Hydropure METALTRAP™ MT-10 10K gal Pool & Spa Pre-Filter. Never let metals in your pool again! Why just TREAT metals when you can TRAP them. METALTRAP™ is a unique, patent-pending, water filtration technology designed to selectively filter out stain-causing metals found in water. This synergistic media technology doesn’t just treat water, it chemically reacts with the metals and then physically traps them, removing them permanently from the water! It is also very effective on removing hydrogen sulfide, responsible for the rotten egg smell.