Thinking of adding returns to AG pool...

[seadogg]

My 16 x 32 AG pool with deep end (15,000 gal.) has one skimmer and one return. I would like to add more return "eyeballs" to get better circulation (One at each end and one on each side – for a total of 4). Is this a good idea and what's the proper way to do it? I'm thinking of running a completely new hose around the base of the pool and teeing off at each return to have them attached in series (and do away with the single short hose going to the one existing return). Could the tees be on the ground with a short hose running up to the eyeball or should the tees be at the eyeball with the main hose rising up to the level of the eyeball and tee for less total hose length? (The first choice would look better but the second choice seems more efficient.)

I was considering putting all at the same level as the original which is just below the surface, but as I write this I'm thinking some could be a little closer to the bottom. Is there any benefit to lowering them and is there a practical limit as to how close to the bottom the returns can be? Since the eyeballs can be aimed, maybe all at same level is best?

The one single return at the deep end seems to work OK, except at the shallow end where the wedding cake steps are. This idea started with adding one return line at the shallow end to help eliminate the algae that accumulates at the steps, with water flow directed at/under them. Now I’m thinking it won’t be much more trouble to add several – if it’s not a wasted effort!

I have a 20” sand filter with 1.5 HP pump motor, which I think should easily overcome any additional flow restriction introduced by the extra hose running around the pool.

I believe this covers everything. Please let me know what you think! I’ve searched the forums in particular and the web in general and can’t seem to find this information.

Thanks

[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

[Watermom]

OK, Sponge. I deleted the posts per your request. There is a window of time where you can edit a post. I do not know how long it is though. Sorry 'bout that!

[Sponge1971]

(this is a re-edit and re-post of a month old previous post, before I even had my pool in hand...)

I *just* bought a 15' round 'pool only' and struggled through spec-ing out the most efficient accessories. I believe it's all about the 2" and searched for info on skimmers and returns for hours...(which brought me to here)
(<sigh>... there's no such thing as a 2" AG return and AG skimmers only come in 1.5". I actually had my skimmer modified. Dr. Plastic Welder welded a 3" ABS hub into the bottom of my skimmer.)

Anyway, I wanted to add my 2% and throw some extra change in there too...

My background, to flavor where my rational is coming from:
I've got a 2year diploma as an Industrial Instrumentation Technician (works good as a table placemat now, though). I've been working as a maintenance technician in a Nuclear Power Generation Plant for 20years, specializing as a Power Operated Valve diagnostics Technician for the last 15-ish years. I have some idea of flow, but not like an engineer would. However, I have the ability to learn...if only I had enough time...<sigh>

..................various comments to all posts above mine:

- re: lower returns could affect winterizing draining obligations...
Am I right here?
Eyeballs can be unscrewed and proper winterizing plugs can be screwed in, blocking all water from entering the pipe. As for the water in the pipe...the seasonal disconnect should cause all that water to drain out of the pipe. So, the pipe is drained and plugged (while still underwater) = no freezing in fitting or pipe.

-re: "Cutting your own can open them up to corrosion..."
Is there not some product (awesome paint) that can be applied to the cut, to protect it?
I did cut my own 2nd return. My pool walls are aluminum, so I didn't sweat any protective coating. (I realise aluminum does 'rust' but it'll take quite awhile before it becomes a problem)

-re: "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."
This is kinda just for the discussion, since I just 'think' I'm kinda smart....but here goes:
Assuming it's 'winterizing safe' to have returns near the bottom and fresh cut corrosion is handled... I think you would lose a lot of 'circulatory power' from a jet trying to blast down through 3 feet of water. The jet would also spread out quickly, so there'd not be much left to stir that last foot of water.
The top water is already being handled buy the upper return. Why even pass through it with a second return that's supposed to be handling only the lower water? If the jet's at the right level...all power is dedicated to just that level of water.
I chickened out on cutting a 'lower' return. I never originally considered the extra pressure on the bottom of the wall, when I suggested cutting a 'lower' return. Seeing all those closely spaced wall joint bolts, at the bottom, kinda freaked me out. Anyway, I went another route...I removed the eyeball from my 'stock' return (next to the skimmer) and screwed in an elbowed 1.5" pipe that runs down to the floor and spits water out along the floor towards the center of the pool. my idea is that the floor flow will go all the way to the other end and roll up the wall...where the 2nd return is. The 2nd return is suface only and acts to push surfce water back towards the skimmer. This would establish a rolling circulation of the entire volume. It sounds good, and I 'can' feel the water flow on my feet, but I'd have to dye the water to really see how it flows/circulates...


Now for some new ramblings:

Here's a puzzler (and why I started looking for return info). My pool has a skimmer and return, right next to each other. Is this because it's cheaper to plumb? I don't see the point of shooting water out and having half of it spin right back into the strainer. I'd have put the return on the opposite side of the strainer. What's the design rational for the manufacturer's placement?

It's all about turnover. Turnover is affected by circulation and good 'stirrage'. You don't want just the top foot of water to go for a ride all the time. If the entire pool could be guaranteed to pass through each run, then turn over rates could be reduced. The only option I see is to install more returns (which I did), to ensure more stir. I want to run 2" anyway and 1 eyeball isn't going to cut it.

I'm actually thinking of having a 3rd small 1" or 3/4" tapoff to feed a 'fan shaped' return (made by Hayward), to stir up the wall behind the ladder. Is this worth it? I don't yet have any experience with cleaning yet...