stwalkden wrote:

I'm planing to set up an amazon bioype tank in a 33 gallon tank. I have 2
aquaclear filters on this tank. I would like to a sand flourite mix as a
substrate, but am concerned about the sand getting into the filter
impellers. Or I can go with natural (uncolored) river gravel.

Sand and Flourite will separate over time-particle size, shape and density are
much too dissimilar.

River gravel which has a similar particle size to the Flourite will probably
stay mixed for a while.

100% Flourite will stay mixed forever.