Strictly looking at results, not much is going to beat a diatom for polishing. However, I prefer to use an HOT Magnum for my water polishing duties because its cheaper to buy & easier to setup, plus I can move it around to whatever tank I want to polish. It flows a lot more water & I can also use it for simple mech filtration if one of my other filters dies (just switch to the blue pad instead of the micron filter). Again, I can't think of anything that would polish better than a diatom, but I had to weigh in the versatility of the unit. I just couldn't justify that much money for a single-purpose diatom when the HOT mag polishes almost (95%) as well. I can't even see the difference in my small tanks, but it may be more noticeable in a monster tank...