Return Eye Sizes

shep377

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Jun 27, 2012
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#1
I have read in posts here about people wanting to get larger return eyes to lower friction loss and move more water... my pool eyes came with the eye and 2 sets of inserts that snap into the back to change the size of the eye discharge. I get that a smaller discharge would give a more powerful jet to circulate water in pool, but it would also create more back pressure.

I was thinking of removing the inserts all together to get the biggest opening I can (still with the eye face on, just without any little cones to make it smaller). Any reason why I wouldn't want to do that? Actually, I was thinking I might improve the efficiency of the entire system by removing them.

Cheers.

Josh
 

Bama Rambler

Mod Squad
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Jun 23, 2009
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SouthWest Alabama
#2
There are reasons to increase the backpressure on the system (i.e. install smaller eyeballs), however it's extremely rare to need to do that. If your plumbing was so efficient that it allowed your pump to run beyond it's curve you'd want to restrict it a little. I'm sure they exist, but I've never seen a system that was that efficient.

Given that, I can't see a reason not to remove all the orifices and allow the greatest flow.
 

elwood58

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May 3, 2012
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Sun City West Arizona (2nd Home)
#3
The greatest flow is great for filtration, but may not be the best solution for getting stuff into the filtration loop. Higher pressure may have an overall cleaning benefit from two perspectives:

1. Stirring up stubborn bottom dirt.
2. Creating the circular flow that many/most skimmers like.
 

mas985

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May 3, 2007
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#4
Increasing eyeball size has two effects. One is the lower head loss as was mentioned. But it will also decrease the water exit velocity (ft/sec) from the eyeball. So this can have an effect on the water surface velocity if that is necessary to keep your skimmers working well. However, if you have a lot of eyeballs, the change in both head loss and exit velocity may not be significant enough to notice.

One more thing I forgot to mention is that even though increasing the size of the eyeball reduces head loss, if you don't reduce pump run time, you will end up using more power and not less. This is because as head loss drops, flow rate increases but so does pump energy just not as much. So if you don't change pump run time, the pump will end up using more energy.
 

shep377

LifeTime Supporter
Jun 27, 2012
79
0
#5
Ok... I think. Right now I am running the pump typically from 9am to 6pm, to be circulating in the daytime heat, and also turn it on when people are in swimming outside that. I have my Salt Gen set at 50% for that time and it seems to be starting to work. (just been up and running a few days so far...)

I have 2 eyeballs. If I change the eyes to bigger openings, then I would see the filter gauge drop from 12-13PSI down. If it only drops it slightly, say 1 PSI, then I would think that the lower head pressure would be a good thing? Conversely, if putting the smaller plugs in raises it 1, then should I do that and as you say, decrease the energy the pump uses. I think I am circulating all my water in 8h so time should not be a factor...

Is nothing simple?!??
 

JasonLion

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May 7, 2007
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Silver Spring, MD
#6
In most cases the best thing to do is to use larger eyeballs and reduce the pump run time. That will lower the filter pressure and save electricity.
 

mas985

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May 3, 2007
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Pleasanton, CA
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#8
shep377 said:
If it only drops it slightly, say 1 PSI, then I would think that the lower head pressure would be a good thing?
It depends on what you mean by a good thing.

If you ONLY change the eyeballs to 1", flow rate will go up slightly and energy use will also go up but by a less percentage. So you are getting more flow rate per watt but if you do not reduce run time, your energy bill will also go up.

I think I am circulating all my water in 8h so time should not be a factor...
Oh, but it is a big factor. The higher your flow rate, the less time you need to run the pump. So as Jason pointed out, if you want your energy bill to go down you have to do two things. Increase the eyeball size AND reduce run time.
 

shep377

LifeTime Supporter
Jun 27, 2012
79
0
#9
:hammer: Ok - I am suitably impressed.

There must be a starting point to all this... something like:

Pool Size
Estimate of flow rate
calculate rough time to cycle all the water in your pool 1.5 times
Run the pump that long...

Do you then keep decreasing the length of time the pump runs until a) your chlorine level starts to drop (salt system) or b) the filtering is not keeping the pool clean?

I'm just new so I am searching in vain for a "this is how you should do it" answer, where there isn't one...

Thanks all.
 

mas985

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May 3, 2007
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Pleasanton, CA
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#10
Minimum run time of the pump should be based on two primary factors; Chlorination and cleaning.

Chlorination/Circulation: This is the most important and if you have a small SWG, this could indeed dictate run time. You must maintain a minimum FC level no matter what.

Filtration/skimming/cleaning: This is mostly cosmetic meaning you can run as little as you want but at some point the pool will "look" dirty. It is a matter of what you can tolerate.


This year, I am running an experiment of sorts. I am running my pool 4 hours per day (1/2 turn/day), 2 hours high speed and 2 hours low speed, with my SWG set at 90%. So basically, my run time is being dictated by the SWG alone. I don't really care if the pool stays super clean, although so far it has been pretty clean. Also, since I use a solar cover, skimming is not an issue so really it is the vacuum cleaner which is doing all the cleaning and two hours per day (pump high speed) seems to be enough to keep the bottom relatively clean as well as keep the pool warm with solar. The additional 2 hours on low speed is for chlorination alone. I also augment the cleaning with some additional manual run time when needed.
 

JasonLion

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May 7, 2007
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Silver Spring, MD
#11
Using flow rate to guess at pump run time is simply a rule of thumb to get you in the right range. It is also often difficult to figure out your flow rate.

What really matters are the two factors mas985 mentioned. There is a good article in Pool School on figuring out your ideal pump run time. In nearly every case it is much shorter than you think it is.
 

shep377

LifeTime Supporter
Jun 27, 2012
79
0
#13
One last question on this... and I have been searching in the forums, found lots, but not able to put it all together:

Watching my filter gauge, it normally sits at 12PSI. I have been told to backwash if it climbs to 20-22ish. If I turn on my deck jets, increasing the friction loss, normal moves from 12 to 17 (adds 5PSI).

If I were to ever add a solar system, I am sure that turning it on would add a jump of perhaps 10PSI to all of this when running
My question is, at what pressure reading do I need to worry about damaging my equipment? I assume that keeping it lower decreases strain on everything along the way (unions, glue joints, etc...), but where will I start to cause damage to pump, filter, SWG, other???
 

TonyM

Well-known member
May 11, 2012
85
0
Middle Tennessee
#15
Hate to revive a very old thread, but didn't want to start a new one for this very similar question...

I currently have a 'darkbuster' pool light as one of my 2 returns on my AGP. The light is blown, it leaks and we never use a light anyway so i am swapping it out for a regular return (which is what I have on the other return). I am getting ready to dive down and look at the lower return, but im guessing it to be a 3/4 eyeball from looking at surface level.

I'm not sure what size the actual return is on this light, so should I just make sure both eyeballs are the same size, or should I put a 1" on the new return and leave the other one alone? I currently have a 1/2 eyeball in my possession that is unopened - i could use that or swap it for whatever is best.

Currently, im running just shy of 10# of pressure just after a BW.