I know I have seen this stuff (like seachem clarity)work almost instantly in freshwater tanks. I know in reef tanks it seems like every chemical you add causes a domino effect.
The only one Ive tried is the stuff for P. It works BUT it falls into the rockwork. I wouldnt use it unless you had a high flow BB tank and run 5 micron filter socks.
Don't know about Don but next I'm doing the 1 microns socks:| May end up getting an Eheim power filter. BTW I found a site that sells them 5 at a time, less than $20 shipped, high but until I find what I need it works.
Boomer I got a good deal on a mixed bag of 5 and 10. The 10's worked but the 5's were of course better. It works well but I wouldnt do it directly in my tank. I could see it just collecting in the sand or rock. In a big trash can its fine but now it just boils down to how to implement a good system. If I cant figure out a good way, it was interesting at least.