Your epoxy and plastic

[heyfredyourhat]

Check lordco or maybe other auto parts place for fusor products. We use fusor products for all our plastic repairs at work(bodyshop). Its like 50+ bucks per tube but it is very strong and it will seal anything you need. I used fusor 142 on my reeflo pump to stop a leak and so far so good.
http://www.lord.com/Home/ProductsSer...1/Default.aspx

[wickedfrags]

While it may work I would not recommend it for plastic. Best to find an adhesive specifically for material of your skimmer.

Epoxy has a few applications IME and include attaching corals, leveling low spots in live rock to better facilitate aquascaping, making bases for acans, zoas and other encrusting corals, among others.