Help with pipe sizing please

DIYCypress

Member
May 1, 2019
8
Texas
Sorry for the double post. I couldn't figure out how to move it.

Completely new construction and looking for help sizing the plumbing/pumps accordingly. I am planning on all Pentair equipment, most likely Pentair 011018 variable speed pumps, 1 main/spa pump and 1 water feature pump. I am using dedicated Paramount 360 Unblockable drains (which suggest a 2.5" minimum plumbing run) and 2 Paraskim Venturi skimmers (which require 2" suction, 1.5 venturi return). Pentair 520 square foot cartridge filter with up to 150GPM flow. Pool is roughly 650 square ft, 18500 gallons, geometric with 7.5 deep end. I want to use the Spa while also using the water feature. The spa is slightly oversized and I am trying to figure out how many jets I can plumb in the spa. Planning on 8 individual waterway jets with a 2" water loop, 1.5" air loop in the spa and two 3 jet manifolds for 14 total jets at around 10-12 GPM ... knowing that I will probably have to close off either the individual waterways or the manifolds to get proper flow. There will be an air blower as well.

1) If I run a 3" suction/3" return to spa and then reduce to 2" looped in the spa, what is the max number of jets I should use at a time? Any issues with plumbing like I described above and only using max number at a time? Thought is to have 3 jet manifold for wife and I and then singles for when we entertain.
2) Planning on running 2" suction from each skimmer and probably 2.5" main.
3) On the returns, my last pool was horribly balanced. I have no idea how it was actually plumbed as it was 10+ years old. With using the venturi skimmers I want to be able to control the return flow to them so at a minimum I plan on running a dedicated 2" return to the set of skimmers and T to the middle of the two using 1.5" pipe (what is recommended by Paramount). For the regular returns I plan on plumbing two other sets of 2" then T to 1.5", 1 set to shallow end and 1 to deep end, all with valves. Then a 2" valved spa return. Is that complete overkill? The difference in cost is minimal in the grand plan but is a simple 2" looped return actually better?
4) Water feature I have a 90GPM for a six foot water feature and then 2 water bowls at approximately 15gpm each. I was planning on running a 3" suction, and then 3" return to the 90gpm and 1.5" to each of the 15gpm, all valved off a dedicated pump. I may also add a couple bubblers but we haven't decided on that but was thinking two 1.5" bubblers on a 2" run.
5) 1.5 Polaris Booster pump
6) 3/4" auto water level

Just basing this off the flow capable of PVC size without calculations for head loss. Spa suction is roughly 35feet from pad which flows in to deep end.

Any suggestions on plumbing size/suggestions I am all ears.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,430
Pleasanton, CA
1) If you had a dedicated spa jet pump, you might get 120 GPM out of the pump. With the filter and heater, more like 100 GPM total. So if they truely are 10 GPM jets (i.e. 1/4" orifice), then you could get up to 10 running in your configuration.

2) I would go with all 2.5" on the suction. No reason not but a lot reasons to do it.

3) Loops don't buy you much around the pool especially with small pipe. If equal flow is the goal, just go with larger pipe. It minimizes the pressure differential between returns.

5) Why not go with a robot instead?
 

DIYCypress

Member
May 1, 2019
8
Texas
1) If you had a dedicated spa jet pump, you might get 120 GPM out of the pump. With the filter and heater, more like 100 GPM total. So if they truely are 10 GPM jets (i.e. 1/4" orifice), then you could get up to 10 running in your configuration.

2) I would go with all 2.5" on the suction. No reason not but a lot reasons to do it.

3) Loops don't buy you much around the pool especially with small pipe. If equal flow is the goal, just go with larger pipe. It minimizes the pressure differential between returns.

5) Why not go with a robot instead?
1) Thats about the max I would expect. Has anyone installed extra jets knowing some will have to be closed to get proper flow?
2) 2.5" over the 3" on the spa suction? Why is that? Does the pad plumbing restrict to much to make 3" not worth or? Or were you referring to main and 2 skimmers?
3) Does running 2.5" pad plumbing make a large difference?
4) Considering the venturi skimmer I'm going to run dedicated returns with valves. Its a little extra work but have the option of balancing as needed.
 

DIYCypress

Member
May 1, 2019
8
Texas
1) Thats about the max I would expect. Has anyone installed extra jets knowing some will have to be closed to get proper flow?
2) 2.5" over the 3" on the spa suction? Why is that? Does the pad plumbing restrict to much to make 3" not worth or? Or were you referring to main and 2 skimmers?
3) Does running 2.5" pad plumbing make a large difference?
4) Considering the venturi skimmer I'm going to run dedicated returns with valves. Its a little extra work but have the option of balancing as needed.
And not doing a robot as I don't like the idea of having to put in and take out. In our old pool we liked the option of leaving it in the pool all of the time and only removing when we would go swimming.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,430
Pleasanton, CA
1) I'm not sure but I can almost guarantee that if you add more jets, at some point you will want them all to run at the same time. You might be better off designing the system so you can do that.

2) That was a reference to your #2 in the first post:
2) Planning on running 2" suction from each skimmer and probably 2.5" main.
3) Not that much. There is usually not enough pipe and fittings to make that much of difference. Most of the pad head loss is going to be in the filter and heater. One way to get more flow rate with that setup is a partial bypass around the filter and heater for running in spa mode. Also, a bypass helps reduce problems on high flow rate with the heater and filter.

4) That's fine but there is a potential issue with that if you have all the valves open. The return head loss can become too low causing problems on the suction side of the pump (e.g. air leaks and cavitation). You just have to be aware of the problem and compensate if it occurs.

As for the robot, mine stays in the water pretty much all the time. It has a weekly timer so I take it out once a week to empty it and of course when we swim. So that is no different.
 
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