Drain Flowrate

[Techie_]

I'm starting my new 75G that I picked up for free, the drain pipe is 1" in diameter and flows through a 1" elbow at the bottom of the tank and the return in 3/4"

Can anyone help me out deciding which pump I should get and determining flowrate?

 

[dbl]

If my memory serves, I think a 1" pipe will flow at around 950+/- gph via gravity, and unrestricted. It won't be unrestricted in your case so I think you can assume somewhat less.

My suggestion is to look at some of the newer DC pumps due to their adjustability. Opinions vary, but I think if you shoot for around 10 times turnover from your return pump, it's a good target. So in your case, 750 gph. You add additional flow with in tank pumps/power heads.

Just one persons opinion!

 

[CastAway]

Here's a link to an old post with some flow rates by size...
Flow Through PVC at Specific Depths
https://www.reef2reef.com/index.php?threads/Flow-Through-PVC-at-Specific-Depths.208700/

 

[AZDesertRat]

Another thing you have to take into account is the volume of your sump. If you have a small sump stick with a lower gph pump or the velocity through the sump will carry microbubbles back to the display. If you have room, go as large as possible on the sump.
My display is 100g and sump is 30g and I wouldn't go any smaller. A 20g sump probably only holds 10-12g when in operation so a pump at 750+ gph moves water through the sump pretty fast and could potentially cause problems.
Look at not only the overflow and pump but also your sump working capacity and most efficient flow for your skimmer.

 

[Techie_]

If my memory serves, I think a 1" pipe will flow at around 950+/- gph via gravity, and unrestricted. It won't be unrestricted in your case so I think you can assume somewhat less.

My suggestion is to look at some of the newer DC pumps due to their adjustability. Opinions vary, but I think if you shoot for around 10 times turnover from your return pump, it's a good target. So in your case, 750 gph. You add additional flow with in tank pumps/power heads.

Just one persons opinion!

Here's a link to an old post with some flow rates by size...
Flow Through PVC at Specific Depths
https://www.reef2reef.com/index.php?threads/Flow-Through-PVC-at-Specific-Depths.208700/

So a pump like this may work? http://www.bulkreefsupply.com/quiet-one-pro-series-3000-758-gph-lifegard.html

I've read the chart and I should be getting around 275gph from my bulkhead. Wouldn't 750gph be too much in this case?

 

[TylerS]

Something to consider. Using the pipe flow information posted above I calculated the max turnover rate that the drains allow of some common mass production tanks, and found some of them to be in the 4 to 5x tank volume turnover rate. I don't think you need to go for 10x. But don't just look at the number on the pump, you'll never get that flow rate when you add pump head height and pipe restrictions.

 

[Techie_]

Something to consider. Using the pipe flow information posted above I calculated the max turnover rate that the drains allow of some common mass production tanks, and found some of them to be in the 4 to 5x tank volume turnover rate. I don't think you need to go for 10x. But don't just look at the number on the pump, you'll never get that flow rate when you add pump head height and pipe restrictions.

I should get 4.6 gallons per minutes. Which scales to 340 gallons per hour, much closer to 4-5x turnover. What's your opinion on what rate I should go with?

 

[oceanhighz]

that rate is fine. For example, I have an 80 gallon tank, with a 20" cube sump. I have a jebao dc3000 return run on the lowest or second to lowest setting. I prefer using mp-40/mp-10 for the main tank flow, and only use the return to have water sent to refugium and skimmer to remove waste. The slower the water moves through there, the more waste the macro and skimmer can collect