150g drop down L reef tank

[sphelps]

That flushing toilet is the noise I warned you about previously when you use a single drain on that large of a drop.
Two drains, one back up and one with a gate valve, zero noise, zero air, everywhere (upstairs and down).
Crabs, snails and fish will find ways through your plumbing, unless you have strainers in your dursos that require constant cleaning you're vulnerable. Even a clump of algae can clog a valve.