My experience with Floramax
I just traded out my inert gravel for Floramax this weekend. My advice would be to wash the new stuff pretty thoroughly first. I think Floramax and Ecocomplete are pretty comparable as far as water clouding goes.
I emptied the 12 pound bag into a 5 gal bucket and ran water over it constantly in my basement sink for about 30 minutes, mixing it up with my hands intermittently, dumping and refilling and that seemed to get most of the cloudiness out.
I ended up keeping about 1/3 of my old gravel in the tank and just mixed in the new stuff. Cloudiness was still present but it cleared 2-3 hours after running the filter and using the clearing agents that came with the Floramax.
I had my fish and plants in buckets for about 6 hours (being bubbled with an airstone) during all of this changeout and they were fine - I don't have experience with shrimp.
I'm really happy with the change - the plants are already looking perkier and I don't have to think about adding root tabs any more.