Mugwump's Fish World

...found this to be informative and interesting.....

http://aquaristmagazine.com/lowering-aquarium-ph-effective-methods/ (http://aquaristmagazine.com/lowering-aquarium-ph-effective-methods/)

(http://aquaristmagazine.com/wp-content/uploads/2014/04/coco-leaves.jpg)

Good article.  I've used catappa leaves and alder cones in some of my tanks. The alder cones seem to be a favorite novel item for the cherry shrimp. I haven't done the math but it may take quite a few leaves to lower pH in a large tank with a higher TDS. I used these mainly to create a blackwater appearance in tank with the wild type angels.

I've never tried the catappa leaves, but have used alder cones......alder cones are good for cory fry, it helps keep bacteria down too

My favorite article on the medicinal properties of such things is, "All the leaves are brown?" by Colin Dunlop over at http://www.seriouslyfish.com/all-the-leaves-are-brown/ (http://www.seriouslyfish.com/all-the-leaves-are-brown/)

I can attest to these things not have much effect on truly hard water.  I can put a bushel basket of leaves in my Ohio well water and it turns brown and murky but stays hard as hell with a high pH.  On the other hand, I can drop a handful of leaves into some rain water and quickly make battery acid.  LOL

Dennis