Design/Plan/DIY Build NorCal pool

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
I believe one of the last missing parts of my plan is underwater lighting. For a 18x36 rectangular pool with a deep end of 8', what is the recommended number of lights and their location? I'd say two, right? If I go Pentair with the rest of the equipment sounds like "Pentair IntelliBrite 5G Color LED" might be a choice that fits with the system.
 

bmoreswim

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For the lights, two is good. I'd skew them about 1 foot each towards the deep end. That end sucks up light. On the long side facing away from house/primary seating area. The lighter the liner, the brighter the pool. It doesn't matter much on white or light blue, but with some other colors, the pool might not be overly bright with a medium or darker liner. I agree on the lighting equipment selection.
 

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
For the lights, two is good. I'd skew them about 1 foot each towards the deep end. That end sucks up light. On the long side facing away from house/primary seating area.
I believe my wife wants a medium-darker liner so I shouldn't skimp on lighting power. I read multiple times your post and I tried to understand the best combination, but I am still not quite sure :) Which "letter" (A, B, C, ...) position and side would you choose in the following drawing? As it is indicated, the primary seating area in the evening will be on the right. The house has a large glass door facing the pool.

1585259700176.png
 

bmoreswim

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House side. My lights aren’t spaced like I thought. They are 10’ from either end on 38’ long. Deep end I would go 10’ and shallow end 12’ from the ends. Unless you want lots of light then go with three or like 5 small nicheless ones. I’m not sure of 5 for sure but something like that. Or two bigs as above and one nicheless between them.

If you did three big lights, it would be 8’ deep end, 10’ shallow end and then split the difference. But hopefully you could dim them because some colors may be a little too bright.
 

bmoreswim

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Ok slight re-think. I just saw your patio and evening seating. I might go with the higher quantity of nicheless lights on the house side because you have two main viewing areas. House side and right side / right side far corner. The nicheless will give much less glare.
 

ajw22

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Jul 21, 2013
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Ok slight re-think. I just saw your patio and evening seating. I might go with the higher quantity of nicheless lights on the house side because you have two main viewing areas. House side and right side / right side far corner. The nicheless will give much less glare.
 
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jimmythegreek

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You can put nicheless in any pool they screw into a return style fitting. Gets pricey but looks the best. With square pools you want to pay attention to spacing and equalness they flow better that way. You have to be careful if you plan to insulate. There are proper techniques none of which are easy. An auto cover excels and the ground is good insulation. You need 2" or more of ridgid foam to make a difference. Most insulated pools are concrete and are made from ICFs
 

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
You can put nicheless in any pool they screw into a return style fitting. Gets pricey but looks the best. With square pools you want to pay attention to spacing and equalness they flow better that way.
Wow I like this website - I wasn't aware of this new trend. Yeah it adds up but it might be worth it. The fact they screw in in a return is genius. I'll prepare a plan.

You have to be careful if you plan to insulate. There are proper techniques none of which are easy. An auto cover excels and the ground is good insulation.
Well here I respectfully disagree; earth temperature is about 13C or 56F in this area. If I target a water temperature of 30C or 86F, there is a pretty big differential.

But let me go in order and see if it makes sense. I would divide heat losses in:
  • evaporation
  • through the cover
  • through the walls into the dirt
Evaporation
I have been told that evaporation with an autocover pool in this area is about half an inch per month during swimming season. On a 18*36 ft pool that is almost exactly 200gal/month or 757 liters (and kg) of water. Water's heat of vaporization is 2260 kJ/kg that means 1.7GJ/month, 1.6M BTU/month or just about 53k BTU/day.

Cover
I read an assumption that the cover has an insulation value of R-1. 24-hour average temperature of air during the swimming season in this area should be around 60F (Yes it's never too warm, we do not have AC in the house). Target water temperature we said 86F. According to Wikipedia R-value is defined in US as (°F·ft2·h/BTU). This means losses will be (86-60)F * (36*18)sq ft * 24h / 1R = around 400000BTU/day

Walls
Let's be generous and give dirt a value of R-2. This is quite optimistic according several tables I have found, but the first 3-4 feet will have gravel, then there is some plaster between the dirt and the liner so let's use that value. This assumes good drainage, something I'll have to work on. After tedious analysis of the dig sheet, turns out the pool should have an internal surface of 1030sq ft. Using the formula above, with dirt temperature of 56F: (86-56)F * 1030sq ft * 24h / 2R = 370000BTU/day, almost as much as through the cover, (but probably more). Assuming one could put some sort of foam that has an R-10 the number becomes 74k BTU/day.

To put things in perspective, I need to consider the heat budget by estimating the contribution from the solar panels. I have not done this part of the analysis yet but I read a panel can deliver up to 40000BTU/day, so by insulating the pool it's like I have 7 more panels on my roof.

You need 2" or more of ridgid foam to make a difference. Most insulated pools are concrete and are made from ICFs
Yeah I was thinking about 4" of insulation but 2" might be enough.

I welcome feedback on my numbers.
 

jimmythegreek

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The ground is actually a decent insulator. The warmer water convects into the damp soil and warms it providing a break from the 50s average ground temps. Rigid foam helps break that thermally and it does work. The foam has to be thinner than the top lip of the panel so 4" would probably be max.
Planning a pool to be constantly heated is different. The main battle is pool volume. You want the smallest shallowest pool you can live with. Then the choice is what are you heating with. Solar excels for maintaining temps and some ideal weather heat ups but you cant count on it. For sporadic usage a gas heater shines. For constant temp a heat pump works well. Theres lots of variables and cost involved. Its a pay now or pay later situation.
 

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
The foam has to be thinner than the top lip of the panel so 4" would probably be max.
Thank you very much for your comments. The line above is very important but I am not quite sure I understand it. Maybe we are thinking of different ways to insulate.


Planning a pool to be constantly heated is different. The main battle is pool volume. You want the smallest shallowest pool you can live with.
Yeah you are right, pool size is a compromise. I could have a much bigger pool than 18x36 but I believe this is the size that will work best in my scenario. I hope the fastlane will "make it bigger" especially for swimming. I also want a deep end so the kids can jump into it and exercise to collect objects from the bottom, practice activities etc.

Then the choice is what are you heating with. Solar excels for maintaining temps and some ideal weather heat ups but you cant count on it.
Solar is definitely something we want to install - next year however, after we re-do the roof. This year it will have to work without external heating. I do not plan to buy a gas or heat pump heater right away; I'll make sure to put the plumbing together in a way that allows me to do it later on if we realize we want to do it.
However I believe insulation will make any such solution work better, and I consider it good practice. Thank you for the advice.
 

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
Auto-cover placement - I always assumed the deep side of the pool is the best location for the autocover location, but I wouldn't really be able to say why. Are there specific reasons I should choose one side or the other? I do not want to limit people from jumping into the pool for example. I believe the pool is dangerous if the autocover is not fully open, but which side is safer to open first?

I am almost settled with poolwarehouse.com as the pool wall, auto cover and vinyl liner provider. Unless there are other suggestions I should consider...
 

jimmythegreek

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Morris Cnty NJ
If you want a warm pool you need to heat it somehow. The auto cover and insulation isnt enough. I know its money but its best to do it all in one shot. Even if you dont run the gas line or electric it's easierto install it now.
When I said insulation thickness I mean keeping it under and inside of the wall lip. Unless you have seen the backside of a pool wall you wouldnt follow me.
 
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manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
You do not want much walking on the auto cover lid so that says nope to the shallow end! Jumping can happen from the sides!
OK! I'll stick with my original plan.


If you want a warm pool you need to heat it somehow. The auto cover and insulation isnt enough. I know its money but its best to do it all in one shot. Even if you dont run the gas line or electric it's easierto install it now.
Oh that's very good advice. I'm already runninng 230VAC for the fastlane, I'll make sure the wiring will also be able to support a heat pump. I can place PE gas pipe and a riser.
 

manoweb

Well-known member
Apr 14, 2017
130
Hayward CA
I did some basic research on the prevailing winds - turns out West is the main direction. I put the skimmers on the North East and South East sides. I'll have to check if those returns on the South West side are going to be compatible with the auto cover:

1585641771175.png
 

Baumeister

Bronze Supporter
Jul 11, 2018
13
Auburn,CA
I believe my wife wants a medium-darker liner so I shouldn't skimp on lighting power.
Manoweb, check with your local permitting authority on allowable liner colors. 2016(latest) California Building Code for swimming pools only allow white liners/pool shell color.

"3108B.3(formerly 3106B.3) Pool Construction
3106B.3 Finish Color. The finish color shall be white, except for:
(1) lane and other required pool markings described in Section 3109B
(2) handholds,
(3) copings,
(4) the top surface edges of benches, and
(5) the edge of spa steps.
Exception: A spa pool shall be permitted to be finished in a light (pastel) color other than white when approved by the enforcing agency.


The only darker-colored shells/liners I've encountered in California are on Indian land.
 

RoyR

Bronze Supporter
Jul 31, 2018
319
Escondido/CA
Need more returns to ”direct” floating stuff towards the skimmers....this will be helped along by the surface winds. If you keep the pool on the shallow end, you don’t need to heat it...mine is 84 today.