Mix or layer the substrate?

[squidbait]

If I use Southdown and want to seed it with ls, do I mix the two together, or layer them on top of each other? I am going for a 4" base in a 90G. tank. Thanks as usual!

 

[rickt4du]

Actually, I put the live sand in first. Dont guess it matters, really.

 

[dburr]

Put the live sand in last.

 

[nm reef]

not sure that it really matters a lot.......personally I added some natures ocean ls....then carib sea aragonite...then natures ocean again on top.....sort of all mixed up now.............but seems to function well enough

 

[broomer5]

It doesn't matter if you put the live sand on top or bottom or mix it up with "dead" aragonite sand.
What - the bacteria have a preference now ?
They will populate all areas of the tank eventually, and I really don't believe that bacteria have the capacity to "think" what direction in a sandbed or saltwater aquarium to migrate to. They will populate and reproduce according to the water conditions and nutrition source.

 

[fender]

It really doesn't matter, within days bacteria will spread and as the various worms, pods, bacteria, multiply they will 'mix' things up.