Low flow in return line

[jandersen13]

I have 3 return line jets to our pool (and 2 skimmers and no main drain as it is failed). The return line closest to the pump has the fastest flow, the 2nd closest has the 2nd most flow, and then the third is the furthest and has pretty much no flow to it. If I was to rank them on 1 - 10 scale (1 low, 10 high in flow rate) this is how it would go:

1 (closest) - 10
2 (2nd closest) - 6
3 (furthest) - 0 - 0.5

This 3rd return line used to have a higher flow out of it last year and the year before. Any idea why this is not generating water flow from it? The pump PSI stays at 20 normally and has been running at that so far this year consistently. It does creep up as normal and then I backwash but probably only every couple of days (or after heavy usage). I'm hoping someone can help identify some ways to narrow this down to what the issue may be. Any help would be great.

 

[pooldv]

Most pool returns are plumbed on a loop system to equalize pressure around the pool. Maybe yours is not and the last one is at the end of the line and getting less flow.

Since it has gotten worse maybe some debris in the return line from construction has gathered at the end of the line. Remove the eyeball fitting to see if there is debris trapped behind it. You can also try a plumbers snake in the line to see about dislodging any debris.

Once the lines are clean if the issue persists you can put smaller eyeball fittings on the first return so that more water goes the the others.

What I do NOT know is if you can simply remove the eyeball in a vinyl pool same as you can in a plaster pool.

 

[jandersen13]

I should clarify the pool was built in 1983 but I only referenced the last few summers as we just moved in a few summers ago.

I'm guessing the last return is just the end of the line and is weaker but it really seems to have gotten much weaker this year. I did take the eyeball off and reach in and did not see anything clogging it but have not tried to snake it.

Would I hurt water movement in the pool if I put a smaller eyeball on the first return? The first return goes into the deep end (6 feet) and I have it pointing mostly down due to the main drain not working. I didn't want water to get stagnant there.

Also, my PSI has not changed so this doesn't signal to something caught in the pipe right?

 

[pooldv]

That is a reasonable theory, pressure could increase with blocked flow. Changing to a smaller eyeball orifice will reduce flow but increase velocity so it might actually help with movement in the deep end. It will also send more water down the line for the other returns.

 

[jandersen13]

Thanks, I'll give that a try!

Any eyeballs you recommend?

 

[pooldv]

It depends what you have now. Here are a bunch of them for reference.
Wall, Return and Eyeball Fittings.

 

[jandersen13]

Thanks for your help pooldv! I picked up a couple of 3/4 inch eyeball's at the store on the way home today. Put them in and everything looks to be back to normal. It really helps move the pressure to the other return lines. Now I have the 3/4 inch eyeball at the first 2 return lines and a slotted one on 3rd return as it is on the stairs. Would you recommend a 3/4 inch one for the stairs as well or a slotted one like I have now?

 

[pooldv]

Good news, glad its better! Is it horizontal or vertical? Might need a pic to understand that better.

 

[jandersen13]

I have it facing horizontal angled down towards the stair right now. It looks like this:

Hayward SP1419A Replacement Slotted Pool Eyeball Return 1 1/2-Inch Inlet Fitting

 

[pooldv]

I have one of those on the floor of my sun shelf. If that is on the pool wall then I think a regular return would be better.

 

[jandersen13]

Yes, it is on the wall. Makes sense, I'll switch it out. Thanks again!