all good my friend
indeed... as mentioned above, I am in favor of using UV. Its just a shame how the hobby industry marketing can mislead folks into misapplications.
Hatchery/aquaculture/science experience teaches us differently (and properly).
The first problem with UV in the display is that we are allowing the parasites/pests into the system by unquarantined (yikes!) organisms (plants, algae, corals, fishes, etc) with the hope that the UV is ready and able to kill them. Doh! Just not safe or proper husbandry.. Instead, QT first to screen for gross problems... then rely on good husbandry and stability for natural mechanisms and immunity in the display.
The second problem is application. Systems with substrate (sand or gravel) harbor numerous nasties (larval organisms, cycts, tomites, whatever

) which is in conflict with UV efficacy. Best to have bare bottomed applications where the little buggers can be constantly swept up and kept in suspension for a better kill ratio.
And speaking of kill ratios

...
for a UV to have any prayer of working reasonably well... the water has to be polished (heavily prefiltered), clear (daily carbon or ozone) and rather slow. Most people instead hook up a water pump to their UV and let the sucker run
Other issues... the chamber needs to be well flushed/cleaned frequently (months) with bleach or the like to prevent any bacterial slime or mulm from building up and impeding the penetration of light through the quartz sleeve.
Bulbs are likely only good for 6 months at best... and the list goes on
Heehee... I truly do find good use for UV... but again, in more commercial settings or for bare bottomed QT tanks.
Bottom line... for practical aquaristic applications, UV is strict to employ and marginally useful. Excellent for preventing unicellular algae from growing... weakly useful for parasite control. Really just a drain on the electric bill and a killer of desirable plankton. Also some theories about stripping nitrate and spiking nitrites in systems with heavy nitrates.
I find ozone to be much easier and more effective for disease control while having many other benefits (water clarity/color, improving skimmer performance, O2 saturation, etc).
Hope it helps my friend
