Need help understand sw return pumps

[edwardclaxton]

Im setting up a 125 with a 40 breeder sump. I have a question about the return pump I need. I seen a lot of people say you need 20x-30x turnover. And I start looking at forums with the best return pump topics and they have a pump that rated at 900gph for a 180 gal reef. I guess my main question is, is the turnover rate is that how many gph that goes through the sump, or is it the water movement in the display including power heads or anything the cause water movement? I just dont understand when they say 30x over on a 180 with a 900gph pump. The turnover would be 5? Thanks

 

[T1KARMANN]

Flow rate depends on head height basically how far the pump needs to push water

If you have a 900 gph pump and your return pipes are 4ft you will lose a fair bit of flow

I have a 30,000 lph pump on one end of my tank but it pushes 4m so the flow is probably 22,000 lph

 

[Mrc8858]

Your 30-50x comes from total flow rate in your DT including all pumps. Sumps are usually 5-10x leaving the rest to be done by the circulation pumps.

 

[edwardclaxton]

Ok thanks its about 4 ft. see I watched a video from reef dynamics about skimmer in which thats where I ended up getting my skimmer, he said the the gph through the sump should only be 5 to 10 times. Thats why I started looking it up. He said it gives the skimmer longer contact time. Im yhink about the ehiem 1262. A lot of people use them on a 125.

 

[T1KARMANN]

I feel the total turn over of any tank SW or FW should be a min of 10 x per hour