Choosing between a Koralia 4 and a Nanostream 6045

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I have a 120 gallon mixed reef, over the past few years it has gradually been moving in an SPS direction although there are still plenty of LPS, a few soft corals and about five BTA's.

My only flow is the Mag 12 return pump, I know I am severely under-powered as far as circulation goes. I do have a sand bed about 1/2" to 1" deep which I am willing to get rid of if necessary.

I was looking at getting either a Tunze nanostream 6045 or else a Hydor Koralia 4. I would put the pump at the far end of the tank away from the BTA's of course. The other option I really liked was the Vortech, the price is not so much a barrier but I thought it might be too much flow.

The reviews I have read about the nanostreams say there have been issues with the impeller and also issues with the mounting bracket breaking. I understand Tunze has tried to fix these issues.

So I need advice on the 6045 versus the Koralia 4. Factors that will go into the choice include: noise, aesthetics/size, reliability, and flow characteristics.