i have the pro120 with 3/8" barbs, i want to switch one of the barbs out for a 1/2" barb so i could use 1/2" ID tubing for HC --> modded mcp350 w 1/2" barb inlet, i went to home depot but they only had barbs with huge threads, could someone please give me the specs of what i need to get and where from? thanks a bunch