I use 1/4” polyethylene. I cut a new piece for each sample. Here is a 300- foot spool for about $30. That’s 10 cents a foot, or about 30 cents a sample.I bought one of these on Amazon. It didn't come with the tubing needed to reach the sump. The instructions are printed in a two point font that I need to use a magnifying glass to read. It seems that it will accept tubing from 3/16 to 5/16-inch. That's a pretty broad range. What size and type of tubing do you suggest?
https://www.amazon.com/dp/B08FCJZLRZ?ref_=ppx_hzod_title_dt_b_fed_asin_title_0_0