I am just getting back into bonsai after a long hiatus caused by a hectic schedule that led to the loss of all my trees. I have sifted 1/8-3/8 inch pumice and sifted oil dry (currently testing with freeze/thaw) and access to decomposed granite. I can’t find small sized pine bark or lava rock. I’m not going to buy the small bags costing $15-20 off the internet. Do you guys just buy the big bags from garden centers and sift them. it seems a small portion of it would be small enough. Is there any reason to use lava rock with the pumice?