The UV lamp reverts to a regular lamp when picked up.

Also, is a single UV lamp meant to keep purple wisps from leaking through? or are we meant to stack them close together to improve their effect? As it seems the single lamp still lets a few get through. They're pretty power heavy so hopefully they don't need to stack too heavily to get the job done.

Thanks for feedback!
1. "The UV lamp reverts to a regular lamp when picked up."
This will be fixed in the next release (within a day or two).

2.
A single UV-lamp is enough to rid of a wisp which was for at least 4 sec in the square 21x21 around the lamp. This wisp can still live for a few seconds after UV-damage.

Thus it is best to build several lamps, but not together. You could also try to use the lamps in a pulsed mode to save power.

You can also destroy the place in the woods (it is enough to reduce the number of trees in the forest below 200 per chunk or destroy specifically those trees from which wisps rising currently), from where the purple wisps are flying at the moment to your base. They fly out of the same forest for three days in a row.

Fixed for version 14.22.3