I use a similar mix, pine bark, pumice, hadite which is very well draining. The good thing is it is almost impossible to overwater, the bad thing is it dries oit pretty fast. So I vary the amount of pine bark to compensate with more for plants needing moister soil. Pines get about 10% pine bark, most decids get 20%, water hungry species like bald cypress, hinokis, hemlock, etc. get 30-50%. You can still add more pine bark if their soil is too dry for your trees but at 25% already it sounds like a good general mix. You actually may need to add more pumice or lava for pines and junipers.