I have started using cypress mulch as a semi-substitute and it works well. Get the "premium" bagged mulch found at Home Depot and Lowe's. It has less "foreign material" in it and be sure to rinse it well before using it in your potting soil. I do not find that fine or medium grade are worth having. I not only want to increase draining but also open up the potting soil. Only coarse will do both. I have to purchase huge, 4 cf. bags to get the "true" coarse perlite and I go though at least two bags every year. I sell it in 1, 2, and 3 gallon bags, Cameron. Contact me via T-Mail if you have interest.