WB Cube20 Owners, sponge or nah?

[LagunaGlide]

I have had my Waterbox Cube20 set up for a few months now, and things are going well. I have put some marinepure in the middle chamber sitting on top of one of the provided black sponges. I have only replaced it once, and am about to remove it again tomorrow. Are people actually using these things in their reef tanks? I am using the filter sock that I loosely filled with floss, and I really can't imagine anything is getting through that this large pore sponge is going to stop.

Thanks for thoughts on this.

 

[Ron Reefman]

bump

I have a HOB filter on my 16g frag tank. I put 2 sponges in the system with a layer of filter sock material between the 2 sponges. The bottom sponge gets a bit dirty, the filter sock material gets black and the top sponge stays almost clean.