Hello friends

Please to meet you .Is my first post here.I have a question for you if you can to help me.I want to make a aquarium chiller with 1/4 compressor..Aspera NE 6170Z,with 134a.What length must have tubing for evaporator with pipe 3/8 or 1/2?The evaporator is orange in the picture..

2012-07-18 13.39.48.jpg