stupid question

[27goldfish]

I should know by reading on the site for awhile now, but woiuld you use lava rock in a spillway that has bio media and a filter in it?

 

[HIROHITO99]

I'm no expert, but it's my understanding that you can use almost any type of stone just so long as the water is moving across it. Rocks at the bottom, where there's no circulation is what causes toxic conditions to the fish. Rock on a spillway should be okay. Don't take my word on it though... wait for one of the more experienced ponder's to wade in and either confirm or deny what I've said.

 

[DrDave]

Lava rock in a spillway will work fine as a bio filter as long as it is always running and wet.