20g tall pump/drain question

[mike tv]

posted this in nano reefs but im not sure that theyll respond fast enough for me to go buy the pump

im setting up my 20g reef with 10g sump/fuge and i was in the LFS inquiring about which pumps and drain sizes to use, and was told to cut 1.5in drains and use a mag7. this seems excessive, but with 4ft of head he said it would turn over 15 times an hour, which sounds good to me since i want to keep the number of powerheads to a minimum in that small of a tank
where should i place the drain? what size hole should i have drilled? what pump would you recommend?

 

[insacron]

With a four foot head a mag 7 should pump 480 gph, turning your tank over 24 times an hour and your sump 48 times an hour. I dunno that seems like a ton of flow to me, specially through the sump, but I'm no expert.

 

[crvz]

You want to keep return flow down in the 5-6x per hour in my experience, and then bring the overall display flow up with power heads or closed loops. If you push that much water through the sump, you may have some issues.

 

[insacron]

Is that turn-over for sump or display?

 

[mike tv]

thanks, thats what i thought
i figured the shady looking individual telling me this was just trying to sell me more expensive parts
what pump should i be using then? it will be somewhere between 30-40g TSV
the tank is in my bedroom, so noise is an issue
what would be the proper size mag pump? how loud are the mags? what would be the right drain size? i thought his 1.5" idea was reserved for 300g+ tanks
also, what would be a good skimmer for this set up?