Mainstays Scum Sponges in White & Gray for Spas - Quantity - 2 - 3 in. x 2.6 in. x 3.5 in.

I can’t confirm whether it was the scum sponge or the filter sock, or a combo of both, but my pool went from murky to crystal clear within a day of using both. And for the the nominal cost for both , there really was no investment. P.S. the pool sock I used on the intake to the pump. Cut and held in place with an elastic, really stops a lot that would clog the filter. Works great for a small spa or hot tub but not adequate for larger units(over 1000L). Have used other similar products that work better. Tried it out for our hot tub. At first didn’t notice much, but now it is picking up the grunginess that comes from skin, like lotions or body wash residue. Every two weeks we rinse it and put it back in.With a swim spa we have a large basin. This floating sponge breaks the 'surface tension' of oily film on top the water and slows down the formation of scum on the walls of the spa. The sponge works best if we have the correct jets open and circulating the largest swirl pattern in the water while in rest/filter mode on the spa. The sponge aided in this obvious discovery. So, in more ways than one, this product helps with maintenance of a spa.