Pondering New Return Pump Question

I currently have a Mag 9 running the return. And a Mag 7 running the skimmer.

I have about 4 feet from the pump to the bottom of the tank, where it then goes up tot he returns. I have about 3 feet of line between the pump and the skimmer.

The Mag 9 says 800 at 4' but what is the 4 feet consist of ?

I am pondering whether or not to get a MAG12 for the return and use my Mag 9 for the Skimmer. This should make up for the head loss.

Question is
How do you messure the distance so you know what the capacitiy of the pump is ?

As for why, well when I was cleaning the tank, I put my hand in front of the return in the water and it jjust didnt feel that impressive of a flow.


Cheers

 

I don't know much about all of this..but i encountered the same problem..so I just got a pump that wasn't ridiculously big..but big enough.. and adjusted the flow with a ball valve until i got the flow i wanted..i have it set about 3/4 of the way open now..maybe not the most efficient route..but it works

 

The head is the vertical measurement, so only the vertical distance equates to that.
The rate should be about 5X of tank capacity. Any more and you are just pushing water through the sump faster than your skimmer and fuge will be able to work it efficiently. So if you are pushing 800GPH at the tank for the return, you are most likely already exceeding that. Remember, the return pump is only for returning the water to the tank, not to create flow. That's what power heads or closed loops are for.

 

So if I have a return line that runs 4 feet from the return line to the tank with most of it being horizontal, then there is 3 vertical feet as it goes up the return chamber of the tank out to the return, is that only 3 foot head loss I am worried about ?


Sounds like I may be ok then as is

Cheers

 

Other things add to head loss too, although somewhat minimally until you get into complicated plumbing setups. Just going straight vertically to a return you shouldn't have too much head loss since the plumbing is fairly simple but technically all the pipe, each elbow, each valve etc adds to some backpressure on the pump.

How long has the tank been running? Plumbing can get gunked up with algae/calcium carbonate precipitation etc over time.

 

Just over a year I guess. Dont think its gunked up, just re evaluating flow.

The return tube runs from the sump to the PVC then up through the overflow. So about 3 feet horizontal with 4 feet vertical with one elbow.

It may be fine, but if this was 800gph what is it with the above mentioned travel ?

 

Depends on the size of your plumbing.

A mag9 should run about 650gph with 3/4", 750 gph with 1" plumbing. Generally speaking anyway.

This is the head loss calculator I use, doesn't have every pump in there but you can at least get the amount of head loss and compare it to a head loss curve chart for whatever your pump actually is.
Reef Central Online Community

 

Cool,
I will run the numbers and see where I end up

Cheers