I found some red powdered pottery clay for sale locally. These are the stats:
SiO2 64.27%
Al2O3 16.41
Fe2O3 7.04
TiO2 1.06
CaO .23
MgO 1.55
K2O 4.07
Na2O .40
P2O5 .17
L.O.I. 4.78
Would this be good to use in MTS mix?
Is anything in here dangerous to plant/fish/inverts?
The least they will sell me is 25#s which is probably 23#s more than I need.

SiO2 64.27%
Al2O3 16.41
Fe2O3 7.04
TiO2 1.06
CaO .23
MgO 1.55
K2O 4.07
Na2O .40
P2O5 .17
L.O.I. 4.78
Would this be good to use in MTS mix?
Is anything in here dangerous to plant/fish/inverts?
The least they will sell me is 25#s which is probably 23#s more than I need.