Metal clamps a lot of the time will leave a small hole down the side as shown below (fig 2). This makes the consumer tend to tighten the clamp even tighter possibly distorting the solid port. Last week I examined two Diatom Filter returned with metal clamps. Both the casting were replaced because the metal clamps had permanently distorted the plastic casting ports. The best solution is to replace a broken rubber clamp with a original rubber clamp like the Diatom Filter was equipped with.
Another point I would like to share with you is the static grip that vinyl tubing will make on the plastic fidget ports. Hoses that have not been removed in sometime, should be pushed on to break the static grip.