[EvenFurther]

You could do that.

But it might throw off the drain rate. Many tanks have tuned BA or herbie drain. As the pad builds up, that will affect the drain rate and could lead to a flood, and throw off the return/drain tune.

Your much better off draining to the sump, then filter there. My set-up is fail safe. Even though it is unlikely, if the pad builds up too much, worse thing it will overflow into the next chamber.