if the company is not responding back than i would suggest going another company like Tunze. I had heard good think about the hang on the back skimmer and customer service is good as well. Why waste your time and headache if the company is not being responsive?
I just picked up a PLS-50 from Cadlights. So I can confirm they are still in business. But their email communication is the worst I've ever had. I sure hope I never need their help/support in the future.
I bought the RIO PLUS 800 PT VENTURI PUMP, It works for PLS-50 Elite 2. The only drawback, it is an AC pump instead of DC and the impeller is not needle pins. I am looking to replace the impeller with needle pins but so far no luck since the impeller has no specification.