Cooling tubing ?

[SScnc]

The tubing that came with my laser has gotten very hard and I want to replace it. Is this the correct type and size for a 40 watt CO2 ? http://www.lightobject.com/8X12-Silicon ... -P752.aspx

Will it harden over time. I do add bleach and antifreeze, not sure if this is what causes the hardening (?)

Thanks for any advice

[Tech_Marco]

The silicon tube should last 2~3 years without solidify issue if use with fresh water. I think the chlorine caused the problem

Marco