New tank coming....

I have 4 6.5g acrylic tanks I plan to keep some shrimps in. I will have plants in there like Banana Plants, Jave Ferns and some moss varieties....but, main focus is for these tanks is for about the shrimps rather plants.

After reading on here few a little while today seems as thought Fluval Shrimp Stratum substrate is the way for me to go with.

Question is, How much of this Shrimp Stratum would be suggested in each tank?
The footprint is 14"x 9"x 12".
I will not be doing any special with the aquascaping but will have some driftwood and some mineral rocks.


Also, will I hinder the buffering from this substrate if I were cap the stratum with a 1' of black diamond sand?