Does Lava Rock Reduce pH

Because frankly lava rock by itself is completely incapable of lowering or raising pH. It’s completely inert.

Is lava rock acidic or alkaline?

The answer to that is yes. Lava is molten rock which has reached the surface. Lava composition varies from location to location. In some places it is the sort of material geologists refer to as ‘acidic’ and in other places, it is the sort of material geologists refer to as ‘basic‘.

What rocks will lower pH?

Decorate your aquarium with limestone or coral rock. As with driftwood for lowering pH, use a healthy amount of calcium carbonate rock to create the desired effect.