I’m planning out my new tank, and I’ll be using a pretty coarse layer of lava rock granules as the base layer in the substrate(.500-.750" pieces). The reasoning for this is to add more surface area for biological filtration, and to add height without having an anaerobic layer. My question is this… How thick can I reasonably go before I risk anaerobic respiration at the bottom? In case it’s important, this is going in a 125G tank, and I would really like places with the substrate 10-12” thick (7-9” of lava rock + 3” of BDBS). Will this work out fine, or am I asking for trouble here?