest I've had the voltage is around 9.5 volts which is 0.5 volts above the lowest recommended voltage for the Royal Blue LEDs. That was only for a short burst though & since putting the fixture in service I've kept the voltage at about 7.5 max.

There was a definite difference in current between a Blue & a Royal Blue at 8.5 volts, with the Blue drawing 310 mA & the Royal Blue drawing 500 mA. Both numbers are well below the 1,000 & 900 mA rated current. It took 10 volts to get the Blue up to 500 mA. By comparison, a 10,000K white was only drawing 180mA at 8 volts. Need to keep in mind that the voltage/current curve is not linear & current rises quickly once you get close to the maximum forward voltage. One of the reasons I've kept the voltages fairly low up to now.

Only checked one or two of each colour LED so I need to do more measurements to compare the current difference between LEDs of same colour at the same voltage in order to see how well (or not) balanced things are. After running for months, they have to be 'burned in' & there should be no surprises, but with electronics you never know. They're well cooled with the individual fans now running at 10 volts, so I'm reasonably confident that there should be no major disaster even if one or two burn out & I don't notice for a while.

Even at the 6 to 7 volts I've been running the LEDs at, coral growth was very good, comparable to my previous Halide/T5HO set up. Since taking the current measurements recently, I've bumped up the voltage of each colour to 8.5 and the tank looks great. Quite a bit brighter, especially the whites, so I'll need to keep an eye on things to ensure I'm not burning coral. Looks good so far after several weeks & algae is not getting out of hand either. Could probably run them all at 9 volts, which is recommended minimum forward voltage for all colours except the 10,000K whites (10 volts), but there seems no need to do that based on growth & look of the tank. Besides, that would use more power & probably shorten the life of the LEDs somewhat.