To make sure that they get along, use skinks of a similar size and species. Enclosures can have several females, but males will tend to compete with one another. As a result it's best to give new skinks a trial run to see if they get along with the other skinks before moving them in permanently.
The difference is that a skylight filter is a basic colour correction filter with a slight magenta tint which has a similar effect on skies as a UV filter (which cuts out part of the spectrum), which is neutral coloured.
Filters that are ISO 12312-2 certified not only reduce visible sunlight to safe and comfortable levels but also block solar UV and IR radiation. To date four manufacturers have certified that their eclipse glasses and handheld solar viewers meet the ISO 12312-2 international standard for such products: Rainbow Symphony.