Building a brand new pool in Nicaragua

[Halle]

Saluda de Nicaragua!
I will be building a new pool, starting in January, 2014. I'm now in the process of figuring out the mechanics of the pool, pump, filter system and the layout of the suction lines and return lines. This is my first time doing anything like this. I am essentially acting as the general contractor for this project. The pool will be about 51,000 gallons in size, rectangular in shape, 60' long by 20' wide, with the deep end making up 17' of the total length and being about nine feet deep. The rest of the pool will be about four feet deep. There will also be an attached jacuzzi/spa with either four or six jets which will drain into the main pool. I have decided to not have a main drain but will instead have three skimmers, each with its own run back to the pump and each with its own valve. I will have seven return lines, two in the deep end pointing towards the opposite end of the pool where the skimmers will be located, one in the jacuzzi/spa (in case the jets are not turned on), the others located in the four foot deep area. The total surface area is about 1200 square feet. At this point, I am looking at using a variable speed 3HP Pentair Intelliflo pump which is capable of 160 GPM. The filter will be a Pentair Clean and Clear 520 square foot cartridge filter, which can handle up to 150 GPM. For an eight hour turnover, I would be looking at around a 106 GPM flow. For a six hour turnover, I would be looking at around a 141 GPM. I will have a dedicated, valved, suction line to run an automatic pool cleaner. The pool will be an in ground, reinforced concrete, "salt water" pool. There will be no pool heater. This pool will be used mostly by the kids that live in and around us, up to four hours a day, four to five days a week.
In my perusing of different pool sites, pool pump charts and water flow charts in relation to pipe diameters, it looks as if larger pipes are always better, as the pumps don't need to work as hard when either pulling and/or pushing water. If that is the case, why don't more people go to 2 1/2" or even 3" suction and return lines? Generally you get more GPM with less TDH meaning less electricity used. I'm willing to spend the extra $$$ to upsize to larger water lines and lower the TDH as this seems to be worth the cost. Here in Nicaragua, I have paid as much as 44 cents (U.S.) per kilowatt for our electrical power. The more power we use each month, the more we pay. We have the most expensive electricity in Central America. Lucky us! So, keeping our power consumption down with this pool is quite important to us.
MY QUESTIONS:
1) With the jacuzzi/spa do you think that I can run six jets in there while the pump is also pulling water from the three skimmers and returning that water to the pool? How about four jets instead of six as another option?
2) Do you think I should use four skimmers instead of three skimmers?
3) The Pentair Intelliflo pump has 2" inlet and outlet openings. If I go with larger diameter pipe, say 3", should I be looking for a pump that offers larger diameter openings?
4) What are the ramifications of running 3" lines from the skimmers to the pump and then having to downsize to 2" just before entering the pump? Do skimmers even exist that have 3" connectors?
5) Return lines - 3" lines, downsizing to 1" at the pool wall? What are the ramifications of coming out of the pump with a two inch line and then upsizing to three inches shortly thereafter?
6) If I run a return line off of the main pump for the jacuzzi/spa for the six or four jets, what size pipe should that be so that I get enough pressure for the jets?
That's probably enough to start with. Thank you in advance for any insight anyone can share.

 

[FamilyGuy]

Someone with more knowledge will be along. But i think your correct in running larger lines even if they step down in size at your pump skimmers and returns

 

[jblizzle]

Welcome to TFP!!!

Wow that is a big pool. The first thing you need to realize is that "turn-over rate" is meaningless. There is not required amount of turn over each day. See the article in Pool School here: pool-school/pump_run_time

The next thing that jumps out at me is the filter size. We generally recommend filter sizes based on the pool volume. These would be a minimum of:
740 sqft cartridge, 9.3 sqft (41" diameter) sand, 138 sqft DE
But I am not sure what you can find that is bigger than the CC 520, unless you start looking at commercial stuff.

You are correct that large pipe will allow great flow rates, but, having higher flow rates is generally not needed and it costs more to run the pumps at the higher RPMs. Electric pumps are a little odd in terms of the power used, but generally the more water you move, the more power required. In a high head loss system, you will actually use less electricity because you are moving less water.

In reality, when running in general filtration mode, you can run the pump at a very low speed. But, then for the spa you would want to increase the RPM to give greater flow for the spa jets.

So on to your questions:
1) So you have no plans to be able to heat the spa? If you do (or might in the future), you need to have a separate drain in the spa so you can isolate it. With the intelliflo, you should be able to run 6 jets, just use a little larger pipe.

2) Most pools only have 1 skimmer. With a pool that size, at least 2 is likely a good idea, but to me 4 seems like overkill.

3) The more pipe of larger size, the lower the head loss. Just use adapters whenever you need to change size

4) As said before, just use adapters to fit to the equipment. There are no major ramifications.

5) See above.

6) See below.

While I am not a hydraulics expert (maybe Mark will chime in), here are my gut feels for what pipes you should use:
- On the suction side, use 2" pipe to all 3 skimmers. Since they will all be plumbed separately to the pump, that is a LOT of pipe area for the suction side (that is 9.42 sq-in of area)

- How are you plumbing the pool returns? All separately? If so, then 1.5" pipe to each would be plenty. If you are going to plumb a loop and Tee off to the each return, then the loop should be maybe be 2.5" or 3" and then reduce down to each return.

- For the spa returns, you will likely be plumbing a loop and the Tee off to each jet. I would think this run and loop should also be 2.5" or 3" pipe

I would seriously consider having a drain in the spa that would allow you to isolate it and heat it in the future if so desired. For that suction line, 3" would be a good idea.


BTW: I am going to move this into the Pumping Station since that seems to be the main focus.

 

[Halle]

Thank you Jason! This is great to have some real input into this specific project. Here in this part of Nicaragua, we may hit 70 degrees at night, a dozen times all year. It's often hot here and certainly always warm. So heating a spa is not our concern. We are just looking for a place to sit and enjoy water jet pressure on our backs.
I am going to plumb a complete loop around the pool for the pool returns, Teeing off and then reducing into each 1.5" stub out in the concrete wall. I think I'll use a 3" main trunk line.
POOL RETURNS - Any suggestions on how many returns to put in the pool? I keep going back and forth on this... I have been thinking of putting in seven; now three in the deep end, one on both long walls in the four foot deep area, one on the end of the pool opposite the deep end and one in the area of the steps that enter the pool. So along with the six jets in the spa and three skimmers, is this more than the pump can handle? I want to make sure that I get good water movement in the deep end, hence the reason for three in there and moving the water towards the opposite end where the skimmers are located. I'm willing to cut the number of spa jets to four if this would dramatically increase the pressure at the eyeball returns.