thx for your advice.
decided to mount my 52hd with AI ext rail ,15 inches above the tank, would love to hear from you about the DIY diffuser. heard from my friend SLW10s flow is way too strong for 45cm cube, so going to drop that and add innovative marine spin stream nozzle instead. Since the nozzle will reduce the flow dramatically, going to run with Jebao DCP-5000, hope 5000lph will be sufficient to circulatethrough chiller and the spin stream nozzle.
My tank will be arriving on 2~5may so i still have time to make amendments but now i have another problem, gotta convince my boss