You don't need liners. Just use the plastic net pots.
The liners are one more thing to clog and host bacteria and fungus and algae.
As long as the hydroton doesn't fall out, and it shouldn't as they were designed to be used together, the liners are simply one mroe item that's GREAT for parting growers and their money.
The liners are necessary with a finer particle like perlite or coco coir, which WILL fall through and clog up your delivery systems.