I've just added this thing into my filter to optimise my biofiltration. I've heard from the Tencho that it will raise the kH by 2. Usually I raise my kH every waterchange with Baking Soda. Now I can skip that.

After a 50+% waterchange yesterday, I added in the rings. This evening I tested the KH to be around 4-5 and pH around 6.5. There's nothing wrong with my CO2, the ADA soil reduced the PH also.

So if you want somethign that will maintain a +2KH, try this Mr Aqua Bio Rings. The surface area is also looks very huge as the rings are ultra porous.

Here's a pic http://www.imagestation.com/picture/...3/f9691a86.jpg