3/4" vs. 1" return eyes make a difference?

[mihzyd777]

Hello,

Trying to find ways to lower my filter pressure. I only have 4 returns and soon to have 5 as I am adding the suction cleaning pipe as another return. The PB used 3/4" eyes. If I change that to 1" eye returns will it make much of a difference?

Thanks!

 

[Jimrahbe]

M,

I'd think you would get a noticeable difference, although not sure how much.

Best way to bring your filter PSI down is to run a VS pump at a low RPM.. My filter pressure is about 1 or 2 lbs..

Thanks,

Jim R.

 

[wcharon]

I have a similar question and hope OP doesn't mind.
I only have 1 return with 3/4" eye. I am trying to stir a little more the bottom for debris removal thru skimmer. I have played with the eye position and it works best at a 45 degree angle opositive to the skimmer.
If i change the eye 1" do you think i will get more flow output to achieve my goal?
Thanks in advance and once again sorry OP.

 

[sktn77a]

Yes,mihzyd777, it will reduce the pressure some at the expense of velocity (the force of the water at the eyeballs will seem lower).

 

[mihzyd777]

Yes,mihzyd777, it will reduce the pressure some at the expense of velocity (the force of the water at the eyeballs will seem lower).

The water will lose some velocity but because there is more coming out will it move the same amount or more on the surface?

Thanks all!

 

[mihzyd777]

M,

I'd think you would get a noticeable difference, although not sure how much.

Best way to bring your filter PSI down is to run a VS pump at a low RPM.. My filter pressure is about 1 or 2 lbs..

Thanks,

Jim R.

I do run it low for filtration and getting around 4 lbs. however my concern is more with when I'm running at 35-40gpm so that I can run the heat pump and I'm registering 12 -14 lbs. of pressure on the filter.

 

[Jimrahbe]

when I'm running at 35-40gpm so that I can run the heat pump and I'm registering 12 -14 lbs.

M,

That sounds perfectly normal to me...

The faster you run the higher the pressure will be...

Pools with a single speed pump will run 20 to 30 PSI..

Thanks,

Jim R.

 

[mihzyd777]

M,

That sounds perfectly normal to me...

The faster you run the higher the pressure will be...

Pools with a single speed pump will run 20 to 30 PSI..

Thanks,

Jim R.

Man I wish I took video or picture with on my old pool. I could have sworn my piping was so efficient that I would be lucky to register 1 lb. on my filter at 35 gpm.
If I can ask what rpm or gpm do you run at and what is your wattage on your pump and filter pressure?

Thanks!

 

[Jimrahbe]

M,

I run my 3 HP IntelliFlo at 1200 RPM, most of the time.. At that speed my filter pressure is about 1 or 2 lbs. Keep in mind that I have a large cartridge filter (CCP-520) and a 30 lb. gauge so I can see one lb. At that speed the power used is 170 watts. Newer IntelliFlo pumps use even less wattage then mine.

I have no heater and my water feature is not normally running.

Heaters, plumbing, in-floor cleaning systems, and the size of the filter all play into how much "pressure" the filter gauge will show..

Thanks,

Jim R.

 

[markayash]

You can just remove the eye and see if that changes your pressure. I have tried both and a slight difference between in pressure

 

[mas985]

Trying to find ways to lower my filter pressure.

Why?


Here is a comparison of the two eyeball sizes:

Parameter	Scenario 1	Scenario 2
Orifice Diameter (in)	1​	0.75​
Orifice GPM	10​	10​
Axis Distance (ft)	10​	10​
Off Axis Angle (deg)	10​	10​
Orifice Exit Velocity (ft/sec)	4.09​	7.26​
Orifice Velocity Head (ft)	0.26​	0.82​
Center Line Velocity (ft/sec)	0.211​	0.281​
Off Axis Velocity (ft/sec)	0.0193​	0.0257​

There isn't a big difference in the velocity head between the two orifices compared to the overall head loss in the plumbing so the total flow rate and the flow rate for each eyeball won't change much. However the velocity in the pool (center line and off axis) is substantially different (~30%).

 

[mihzyd777]

M,

I run my 3 HP IntelliFlo at 1200 RPM, most of the time.. At that speed my filter pressure is about 1 or 2 lbs. Keep in mind that I have a large cartridge filter (CCP-520) and a 30 lb. gauge so I can see one lb. At that speed the power used is 170 watts. Newer IntelliFlo pumps use even less wattage then mine.

I have no heater and my water feature is not normally running.

Heaters, plumbing, in-floor cleaning systems, and the size of the filter all play into how much "pressure" the filter gauge will show..

Thanks,

Jim R.

Do you actually see the returns working and pushing the water at that RPM?

 

[mihzyd777]

Why?


Here is a comparison of the two eyeball sizes:

Parameter	Scenario 1	Scenario 2
Orifice Diameter (in)	1​	0.75​
Orifice GPM	10​	10​
Axis Distance (ft)	10​	10​
Off Axis Angle (deg)	10​	10​
Orifice Exit Velocity (ft/sec)	4.09​	7.26​
Orifice Velocity Head (ft)	0.26​	0.82​
Center Line Velocity (ft/sec)	0.211​	0.281​
Off Axis Velocity (ft/sec)	0.0193​	0.0257​

There isn't a big difference in the velocity head between the two orifices compared to the overall head loss in the plumbing so the total flow rate and the flow rate for each eyeball won't change much. However the velocity in the pool (center line and off axis) is substantially different (~30%).

Do you think my wattage at 30gpm is OK?

 

[Jimrahbe]

M,

At that speed I am moving enough water to close the flow switch on my SWCG.. So my guess is that is about 20 GPM... At that speed my Skimmer work just fine.. Unlike a single speed pump, you will not see a lot of "action" when looking down into the skimmer.. That said the speed of the pump is not what makes skimmers work, it is the weir door.

I have my returns pointed level or maybe just a tad down, so I don't see a lot of surface motion, but yes, I can tell the pump is running by looking at the surface water.

What HP pump do you have?? My IntelliFlo is a 3 HP pump.. and keep in mind I do not have a heater.

Thanks,

Jim R.

 

[mas985]

Do you think my wattage at 30gpm is OK?

It depends on the pump model. But an Intelliflo on typical 2" plumbing would have an operating point of 70 GPM & 1037 watts at 2429 RPM so significantly different than yours. At 30 GPM/1035 RPM on the same 2" plumbing, the Intelliflo would use about 152 watts so much less than your pump. But it probably isn't the eyeballs. List out all of your equipment and plumbing (sizes and lengths) and maybe we can spot the problem. The more details you can give, the better. Pictures of the equipment pad would help too.

 

[mihzyd777]

M,

At that speed I am moving enough water to close the flow switch on my SWCG.. So my guess is that is about 20 GPM... At that speed my Skimmer work just fine.. Unlike a single speed pump, you will not see a lot of "action" when looking down into the skimmer.. That said the speed of the pump is not what makes skimmers work, it is the weir door.

I have my returns pointed level or maybe just a tad down, so I don't see a lot of surface motion, but yes, I can tell the pump is running by looking at the surface water.

What HP pump do you have?? My IntelliFlo is a 3 HP pump.. and keep in mind I do not have a heater.

Thanks,

Jim R.

Hi Jim,

I have the new Intelliflo VSF like you it's also 3hp. When I switch between GPM & RPM and I enter 1200 RPM I barely feel any water coming out of return.
It's interesting that you mentioned the weir door. I had 2 skimmers put in and don't have a weir door on any of them? This is a new pool build. What does the weir door do that helps?

Thanks!

 

[mihzyd777]

It depends on the pump model. But an Intelliflo on typical 2" plumbing would have an operating point of 70 GPM & 1037 watts at 2429 RPM so significantly different than yours. At 30 GPM/1035 RPM on the same 2" plumbing, the Intelliflo would use about 152 watts so much less than your pump. But it probably isn't the eyeballs. List out all of your equipment and plumbing (sizes and lengths) and maybe we can spot the problem. The more details you can give, the better. Pictures of the equipment pad would help too.

So my bad that screenshot was before I removed the spring in the Crud check valves that I have coming off heater as the heater manufacturer AquaCal said I need one or it voids the warranty. That being said this is a all new pool that just came online 3 weeks ago. Here is my equipment and piping:

*Intelliflo VSF - pull from 2 skimmers (1 skims only, Other skimmer can skim or pull from dual main drains in 8ft deep end. The skimmers do not have weir doors on them is this ok?
* 2.5" pipes coming from each skimmer separately
*2" pipe from out of pump to Pentair Quad 100 DE filter with backwash valve (which I wonder can be causing some back pressure), freshly added ZeoFiber which I've used for 10 years on our old pool.
*Out from Filter 2" to AquaCal SQ 225 heater that has a diverter in case water goes above 70gpm.
*Out from Heater 2" to Check Valve (which I recently removed spring and it helped big time as you can see). Then to IC40 then into ground.

Here is where it gets interesting and I'm hoping this is not where my issue is. The 2" return goes underground from equipment to pool about 20' ft has a right turn 90 sweep to go right then another 90 sweep to go up to a PVC "T" that is also 2" then from there is it downsized to 1.5" pvc and one side goes to 2 returns about another 20'ft run with 3/4" eyes and then also goes right to 2 more returns about 30'ft run as well also 3/4" eyes. 4 returns total. I do have a vacuum pipe right next to this that I circled in the attached pic that I will be asking the pool builder to connect as a return as well with a valve to control flow. Is this a good idea?
I've also attached a pic of my check valve and you can see the spring and flap I remove to help lower the pressure. There eis a pic of my filter pressure when running my Intelliflow VSF @ 30gpm.

Thanks for the help!

 

[Jimrahbe]

M,

1200 RPM on my pool is about 1600 or more on pools with heaters.. And to make matters worse, you have a DE filter with MPV which adds even more back pressure.. I have a large cartridge filter which has no MPV valve..

Well, without weir doors you do not have skimmers.. What you have is two open lines back to the pump..

The weir door is what makes the skimmer... well, SKIM. With a weir door the surface water is skimmed or removed from the pool.. Without the weir door the surface water just floats there and the pump sucks water from the bottom of the skimmer pot.

Without a weir door your "non-skimmer" is about half as efficient as it should be at removing floating debris.

Any pool builder that removes the weir door just has no clue how a pool circulation system actually works.. Sigh!!

Thanks,

Jim R.

 

[Jimrahbe]

M,

Show me a close up of the heater by-pass set up you have...

Thanks,

Jim R.

 

[mihzyd777]

M,

1200 RPM on my pool is about 1600 or more on pools with heaters.. And to make matters worse, you have a DE filter with MPV which adds even more back pressure.. I have a large cartridge filter which has no MPV valve..

Well, without weir doors you do not have skimmers.. What you have is two open lines back to the pump..

The weir door is what makes the skimmer... well, SKIM. With a weir door the surface water is skimmed or removed from the pool.. Without the weir door the surface water just floats there and the pump sucks water from the bottom of the skimmer pot.

Without a weir door your "non-skimmer" is about half as efficient as it should be at removing floating debris.

Any pool builder that removes the weir door just has no clue how a pool circulation system actually works.. Sigh!!

Thanks,

Jim R.

Oh man. So I just sent a message to my PB asking him to put weir doors in. He has been good so far so we will see how that goes. As for the Multi-Port valve.....ya I'm not liking it much and will remove it. I prefer to remove my filters and wash them down instead of backwash. How much pressure do those cause any idea??

Thanks for the help!