LParker480
Community Member
I'm assuming the max head pressure rating of a pump, is its ability to pump vertically? if this is correct, is there a way to figure how the GPH is affected by the vertical rise?
Max Head Pressure question
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mcarroll
10K Club member
Reputable manufacturers publish charts with flow curves, or an equivalent table of data. The best also cross reference power consumption across the curve.
Usually your reseller will also publish this info. Consider a different reseller and/or different manufacturer if you can't find a curve for the pump you are looking at.
Usually your reseller will also publish this info. Consider a different reseller and/or different manufacturer if you can't find a curve for the pump you are looking at.
TheEngineer
Formerly icecool2
It's not technically just vertical pumping, it is how much backwards pressure on the pump can be overcome. That's a combination of plumbing and vertical height changes, There are some really nice calculators out there that will show you head loss for your setup. 90 degree elbows cost more in your max pressure than two 45 degree elbows, for example.
As @mcarroll said, any decent pump manufacturer will give you the curve. Many will give you a power curve too. The power curve will help you pick a pump that costs less to run at the pressure you need.
OP
OP
LParker480
Community Member
ok guys thank you. The return pump in my sump will be about 4.5' below my display tank. So I'm needing to size my return pump based on its GPH with factored head pressure for my over flow. I'll look into the charts/curve and should be able to answer my own question. Thanks again
mcarroll
10K Club member
+1
For a typical, straight-shot from your sump to your tank, just minding the curve will do you fine.
If you're doing anything more fancy, such as multiple outlets, submerged spray bars, manifolds, et al....you'll want to use one of the friction loss calculators.
I like this one:
http://www.freecalc.com/fricfram.htm
It's more complete without being insanely complicated, adn can be used to select any brand/model of pump.
The one on RC isn't bad though, but it's specific to the pumps they've chosen to list.
For a typical, straight-shot from your sump to your tank, just minding the curve will do you fine.
If you're doing anything more fancy, such as multiple outlets, submerged spray bars, manifolds, et al....you'll want to use one of the friction loss calculators.
I like this one:
http://www.freecalc.com/fricfram.htm
It's more complete without being insanely complicated, adn can be used to select any brand/model of pump.
The one on RC isn't bad though, but it's specific to the pumps they've chosen to list.
mcarroll
10K Club member
Exactly!
This may also help.
For actual flow, you need:
- [Display Tank(s) Size In Gallons]x[2] = Good Flow
- x[4] You can go up to this much flow pretty much without issue, but I wouldn't go out of my way or spend extra money to do so.*
- x[5] and above can be problematic and end up giving you drain/noise/bubble issues to solve....not necessary, but shoot for no more than five-times if you must have "more flow".
150 gallons display
50 gallon frag tank
100 gallon sump
50 gallon frag tank
100 gallon sump
You'd use:
[display tank + frag tank = 200 gallons]
...as your equation to figure volume. Sumps or other "empty" water vessels don't really count toward your skimmable volume.
...as your equation to figure volume. Sumps or other "empty" water vessels don't really count toward your skimmable volume.
So your desired actual flow rate would be anywhere bewteen these two...
200 x 2 = 400 GPH
200 x 4 = 800 GPH
200 x 4 = 800 GPH
More is not really "better", so consider anywhere in that range GOOD.
You'll find that this range corresponds nicely with the flow rates you'll find in most good, oversized skimmers as well as almost all other gadgets you'd be likely to have in your sump.
2¢
* You shouldn't have to spend much different money for 2x vs 4x....you probably won't have to decide based on cost.
Brew12
Electrical Gru
So you don't recommend adding in the water volume of the sump?
OP
OP
LParker480
Community Member
good information guys. this will help out a ton with my build. I def appreciate all the help!
mcarroll
10K Club member
Nope. Not in any ordinary case. Does Tunze want you to switch your 75 gallon tank from a 9410 skimmer to a 9480 just because you're silly enough to have a 400 gallon sump?
Silly example, but your skimmer should really be sized to the bio-load....sizing to the display tank(s) is a decent proxy.
2¢
Brew12
Electrical Gru
I missed that we went from looking at return pump size to skimmer size even though you clearly stated "skimmable volume". My bad and thanks for the clarification!Nope. Not in any ordinary case. Does Tunze want you to switch your 75 gallon tank from a 9410 skimmer to a 9480 just because you're silly enough to have a 400 gallon sump?
Silly example, but your skimmer should really be sized to the bio-load....sizing to the display tank(s) is a decent proxy.
2¢
Hmmm. Pondering...Nope. Not in any ordinary case. Does Tunze want you to switch your 75 gallon tank from a 9410 skimmer to a 9480 just because you're silly enough to have a 400 gallon sump?
Silly example, but your skimmer should really be sized to the bio-load....sizing to the display tank(s) is a decent proxy.
2¢
I have always assumed skimmer ratings were for total volume, including sumps, not bio-load, which seems so incredibly subjective.
mcarroll
10K Club member
So the "skimmable volume" is the 200 gallons I calculated in post #6. I just didn't name it in that post cuz I was in a hurry (and we weren't yet talking about skimmers)... 
And then forgetting I had left it undefined, I used the term in an example as if it would just be understood. Doh!
But you got it anyway!
And then forgetting I had left it undefined, I used the term in an example as if it would just be understood. Doh!
But you got it anyway!
mcarroll
10K Club member
I don't mind, but we're definitely off of the return pump subject at this point.
Just saying...now on with it! I don't think there's an agreed upon standard for return pump or skimmer sizing by anyone outside of maybe this thread
....but the numbers work out like I was saying. Your skimmer, if "normally oversized" will generally have the same water flow rate as the x2-x4 rule of thump for the return pump.There used to be more skimmers that published this info....flow rates aren't known for a lot of skimmers, so the coincidence isn't so obvious.
Anyway, you will do well if you approximately match the sump flow to your skimmer's flow.
There's also the fact that most sumps are't huge like the silly example I made – quite the opposite.
If you added the sump volume to the system volume on a typical system, nobody may even notice.
So given that reality and the fact that it just doesn't make sense to me to skim an empty tank of water, I calculate based on populated tanks only. My original silly example was just to make a clear scenario to think about. If it made sense to count the sump, then you'd count it even if it was ten times the volume of the display.
Again, calculating return flow is guided by the same idea.
2¢
Brew12
Electrical Gru
And if you use your sump as a refugium with livestock that adds to your bioload you would need to take that into consideration with skimmer size also, right?I don't mind, but we're definitely off of the return pump subject at this point.
I don't think there's an agreed upon standard for return pump or skimmer sizing by anyone outside of maybe this thread
There used to be more skimmers that published this info....flow rates aren't known for a lot of skimmers, so the coincidence isn't so obvious.
Anyway, you will do well if you approximately match the sump flow to your skimmer's flow.
There's also the fact that most sumps are't huge like the silly example I made – quite the opposite.
If you added the sump volume to the system volume on a typical system, nobody may even notice.
So given that reality and the fact that it just doesn't make sense to me to skim an empty tank of water, I calculate based on populated tanks only. My original silly example was just to make a clear scenario to think about. If it made sense to count the sump, then you'd count it even if it was ten times the volume of the display.
Again, calculating return flow is guided by the same idea.
2¢
RudyB
Active Member
Just in case here is a calculation that seems to work well and I have used it multiple times:
For every 1' of vertical line = 1' of head pressure (simple enough)
Ever 90 degree elbow = 1' of head pressure
Then for every 10' of horizontal line - 1' of head pressure
Now for every 45 degree elbow it counts as 1/3 the head pressure (or .33')
If you use flex lines the calculation is harder (depends on what type of line you are using).
For every 1' of vertical line = 1' of head pressure (simple enough)
Ever 90 degree elbow = 1' of head pressure
Then for every 10' of horizontal line - 1' of head pressure
Now for every 45 degree elbow it counts as 1/3 the head pressure (or .33')
If you use flex lines the calculation is harder (depends on what type of line you are using).
RudyB
Active Member
I would also suggest that you get a DC return pump that is larger than you need. Remember that you will not have to run it at full but if you need to you can. If you get a regular pump that is it. As for the skimmer, it would depend on the amount of fish that you will be adding. Yes, everything in the tank has a Bio load but not the same count on load. I would go by the total water volume as a good starting point. If later you add more fish than you though then add a bio pellet reactor and place the out put of the reactor to the input of your skimmer and it will keep your skimmer working at full.
