SuperColey1;38285 said:
Not overly sure what the 'grounded' malarky is as I am no electrician. lol
It is highly desirable to have the negative lead of a DC power supply at ground potential - connected to the ground terminal for the house wiring. This keeps the positive voltage at +whatever the power supply voltage is, rather than just that voltage above the negative terminal. (Or, that's what I've been told)
All mine are screwed in using the same screw as you and the heatsinks are well and truly touching the stars
Each LED is seperated though as the heatsink/LED combos are mounted on an acrylic sheet
This means your heatsinks can be electrically "hot", not a problem with low voltage circuits, but that would be a problem with my 48 volt circuit.
As for the moisture issue I think the 'splashguard' is the key thing. Will stop moisture coming into the unit, stop the fans creating more evaporation by cold air escaping downward, keeps all the fans cold air running through the luminaire, and as a 'just in case' I have my fans set to come on 15 minutes before the LEDs to dry out any moisture there may be in the unit.
I chose not to use a splash guard because it would obstruct the cooling air flow, which, for my unit, exits from the aquarium facing side of the fixture. And, since the fixture is about 5 inches above the aquarium, I can't see how moisture from the tank collects there - it is too well ventilated for that. (I think)
I was told never to wire high power LEDs in parallel, always to do them in series!!!
It isn't quite that simple, in my opinion. You need to wire them in series as much as you can, in order to keep the same current through each LED, but without having to supply a constant current driver for each LED, which would be extremely expensive. Then, the series strings can be wired in parallel, and the more of them in parallel the better, because then if one string stops working, the increase in current through the other strings isn't so big. I have only two strings in parallel, so the current through the remaining operating one doubles if one string quits. That forced me to keep the operating current below 500 mA for each string in order to stay below the 1000 mA maximum current allowed, in case one string quits operating. If I do this again I will use 12 volts DC instead of 48 volts, which will give me more options for wiring them, plus 12 volt supplies are much easier to find and generally cheaper.
A couple of threads I was using and getting good info/feedback from:
UK Aquatic Plant Society Forum • Login
Diy Whole Tank Led Lighting Retrofit - Tropical Fish Forums
On the strobing side of things, when I initially set mine up 6" above the water as the T5HO setup had been it sent my eyes 'wappy'. Its fine now it is 15" above the water much more like the 'glimmer/shimmer' of MH. One factor is the surface water movement I (and you) use. No surface disturbance removes the glimmer
AC
Thank you for the thoughts. Even when I don't go along with what is suggested, it stimulates me to think more broadly, and that helps a great deal in solving a troubleshooting problem. I would still be stuck, frustrated and sleeping poorly if not for the suggestions that have made it possible for me to figure out what was wrong and how to fix it.