Thinking of adding returns to AG pool...

[badutahboy]

My only thought/concern is that if you simply add a line and run them in series, you're basically stealing pressure from each return. you may not get the effect you want...

It seems to me that if your goal is to prevent algae from growing near your steps, I'd either only add one extra return so that you're only splitting the water flow two ways (which should keep a fair amount of power for both returns), or add as many as you want, but also add diverter valves so that you can shut down returns in order to maintain some pressure.

[seadogg]

My only thought/concern is that if you simply add a line and run them in series, you're basically stealing pressure from each return. you may not get the effect you want...

It seems to me that if your goal is to prevent algae from growing near your steps, I'd either only add one extra return so that you're only splitting the water flow two ways (which should keep a fair amount of power for both returns), or add as many as you want, but also add diverter valves so that you can shut down returns in order to maintain some pressure.

Thanks, that sounds reasonable. I'll probably add just one or wait and see how the new pump/filter works and then decide. Would I have better flow rate if I put a "Y" on the filter discharge and ran a seperate line to the new return instead of running one hose with two returns in series?

[badutahboy]

Thanks, that sounds reasonable. I'll probably add just one or wait and see how the new pump/filter works and then decide. Would I have better flow rate if I put a "Y" on the filter discharge and ran a seperate line to the new return instead of running one hose with two returns in series?

You'll always have lower flow at the return furthest from the pump... that's just physics... If you want to compensate, you have a couple options:

to run a Y with each line being equal length.. either by moving the pump to the middle of the two returns, or by simply wasting enough hose on the close return to even it out

or you could make the hose going to the return closest to the pump a smaller diameter (IE 1.5 inch hose going to the return on the far end of the pool and 1 inch hose for the return nearest to the pump).. changing to a smaller hose near the pump creates some back pressure on the smaller hose because it's volume is considerably lower, which allows the Y to transfer some extra pressure to the longer hose... It's a trial and error thing to figure out what sizes work best for you.

or you could add a regulator/valve on the shorter line.. by doing that, you can specifically control how much water flows through that return, effectively boosting the other returns flow.

To answer your original question about Y vs Series... I've got no idea if one will result in better pressure than the other. Ultimately, the pump will push more water through whichever path offers the least resistance, which means the shorter hose or nearest hole, unless there's something to equalize the pressure down the line. In my pool, my hoses are all 1 1/2", while the opening in my return is only about 3/4"... so there's clearly some backpressure created there.... I just don't know if it's enough to support a 2nd outlet without a significant loss in pressure.

Ultimately, I would probably not overthink it. Add a single return near your steps, and run it in series like you originally thought... If there's no pressure at it, then check the above steps for solutions... If there's plenty of pressure at both returns, you might be able to put a third return in like you originally wanted... I seriously doubt you'd get more than 3 returns and still have any sort of decent pressure coming from them.

[badutahboy]

One more thought to answer a question from your initial post... maybe someone else can chime in with more details:

If you lower the level of your new return, you're effectively changing how much water you need to drain when you winterize.. remember, you're supposed to drain below your return outlet, so if you put one near the bottom of the pool, you'll have to drain almost all the water out, which weakens your pool structure in the winter.

If you're in a climate where you don't have to winterize, clearly this isn't a problem.. There may also be some sort of workaround if you live in a winter climate, but I can't think what it might be... some sort of patch to keep water out of the return fitting, I'd assume.

[badutahboy]

Ok, one more thought... lol.

Whatever you decide to do, I'd do some trial and error before you ever cut your wall... buy all the hoses and attachments, run them to where you want them, and then toss them over the wall into the pool so you can run them and test their pressure.. That way, you'll know exactly what you're up against, and you won't cut permanent holes until you know you want them.

[CarlD]

I think it's a mistake. It's not that big a pool. I have a 16x40 rectangular with a 5 1/2' deep end and only one return and that's all I need.

If your circulation is poor, you have other problems you need to diagnose and address first.

Most AG pools (like ovals) are built with pre-cut points in the walls for fittings. Cutting your own can open them up to corrosion since the cut isn't finished.

The ONLY think I would consider if I were you, is adding solar panels as the "excuse" for a better-located return.

In general, returns should not be low. If you want them to move lower water, you put in a movable eyeball and point it down.

[seadogg]

Thanks for the replies - all good info.

For now I'm going to see how the new pump/filter works - if it's OK, I'll leave it as is.

When/if I need to add another return I'll take your advise and add only one using the pre-cut return hole in shallow end that is currently blocked off.

I also like the idea to add a flow-control valve at the closest return!

Thanks again, Jim