mr.wilson
.Registered Member
IMHO, it's real world experience vs theoretical. It's nice to assume that things run at 100% but we all know that it doesn't.
What generally reduces bulb lifespan is the "vacuum" loss/O2 infiltration/filament/gas impurities and eventually Hg oxidation deposits at the ends, which in essence means less Hg gas/"dirty filament" to excite for UV emission for phosphor excitation.
Dimming of bulbs just means that there is less current available to the filament to excite the Hg gas in the bulb envelope. Taking into account of aforementioned real world physicalities, what I remember in my spectrometry courses (I have the txt but not enough time to double check and reference), the sputtering effect (dimmed vs 100%) is what causes the low life span of dimmed bulbs.
I'm sure that they can make a more "ideal" bulb but it's not going to be cost effective for the aquarium industry.
JM2C
I don't understand most of what you said, but I understand what you are saying


I'm not sure how short 0-10v dimming T5 ballasts fall short, but between reliability and bulb life, it looks like we will pass and use LED PAR 38 moonlights. It means a bit more wires and clutter, but it's manageable and at this point in time, a best practice.
Some manufacturers put LED lunar lights onboard MHL fixtures, but they run the risk of being overheated by the MHL and PCBs are more exposed to saltwater in vented MHL fixtures. Sometimes an all-in-one fixture is not the most efficient in every aspect.
Thanks for the explanation WTAC. Once again you have greatly helped narrow down a best practice. I hear the 220v German dimmable T5 0-10v ballasts are reliable, but the ATI 120v models are generic ones from China that are yet to be proven reliable. I like the Icecap 660 dimmable ballast, but they cannot be governed by a controller such as Profilux or Apex which use 0-10v control.