Hydraulics for a 15x35 with some features, some advice?

[Sammy0815]

Hi guys,

I hope that someone can help me a bit in regards to my planned plumbing, in short, the pool is:
- 15x35, 15,000 gallon
- 2 skimmers (on two 2" pipes)
- 4' water descent (on one 2" pipe)
- 2 deck jets (on one 1" pipe)
- 2 bubblers on sun shelf (looped on one 2" pipe)
- 4 return jets (on one 2" pipe)
- 1 main drain (on two 2.5" pipes)

Important:
I am fine with having only 1 or 2 water features running at the same time.

Question:
Can I go with a single 3HP pump or would you go with 2 pumps?
(According to my math, a single 3HP pump would just be fine, but I am afraid I was missing something)

Thanks so much,
Sammy

 

[mas985]

I hope that someone can help me a bit in regards to my planned plumbing, in short, the pool is:
- 15x35, 15,000 gallon
- 2 skimmers (on two 2" pipes)

I would make the skimmers 2.5" lines. Skimmers can often clog and having a larger line can prevent that. Plus, the larger pipe would allow you to operate one skimmer at a time should the need ever arise.

- 4' water descent (on one 2" pipe)
- 2 deck jets (on one 1" pipe)
- 2 bubblers on sun shelf (looped on one 2" pipe)

GPM Requirements?

- 4 return jets (on one 2" pipe)
- 1 main drain (on two 2.5" pipes)

Important:
I am fine with having only 1 or 2 water features running at the same time.

Question:
Can I go with a single 3HP pump or would you go with 2 pumps?

(According to my math, a single 3HP pump would just be fine, but I am afraid I was missing something)

So why did you not show your work?

Sizing a pump by THP is big mistake. Not all pumps have the same performance even though they might have the same THP.

So which pump models are you actually looking at?

 

[Sammy0815]

More information:
- Skimmer lines are already laid at 2"
- 4' water descent (on one 2" pipe): 60 GPM
- 2 deck jets (on one 1" pipe): around 15 GPM total
- 2 bubblers on sun shelf (looped on one 2" pipe): around 25GPM total

Pump chosen: Pentair Intelliflo3 3HP

My math was round about:
60GPM waterfall + 15GPM deckjets + 25GPM bubblers = 100GPM for water features (but again, I am fine with running only 1 or 2 at the same time)
I neglected any friction admittedly, thinking that a roundabout "works" or "you need a second pump" would be fine.

Hope this helps.

 

[mas985]

Distance from pool to pump?

 

[Sammy0815]

Distance from pool to pump?

55 feet

 

[mas985]

The deck jets on the 1" line might be the limiting factor because proportionally, they will have more head loss (~2x) than the other lines even though the flow rate is lower. I would have gone with a larger line for those so that balancing the flows would be a little easier. As it stands now, you will need to restrict the flow on the other lines in order to get the proper flow to the deck jets but it may still be possible to run all 3 features at the same time but probably not the pool returns with it.

 

[Sammy0815]

Awesome, thats what I was thinking too and it helps when someone shares that opinion.

Btw, my plumber set the pipes at the Equipment pad in a way that was suited for a 2 pump configuration.
Like from left to right:
Jets---Bubblers----Main Drain 1----Waterfall----------------------Main Drain 2----Skimmer 1-----Skimmer 2-----Return line
(he assumed the first 4 go on one pump and the second 4 go on the other pump)

In other words, to now just put 1 pump on it will require a couple of elbows more than expected.
Should I worry and or is that ok?

 

[mas985]

The elbows won't cause an issue.

 

[pjt]

You'll be fine with one pump, especially if you're willing operate 1 or 2 water features at a time. You'll likely use your water features less than you currently think.

I operate my entire system (water features and normal returns) with one pump, and it works great.