Has anyone here had any experience with these? I was talking to one of my managers about it today and we started coming up with a filter system (more hypothetical than anything). Just wondering if anybody has any knowledge or stories with this kind of thing. Any thoughts?

We were mostly talking about freshwater systems (from what I understand, most methods seem to revolve around a very slow flow-rate), but I'm definitely still interested in marine systems (I guess the main one would be the use of deep sand beds).

Anyway, this is more of a discussion - I don't really have any particular questions (although I'm sure I'll think of some over the next few days). Thanks

Nitrate filters are very good, the very slow flow rate through the filter provides water with a negative redox potential - or devoid of oxygen. Increasing the flow rate increases the redox potential to the positive.

Still, for removing nutrients, I do prefer a chaetomorpha/caulerpa sump for marine systems, or plenty of fast-growing plants/water changes in a freshwater tank.

Nitrates can even be pretty useful! In Malawi tanks excess nutrients encourage extra algae growth on which the fish can graze; free food!

Redox potential? I thought that had more to do with electron movement.

Yeah, I guess there are plenty of ways to go about it. I just thought it was sort of interesting that they weren't more 'popular' - particularly for beginners. Surely the prospect of a piece of equipment reducing the potential maintenance time would be tempting.