Quick pic before assembly

[Aquattro]

Tony, not sure why a second would be desired. I think one will work just fine. The pump may not be strong enough, but a single beckett can inject sufficient air into a water column this size. A second injector would also need a second bulkhead, injector housing, tubing, ass't plumbing, etc. I'd also have to run a second pump to benefit at all from it, so you can see the cost goes up quite a bit for little, if any benefit.