I bought 250 grams of tourmaline at a gem show. Crushed it into sand, laid it down on the bottom of my tank. I wasn't going to buy the Ada tourmaline bc which is tourmaline dust and powdered carbon.
I paid $30 but when crushed it was shiny inside, shards of crystals of blue and green!
Bought 250 grams of the Ada stuff for about $18. Did the same. It was just black... No crystals. Much lower quality... But I paid much less than what I got at a gem show.
If anyone would like to see the Californian tourmaline I crushed and look at the pretty crystals, here it is along with a pic of what Ada sells for you filter. The Californian stuff I bought Looked the same before it was crushed. When I crushed the Ada stuff, there were NO crystals inside. Much lower quality in my opinion.
This rough tourmaline is called Schorl. You can buy like three pounds of it on ebay for like $20! It's like tourmaline ore and not gem quality tourmaline.... But the same if not better as the schorl that ADA sells,
Do I KNOW it does anything? Nope. Do I think it does anything? I do... I buy into the whole ionization stuff. There is tourmaline in my hair brush, too.
Do I think I need a pound of crushed tourmaline sand in my ADA aquasoil? Absolutely not. Its in there just in case there are any benefits at all.
I call total BS on it being used to slowly supply lithium and boron or whatever Tourmaline is made of. Schorl is a rock. The minerals aren't bioavailable. Tourmaline has electrical properties, and as a geek I think that's cool, but it more than likely doesn't do anything for the aquarium or my hairbrush for that matter.
But it's there just in case, and thats why I choose to spend money on things like that.