Determining Head Pressure and what pump I need..

[raymond4133]

I have always been thinking of replacing my two submerged pumps in my sump with something energy efficent...It would be good if I can do one powerhead or pump and connect the two plastic tubings to hit by splitting the flow...

I think that the overflows bring about 600gph max on each side...It's the AGA megaoverflow ....So that makes 1200gph total that needs to make it into the tank every hour....

But how do I calcualte head pressure...Is it the total height from the sump (which would be the floor) to the lid of the tank where the pipe extends out into the aquarium...

I'am also looking for something that is very energy efficent less than 140 watts max...Peferbally less than 100 watts but I doubt there is something out there...And I prefer not to do plumping...I just want to connect or splice the two plastic tubings I have in there right now and boom there I go...

I also heard somewhere the water pressure or head becomes more when there is a 90 degree bend in the flow of the piping...So in my case there would probalby be one or two bends max...

 

[CaptiveReefSystems]

if you go to the sequence web site, they have a great chart for sizing pumps to flow.

 

[dots]

There is also a head loss calc on the RC home page......

The easy way is to get it sized from the above two.....if you like I can explain your questions for you, but the answer could get long if you dont mind a little background in Fluids. In a nutshell it takes pressure to move the liquid, when pumped vertical pressure is lost, Factors of diameter and number/types of fittings and length of pipe increase the losses in pressure.....minimizing these loses and getting the most out of your pump is the key. The more fittings, splits, and bends will subtact your pressure due to friction.

If the pump outlet is the lowest point, the "head pressure" loss from gravity is calced from that point to the center of the tallest point it needs to be pumped up to verticaly. Which is your major loss in pressure. To find total pressure loss, we would add in the above friction losses........

Ehhhhh.......lets start there, I tried to answer you questions, but there is a lot that needs to be explained to understand it all......happy to continue if you have any questions and I am sure others will chime in to add........

But in the end, since your looking for an efficient one, that brand that you find will determine what pump rate based on what they offer...........So you may have to resize you plumbing based on the pump? Chicken or egg syndrome.

 

[Jacob D]

You don't need to know the physics of it, you just need to know how to read a pump curve, and use one of the calculators, like this one mentioned above.

When you go to buy a pump look for the curve diagram. Find the intersection of the flow rate (numbers on the bottom) and the head pressure you calculated (numbers on the left). Now find the curve that comes closest to intersecting this point. Most of the time you'll make the decision to either add or decrease the capacity depending on what you're after and the closest matching pump curve.

Sometimes there are other curves overlayed on the diagram as well, but in our hobby it's usually just the single performance curve, which makes it pretty easy to figure out.

 

[dots]

<a href=showthread.php?s=&postid=8432496#post8432496 target=_blank>Originally posted</a> by mothra
You don't need to know the physics of it.

True, but I was trying to answer his questions directly and come closer to understand what is really going on rather than have someone else figure it out. I myself think thats one of the coolest things about this hobby, the vast amounts of biology, chemistry, and physics to understand.....so we can build better tanks......

 

[Justin74]

What kind of connection is a SQWD? Id like to plug that in there, although my overlfows maxed out so I wouldnt be able to upgrade unless I overhauled my whole return system really.

-Justin

 

[dots]

here you go Justin:
http://www.marinedepot.com/md_searchitem.asp

I am sure you have seen them before.

 

[Justin74]

I already have one inline I meant to plug it into the calculator because Im not sure what it's connection would classified as other than " an inexpensive alternative to ball valves..." Sorry to hijack your thread Just been wondering exactly how much I got goin on in there.

-Justin

 

[dots]

I think it all relates, its better than debating stores....he he he.........You "might" be able to do some research and find the manufacturer specs and find out what the parisitic loss is.....I think anything would be a guess for an input. I havn't seen one up close before.....whats in em? a vane?

I was going to add to the above....to really appreciate those calculators one needs to do them by hand at least once........I remember some of the ones I had for homework took about 45 minutes for a simple system by hand, some people were faster than me however.

 

[Jacob D]

For odds and ends like a SCWD you got it - just simplify it to something that you can plug in such as a ball valve, a couple of elbows, etc... It won't hurt to be a little on the high side, maybe 3 elbows even. Not really an exact science, but unless the manufacturer publishes the data you're left doing it this way... or buy a couple of low range pressure gauges and put one downstream and upstream of it to get some data.

 

[dots]

From Marine Depot:

Flow into SCWD SCWD TD Output Efficiency
150 gph 90 gph 60%
180 gph 120 gph 65%
240 gph 180 gph 75%
270 gph 210 gph 80%
330 gph 240 gph 80%
400 gph 360 gph 90%
600 gph 540 gph 90%
720 gph 660 gph 90%

 

[Justin74]

My pumps 850gph so it looks like the trend is about 90% for the higher rates. Nice! Thanks Doug!

-Justin

 

[Jacob D]

That's a little odd... those numbers must be based off of the performance of *a* pump with the pressure drop taken into account... but what pump? That is to say if you want to know what the pressure drop across it is and how it will effect the performance of *your* pump it doesn't tell you. Did they include an pressure data?

 

[dots]

Those are flow numbers through the fitting......with the data measured before and after. Flow is related to pressure.....all that physics stuff you know (sorry couldn't resist), so yes they did indirectly give the pressure drop....and in the Bernoulli equation the Flow rate "Q"=Area of the pipe*Velocity of the fluid, is one metric that can be used to describe the performance, as with Weight flow rate and Mass flow rate. Those numbers show that as the sucker has more pressure it becomes more efficient, thats why Justin was excited about his. That drop in flow rate you see correlates to the loss due to friction through the fitting, hence a drop in pressure where the fitting is located in the system. The drop in pressure you are looking for can be found using Bernoulli's eqn. at before and after the fitting, and yes its a lot of work to find out and they probably should have given us a pressure drop across instead so most could use the data, but the pressure drop across that little fitting is probably very small. In fact the call losses due to friction across fittings "minor losses". I hope those are average numbers from multiple tests using various pumps or else they ain't worth squat, and in addition wouldn't do much credit to Marine Depot for publishing them in the advertisement. But I would assume if you found the company who makes them, I bet they would have that direct pressure loss across. It is interesting however, that that flow loss changes and I am curious to that.....probably they geometry of the internals I would guess.....

 

[raymond4133]

Okay I think I got it ....

I have about 5.36 feet of head pressure for each side of my overflows...For my 2500 Rio it says that I get 432 gph for that amount of head pressure...However I can't calculate the CA 4000 pump since it is not listed...

For both pumps I use 135 watts ....Although, with both I still think I am rather short perhaps a couple 100 gallons if the same goes with the CA 4000 pump that puts out 1300gph...However the Rio 2500 only says it puts out 2972 Liters/hour... I converted the liters perh hour with google calculator and got 785 (O feet head) for my RIo 2500 pump


Above all I would like to try and find a pump (Submersible that I can split between the two overflows and still be able to supply enough pressure for both or in other words at 12 feet head pressure I want to supply 1200GPH or above...If i were to use a ball valve that I can personally adjust and make sure that the water flow is geared to my own specific pump...

-Will using a ball valve mess up the pump or create extra pressure to the pump and cause it to backfire if there is a certain amout of pressure that is pushing back against it (ball valve)
Understandbly if I were to close the ball valve 75 %-100% when the pump is on full blast then wouldn't that cause the pump to perhaps burn out...

-So I guess what I'am trying to say is that what amount or percent will pumps generally burn out when under full blast...I still want to buy a pump that can generate enough gph to supply 1200gph but still be over a little by perhaps 500 gph max...But I will still be able to control that extra 500 gph by reducing the flow with a ball valve until I get the right amount that I need by turing the valve til I'am able to get an equal amount of 1200 gph by a certain closing of the ball valve of a certain percentage....Mostly done with trial and error...

 

[raymond4133]

alright guys/gals...

I have been looking at everything on powerheads and pumps...
And I saw the QuietOne pumps...

Iam thinking of either using two of these (QuietOne 4000 Pump)

Or Splitting a (Quiet One 9000 Pump between the two overflows..) I even calculated according to my information on the head loss calculator and I got around 580-593 I think it said...But that is still pretty close...

- I just think that perhaps this would be a wise choicie as well...

The two Quiet one 4000 pumps would only use a total of 100 watts and the 9000 pump would use 140...I use with my two current pumps 135 watts...


So what does everyone think...Is it a good choice...I just don't want what happend to alot of other people and their experiences with RIO pumps...(with them breaking and letting oil out and killing everything in the tank) I just hope these Quiet Ones are not like the RIos...

-any comments though on the Quiet One pumps...anyone...

 

[Jacob D]

Raymond

Yes if you use a valve to throttle down to the pump 75% it will cause excess heat and vibration and shorten the life. Ideally you want to select a pump that fits the bill for your application. It doesn't hurt to oversize a little; then one solution is to put a divert loop off the discharge side of the pump, which is a tee, then a ball valve, and plumb it back into your sump, refugium, etc... This way the pump can return water to your tank w/o having a huge restriction right in front of it. If it's too much flow just start to open the ball valve on the divert until it diverts enough flow to your satisfaction.

The pumps you mentioned look like they would fit the bill. I have heard good and bad about the Quietone pumps but don't have any personal experience w/ them.

 

[raymond4133]

So what are some people's experience with the Quiet One 4000 PUmps or Quiet One Pumps in general...

I'am really getting into wits end and I would really like to think that the Quiet One pumps are my answers...I hope they are dependable and don't spit there guts into my tank like the RIos have been noted to do...Unless Rio has already fixed that problem...In the new releases of their pumps...(But it seems they have not according to many aquarists )

But, I would really have the piece of mind that these return pumps that I will put into my sump will not fail or mess up on me...

-Another concern is my sump area to put these Quiet 4000 pumps is not so big...Yes I can fit my CA 4000 pump and my Rio 2500 pump but will they be big enough for two Quiet 4000 pumps ...In that area as well I have a in sump CA skimmer as well so space is limited to what I have right now with what I am able to fit with the two current pumps I run...

-Any experience would be greatly appreciated...

thanks raymond

 

[plankton]

Rio 2500 is a perfect pump to mix your salt water before you do your biweekly water change. Don't put a rio in your main tank.

Quiet one pumps are OK, but instead of putting a pair in just get a single industrial quality pump (such as Sequence, etc), then build a manifold so you can route the water where you want (with at least one port going back to your sump as Jake suggests where you can regulate the flow via a ball valve). Unions (full or half) are expensive but very handy when you need to pull a component out.

Scott