Review on 🐠 CorisRx Premium Lifestyle Aquarium Equipment: 7.8"x5.5" Undergravel Filter for Fish Tanks with Air Pump, Enhancing Filtration Efficiency by Stephen Tharpe

I only bought this because I wanted to filter a container full of sea water. Multiple photos and videos included. When I bought it it was pretty cheap at $13 but now it's back to $18. I wouldn't buy it for €18. Since I need a second one for the other half of my container, I bought another used one for $10. The first picture is after 3 hours of filtering muddy sand water, I don't know if it was a filter or just sand deposit. The second picture is different. 3 hours filtration, total 6 hours. Judge for yourself. I've also included a video to show how it works. (after the first 3 hours of filtration)