Not really sure there would be any benefit to using the two in conjunction. The diatom should be pulling out particles down to 5 micron (possibly smaller). Pretty much anything the UV would be killing would already be screened out. Also the UV is best run for a longer period of time than the diatom filter.
When I use a diatom filter it's typically only for a couple of hours at most.
Anybody have a diatom filter with a uv light hooked up to it I use a diatom filter and instead of cleaning after every tank was thinking about getting a uv light to go with it if you do what kind and size thanks