question on using perlite in the 5-1-1 mix
if the purpose of perlite is to add aeration to the mix and the pine fines also add aeration to the mix, why not replace the perlite with additional pine bark of proper size?
to take it a step further, if there is sufficient, very fine ground pine bark in the mix, i would assume you could eliminate the peat.
if both the perlite and peat can be replaced with proper size pine bark fines, then couldn't you have a 5-1-1 mix of 100% pine bark??