ASM G2 is way overkill for a 30 gallon......Size the skimmer accordingly.....Just because you oversize doesn't mean you'll gain any performance....In all actuality; you'll probably loose because it's way oversized and won't skim efficiently or consistently.....A little big isn't a bad thing, but way to big....
If I were searching I'd probably opt either the Reef Octopus or an alternative would be a SWC
Reef Octopus 4" Recirc skimmer.....
ASM Mini G.....Not a fancy looking skimmer but does perform.....rated to 75 gallons...
Euro Reefs aren't made anymore, but look for 1 used at a fair price would be an excellent choice as well......