Mixing Fluval Stratum w/other substrates
I just received a bag of Fluval Stratum and realized that the bag I received was didn't contain enough substrate for a proper plant bedding. Before I spend $5.99 to return this bag for the bigger one, I wanted to ask if anyone had success with mixing Fluval Stratum with any other substrates. In my case, I have used Seachem's Flourite Black and have plenty of it in a separate 125-gallon tank. The Flourite Black has been in this tank for a little over a year and has never had live plants in it. I understand that on the bag it says specifically to not mix FS with anything else, but I'm thinking that they just say that to prevent people from buying from other substrate brands. If it's wiser to stick leave Fluval Stratum on its own then I will quit cheapin' out and buy the larger bag. Thank you!
Questions: 1) Would layering or mixing the FS with used Flourite Black be a bad idea? (Aside from aesthetics because I'm sure they will mix and could color clash)
2) If this is all right to do, would you suggest mixing the substrates up or layering them? I'd like to put the fluval on the bottom, but I'm wondering if this could be dangerous or pointless
for any reason. I intend to have the tank filled with plant life suited for cherry shrimp so I'm more concerned with whether or not the used Flourite Black could harm them or the water