My swiftech 350 burned out today. I'm going to get an iwaki, but I don't know what to do about the barb sizes. I have a 3/8" loop, but I'm looking at the 20RLT and that uses 3/4" hose hookups. How do I convert, and can I go so low as 3/8" without causing the pump to stop functioning? I could also get a 30RLT or 40RLT at the store I'm going to, but they cost more. Would it be worth the extra money to get these pumps over the 20RLT?

I also don't have a res. does a pump this big need one to keep the pressure manageable?