Lava Rock in a wicking bed

I have a bunch of red lava rock from the big box store that is not being used.  Would it be wise to add it to the bottom of a wicking bed?
How would that affect the pH of the soil over time?  I also have a lot of expanded shale (Permatil) that I can add also.  I am thinking these would
add to the soil biology by adding a porous surfaces for bacteria.

Any suggestions?

I have a wicking bed with lava rock. I have seen no adverse effects. In fact, it grew the biggest yellow squash and zuchini i have ever grown. Easily twice as big as ones i planted in the ground. It was my first use of a wicking bed and i am a believer

that is what I was hoping to hear.