All peristaltic pumps are designed to operate with a specific tubing wall thickness and use of the incorrect thickness will adversely affect pump performance. Simply put, a mismatch results in the tube being "squeezed" too much, or too little, and neither scenario has a favorable outcome! If you're not using an ANKO pump and are unsure of the wall thickness, the calculation is: (outside diameter - inside diameter) / 2 = wall thickness.
Some ANKO pump heads have the ability to utilize multiple wall thicknesses by changing out the installed roller-assembly. Please see Parts & Accessories for all available assembly options.