i dont think that there is a need to do that. One or the other would be fine.
I guess my thinking was I might procure some MTS from someone I know who has some left, but not quite enough for my purposes, and I have some old aquasoil in an empty tank that I could use as well. The tank had only been up for about a month or two before it was taken down, but I left the aquasoil there, took everything else out. You think it'd be okay to use this year-old aquasoil?