VekonnCat Water Fountain 6 Filters Pack for Stainless Steel Top Fountain and Yellow Stamen Fountain

do these filters have a plastic bottom or are they flimsy?

How often should you change the water?

The cotton is white so I’m guessing it’s been bleached. Any research done on the chemicals the cats are being exposed to because of this?

will these filters work with the Vekomn plastic top water fountain?