Pool Cooling Strategies with Tracking - Fountain, Evening, etc.

mas985 · Jun 16, 2020

Heat loss in a pool is more tightly correlated to dew point temperatures rather than air temperature. This is because both evaporation and sky radiation are dependent on dew point temperatures and those two are the top two heat loss components.

DB-Cooper · Jun 16, 2020

mas985 said:
Heat loss in a pool is more tightly correlated to dew point temperatures rather than air temperature. This is because both evaporation and sky radiation are dependent on dew point temperatures and those two are the top two heat loss components.

Yes, that is supported by this testing. Additionally, my pool often gets a nice breeze across it, but last night was particularly void of wind, so I think I had multiple things contributing:

1. Lower starting pool temperature (difference between ambient air temp and water temp was only a few degrees to at most 8-9 degrees for majority of the night)
2. High humidity lowered fountain's effect/evaporation
3. No wind/breeze to move cooler air over water

Future evenings overnights are dipping again to low 70s from the higher 70s giving me another 5 degree of air difference. The good news in all of this is since early last week's 100F weather subsided, I've not seen water temps over 86F despite mid 90s highs. 86 is a perfectly cool temperature for us. That said, despite it not being too hot right now (a little humid), I'm already at 86F water temp, so I may hit 87F today which would be consistent with the fact I had a higher starting water temp today. Humidity forecast for the next week is 45-50%, I wish I grabbed a measurement yesterday, but I suspect in the evening and overnight it was 60+% since we had a bit of a storm roll through.

DB-Cooper · Jun 17, 2020

Update: Hit 87F water temp yesterday, ran the system overnight, got it down to 83:

Log:
06/17 (Previous Day's Air Temps: 94 high, 72 overnight low), Fountain 8pm-730am (Low Speed) = Water Temp Differential: 87->83 = 4 degree differential
06/16 (Previous Day's Air Temps: 94 high, 76 overnight low), Fountain 8pm-730am (Low Speed) = Water Temp Differential: 86->83 = 3 degree differential
06/15 (Previous Day's Air Temps: 94 high, 69 overnight low), Didn't measure due to skunk incident
06/14 (Previous Day's Air Temps: 94 high, 67 overnight low), Daytime pump run, no fountain = Water Temp Differential: 86->81 = 5 degree differential
06/13 (Previous Day's Air Temps: 93 high, 68 overnight low), Fountain 8pm-730am (Low Speed) = Water Temp Differential: 86->81 = 5 degree differential
06/12 (Previous Day's Air Temps: 95 high, 64 overnight low), Daytime pump run, no fountain = Water Temp Differential: 86->81 = 5 degree differential
06/11 (Previous Day's Air Temps: 93 high, 63 overnight low), Fountain 1230am-730am = Water Temp Differential: 86->81 = 5 degree differential
06/10 (Previous Day's Air Temps: 100 high, 69 overnight low), Fountain 1230am-730am = Water Temp Differential: 91->84 = 7 degree differential
06/09 (Previous Day's Air Temps: 100 high, 77 overnight low), Fountain 1230am-730am = Water Temp Differential: 90->86 = 4 degree differential
06/08 ( Previous Day's Air Temps: 95 high, 74 overnight low), Fountain 1230am-730am = Water Temp Differential: 90->86 = 4 degree differential
06/07 (Previous Day's Air Temps: 95 high, 74 overnight low), Daytime pump run, no fountain = Water Temp Differential: 89->86 = 3 degree differential

mguzzy · Jun 17, 2020

Ah Heat transfer! I get nightmares when I think of it.

JamesR said:
Cracks me up that you folks think 86 degrees water temp is cool. . Mine hit 84 yesterday and we call that warm!! I went in the ocean last week on the jersey shore with my grandson and it was 62 degrees. Now THAT is cold.
.....still admiring the pool build you have there. That was one heck of a creative project!!! I would have looked at that sloping back yard and said: “ Nope, sorry honey no pool in this yard”. You really pulled it off.

I would love it if my pool was 84 naturally! If you want to cool your pool block the source that is irradiating it, that darn sun. Plant some trees! My pool sits amoungst a grove of tall trees on three sides. It gets direct sunlight maybe 3 or 4 hours a day. Even when the ambient temp is in the 100's and my neighbor's full sun pool is in the 90's, mine stays in the mid 70's. I had to heat my pool up from 68 to 80 on Saturday for guests and it has been cooling an average of 2 degrees a day since then, mostly from radiative cooling at night. The last time my pool hit 84 on its own without me firing up the heater, we had a heat wave of 110 degree days for a week.

RMcGirr83 · Jun 17, 2020

DB-Cooper said:
Update: Hit 87F water temp yesterday, ran the system overnight, got it down to 83:

I would suggest you use the table bbcode found on here. Maybe easier to read (haven't tried it myself).

mas985 · Jun 17, 2020

If you copy and paste directly from Excel or Google Sheets, the table will be automatically created. Like this:

Model	Manufacture	NHP	SVF	RPM	GPMb	GPMa	GPMc	WATTb	WATTa	WATTc	EFb	EFa	EFc
Energy Advantage Variable EAPVS2	Advanced	3.00	1.20	3450	40	67	88	1813	2114	2355	1.00	2.00	2.00
Quiet Flo Variable QFVS2	Advanced	3.00	1.20	3450	40	66	89	1887	2177	2395	1.00	2.00	2.00
Advantage Spa 34822SWN	Advantage	3.00	1.00	3450	37	63	88	1546	1891	2151	1.00	2.00	2.00
Advantage Spa 4.54822SWN	Advantage	4.00	1.00	3450	36	61	85	1674	1917	2163	1.00	2.00	2.00
Energy Advantage EAPUS22	Advantage	2.00	1.30	3450	41	68	90	1806	2102	2293	1.00	2.00	2.00
Energy Advantage Variable EAPVS2	Advantage	3.00	1.20	3450	40	67	88	1813	2114	2355	1.00	2.00	2.00
Evolution Pond ESBBVS2	Advantage	3.00	1.20	3450	34	58	80	2739	2797	2855	1.00	1.00	2.00
Quiet Flo Plus QFPUS22	Advantage	2.00	1.30	3450	35	59	82	1691	1844	2005	1.00	2.00	2.00
Quiet Flo Plus Variable QFPVS2	Advantage	3.00	1.20	3450	40	66	90	2095	2310	2580	1.00	2.00	2.00
Quiet Flo QFUS22	Advantage	2.00	1.30	3450	39	65	85	1708	1968	2139	1.00	2.00	2.00
Quiet Flo Variable QFVS2	Advantage	3.00	1.20	3450	40	66	89	1887	2177	2395	1.00	2.00	2.00
AGVS165 59927-XXXX	Aquaguard	1.70	1.00	3450	39	64	84	1255	1552	1572	2.00	2.00	3.00

DB-Cooper · Jun 18, 2020

Let's try:

Date:	Air Temp High	Air Temp Low	Air Temp Diff	Pumps	Fountains	Water Temp Start	Water Temp End	Water Temp Differential
06/18/20	94	72	22	Night	Yes	87	83	4
06/17/20	94	72	22	Night	Yes	87	83	4
06/16/20	94	76	18	Night	Yes	86	83	3
06/15/20	94	69	25	Night	Yes	N/A	N/A	N/A
06/14/20	94	67	27	Day	Yes	86	81	5
06/13/20	93	68	25	Night	Yes	86	81	5
06/12/20	95	64	31	Day	Yes	86	81	5
06/11/20	93	63	30	Night	Yes	86	81	5
06/10/20	100	69	31	Night	Yes	91	84	7
06/09/20	100	77	23	Night	Yes	90	86	4
06/08/20	95	74	21	Night	Yes	90	86	4
06/07/20	95	74	21	Day	No	89	86	3

mguzzy · Jun 18, 2020

If you could bottle up the BTUs you are trying to get out of your pool, put it in a package and send it to me for my pool.. I'll pay for shipping.

DB-Cooper · Jun 18, 2020

mguzzy said:
If you could bottle up the BTUs you are trying to get out of your pool, put it in a package and send it to me for my pool.. I'll pay for shipping.

Haha, it's so strange how much goes into this. Regardless, at 86-87 it can actually be chilly once the sun goes down. Another issue, my wife and son where rashguards most days for the SPF protection since we're out there so much. I started wearing one this week to cut back on the sunblock, but wearing one of those has a MASSIVE cooling effect. Once out of the water, you get outright cold instantly as the water is stuck to your body and cools down quickly in any breeze. I got so cold last evening I had to take it off, so that's possibly another reason my wife and I are preferring different temps.

JJ_Tex · Jun 18, 2020

DB-Cooper said:
Haha, it's so strange how much goes into this. Regardless, at 86-87 it can actually be chilly once the sun goes down.

Funny, thats been the biggest shock for us owning a pool is how narrow of a temperature window we tolerate, and that the window changes with the air temps.

Last night the water temp was 86 degrees and we all were weenies and jumped out of the pool and into the hot tub after a few minutes. This morning when I checked the pool, it was 83 but felt great because it was warmer than the air. Now both kids are in and loving the 86 degree water in the afternoon sun.

DB-Cooper · Jun 18, 2020

JJ_Tex said:
Funny, thats been the biggest shock for us owning a pool is how narrow of a temperature window we tolerate, and that the window changes with the air temps.

Last night the water temp was 86 degrees and we all were weenies and jumped out of the pool and into the hot tub after a few minutes. This morning when I checked the pool, it was 83 but felt great because it was warmer than the air. Now both kids are in and loving the 86 degree water in the afternoon sun.

Yes, this is an incredible point. The air to water differential has more to do with it than anything. When the air becomes cooler than the water, it feels great when in the pool but you get cold VERY quick when out of the pool (if you don't dry off).

Considering the average mid/late Summer Austin day is 97-100F, I'd say 88-89 is a perfect temp!

DB-Cooper · Jun 19, 2020

Only hit 86 yesterday despite warm and humid weather. Our overnight low wasn't great last night, it'll go down to low/mid 70s again and weather will be lower 90s for the next week, so I imagine I'll be able to hold at 86'ish.

Date:	Air Temp High	Air Temp Low	Air Temp Diff	Pumps	Fountains	Water Temp Start	Water Temp End	Water Temp Differential
06/19/20	95	77	18	Night	Yes	87	83	4
06/18/20	94	72	22	Night	Yes	86	83	3
06/17/20	94	72	22	Night	Yes	87	83	4
06/16/20	94	76	18	Night	Yes	86	83	3
06/15/20	94	69	25	Night	Yes	N/A	N/A	N/A
06/14/20	94	67	27	Day	Yes	86	81	5
06/13/20	93	68	25	Night	Yes	86	81	5
06/12/20	95	64	31	Day	Yes	86	81	5
06/11/20	93	63	30	Night	Yes	86	81	5
06/10/20	100	69	31	Night	Yes	91	84	7
06/09/20	100	77	23	Night	Yes	90	86	4
06/08/20	95	74	21	Night	Yes	90	86	4
06/07/20	95	74	21	Day	No	89	86	3

DB-Cooper · Jun 25, 2020

Update: I'll be doing less frequent updates, but I'm still logging. We had some real good rain and it only hit 82 yesterday. Now the pool is getting too cold, so I'm turning off the fountain and not doing night running. It'll be 91-92 today and some clouds but quite a bit of sun. Humidity is high, water temp is already back to 84.

Date:	Air Temp High	Air Temp Low	Air Temp Diff	Pumps	Fountains	Water Temp Start	Water Temp End	Water Temp Differential	Other
06/25/20	82	72	10	Day	No	83	81	2	Some rain and high humidity
06/24/20	92	73	19	Night	Yes	86	82	4
06/23/20	92	71	21	Night	Yes	87	83	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 71
06/22/20	96	78	18	Night	Yes	88	84	4
06/21/20	94	77	17	Night	Yes	87	84	3
06/20/20	94	70	24	Night	Yes	86	82	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 70
06/19/20	95	77	18	Night	Yes	87	83	4
06/18/20	94	72	22	Night	Yes	86	83	3
06/17/20	94	72	22	Night	Yes	87	83	4
06/16/20	94	76	18	Night	Yes	86	83	3
06/15/20	94	69	25	Night	Yes	N/A	N/A	N/A
06/14/20	94	67	27	Day	Yes	86	81	5
06/13/20	93	68	25	Night	Yes	86	81	5
06/12/20	95	64	31	Day	Yes	86	81	5
06/11/20	93	63	30	Night	Yes	86	81	5
06/10/20	100	69	31	Night	Yes	91	84	7
06/09/20	100	77	23	Night	Yes	90	86	4
06/08/20	95	74	21	Night	Yes	90	86	4
06/07/20	95	74	21	Day	No	89	86	3

DB-Cooper · Jul 4, 2020

The triple digits have reappeared and we hit 89 again. Admittedly, the pool was too cool for us until about July 2nd so I slowed my cooling efforts down. Yesterday was perfect, hit 88 and then briefly 89. I did switch to overnight cooling although humidity is crazy high right now in the evenings so probably a minimal effect. I did upgrade my fountain by reducing the size of other returns. Chart below.

Here's the upgraded fountain at reasonable pump speed, I can get it to go basically all the way across the pool at max speed or by reducing the other returns even more:

Date:	Air Temp High	Air Temp Low	Air Temp Diff	Pumps	Fountains	Water Temp Start	Water Temp End	Water Temp Differential	Other
07/04/20	99	74	25	Night	Yes	89	85	4
07/03/20	96	77	19	Day	No	88	84	4
07/02/20	94	79	15	Day	No	86	83	3
07/01/20	92	79	13	Day	No	85	83	2
06/30/20	89	79	10	Day	No	85	82	3	High humididty
06/29/20	86	75	11	Day	No	86	82	4	Rained at 5pm previous night
06/28/20	93	79	14	Day	No	86	83	3	High humidity
06/27/20	86	76	10	Day	No	84	82	2	Some rain and high humidity
06/26/20	94	73	21	Day	No	85	83	2	Some rain and high humidity
06/25/20	82	72	10	Day	No	83	81	2	Some rain and high humidity
06/24/20	92	73	19	Night	Yes	86	82	4
06/23/20	92	71	21	Night	Yes	87	83	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 71
06/22/20	96	78	18	Night	Yes	88	84	4
06/21/20	94	77	17	Night	Yes	87	84	3
06/20/20	94	70	24	Night	Yes	86	82	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 70
06/19/20	95	77	18	Night	Yes	87	83	4
06/18/20	94	72	22	Night	Yes	86	83	3
06/17/20	94	72	22	Night	Yes	87	83	4
06/16/20	94	76	18	Night	Yes	86	83	3
06/15/20	94	69	25	Night	Yes	N/A	N/A	N/A
06/14/20	94	67	27	Day	Yes	86	81	5
06/13/20	93	68	25	Night	Yes	86	81	5
06/12/20	95	64	31	Day	Yes	86	81	5
06/11/20	93	63	30	Night	Yes	86	81	5
06/10/20	100	69	31	Night	Yes	91	84	7
06/09/20	100	77	23	Night	Yes	90	86	4
06/08/20	95	74	21	Night	Yes	90	86	4
06/07/20	95	74	21	Day	No	89	86	3

Texas Splash · Jul 4, 2020

Yes, it's hot today. Wow. Enjoy. :swim:

DB-Cooper · Jul 4, 2020

Texas Splash said:
Yes, it's hot today. Wow. Enjoy.

Given we didn’t have strong winds in the forecast, I put my umbrellas up in the morning. It’s still only 88 despite the heat. My wife said she felt a little chilly in the water, outside temp is 99F, all you can do is laugh.

Happy 4th!

DB-Cooper · Aug 1, 2020

Updated chart below. With a consistently hot month, it does seem I can keep this pool under control. Rainy days or evening cooldowns really help, but those are so infrequent and don't hold terribly too long. Today will be 100F, it'll be interesting to see how high it gets. With running the cooling at night, I can keep the pool at 88 or 89 which is perfect. If we have unusually warm days that go above 103, I can see 90 and at worst 91, but it seems my pool is an 88-89. I'll keep tracking through the end of Summer as August is our worst month, but we had a terrible July so I think it'll be more of the same. I do think night cooling and/or the fountain does get me about a 1 degree drop, but the biggest correlation to temperature is the overnight low temp.

Date:	Air Temp High	Air Temp Low	Air Temp Diff	Pumps	Fountains	Water Temp Start	Water Temp End	Water Temp Differential	Other
08/01/20	98	73	25	Night	Yes	86	83	3	Rained 2" at 4pm previous day, got very cool
07/31/20	98	80	18	Night	Yes	88	84	4
07/30/20	97	77	20	Night	Yes	88	84	4
07/29/20	101	75	26	Night	Yes	88	84	4	Rained at 5pm previous night
07/28/20	97	76	21	Night	Yes	88	85	3
07/27/20	95	77	18	Day	Yes	86	84	2	Ran Spa up to 95 with heater. Hit 95 at 5pm then rain storm came in and cooled to 77
07/26/20	93	77	16	Day	Yes	86	84	2	Ran Spa up to 95 with heater. Hit 93 at 5pm then rain storm came in and cooled to 77
07/25/20	99	79	20	Day	Yes	88	85	3	Ran Spa up to 92 with heater
07/24/20	100	82	18	Night	Yes	89	85	4
07/23/20	99	79	20	Night	Yes	89	85	4
07/22/20	94	79	15	Night	Yes	89	85	4	High humdity over night
07/21/20	98	77	21	Night	Yes	89	85	4
07/20/20	99	76	23	Night	Yes	89	86	3
07/19/20	97	76	21	Night	Yes	89	85	4
07/18/20	100	77	23	Night	Yes	90	86	4
07/17/20	100	79	21	Night	No	89	86	3	Forgot to put fountain up
07/16/20	101	76	25	Night	Yes	90	86	4
07/15/20	104	78	26	Night	Yes	90	86	4
07/14/20	108	77	31	Night	Yes	91	86	5
07/13/20	106	79	27	Night	Yes	91	87	4
07/12/20	102	79	23	Night	Yes	90	87	3
07/11/20	100	79	21	Night	Yes	90	87	3
07/10/20	100	79	21	Night	Yes	89	86	3
07/09/20	97	79	18	Night	Yes	88	84	4
07/08/20	99	79	20	Night	Yes	88	84	4	High temp went to 88 at 4pm and clouds
07/07/20	93	79	14	Night	Yes	88	84	4
07/06/20	100	78	22	Night	Yes	89	86	3	Drizzle overnight, high humidity
07/05/20	100	76	24	Night	Yes	88	85	3
07/04/20	99	74	25	Night	Yes	89	85	4	Put some umbrellas out during daytime
07/03/20	96	77	19	Day	No	88	84	4
07/02/20	94	79	15	Day	No	86	83	3
07/01/20	92	79	13	Day	No	85	83	2
06/30/20	89	79	10	Day	No	85	82	3	High humididty
06/29/20	86	75	11	Day	No	86	82	4	Rained at 5pm previous night
06/28/20	93	79	14	Day	No	86	83	3	High humidity
06/27/20	86	76	10	Day	No	84	82	2	Some rain and high humidity
06/26/20	94	73	21	Day	No	85	83	2	Some rain and high humidity
06/25/20	82	72	10	Day	No	83	81	2	Some rain and high humidity
06/24/20	92	73	19	Night	Yes	86	82	4
06/23/20	92	71	21	Night	Yes	87	83	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 71
06/22/20	96	78	18	Night	Yes	88	84	4
06/21/20	94	77	17	Night	Yes	87	84	3
06/20/20	94	70	24	Night	Yes	86	82	4	Overnight low of 77, but 1-2" of rain at 7am lowered to 70
06/19/20	95	77	18	Night	Yes	87	83	4
06/18/20	94	72	22	Night	Yes	86	83	3
06/17/20	94	72	22	Night	Yes	87	83	4
06/16/20	94	76	18	Night	Yes	86	83	3
06/15/20	94	69	25	Night	Yes	N/A	N/A	N/A
06/14/20	94	67	27	Day	Yes	86	81	5
06/13/20	93	68	25	Night	Yes	86	81	5
06/12/20	95	64	31	Day	Yes	86	81	5
06/11/20	93	63	30	Night	Yes	86	81	5
06/10/20	100	69	31	Night	Yes	91	84	7
06/09/20	100	77	23	Night	Yes	90	86	4
06/08/20	95	74	21	Night	Yes	90	86	4
06/07/20	95	74	21	Day	No	89	86	3

mguzzy · Aug 1, 2020

Man! I wish you could send me some therms! They way my pool is always shaded it stays cold! We just had a run of 4 days in the 100's and I just checked my pools temp this morning... 70!

Dirk · Aug 1, 2020

Sorry, skipped to here after I read you're not interested in solar panels, which is what I was going to suggest. Wouldn't panels for cooling and heating pay for itself in the amount of gas you pay for in the fringe seasons? Anywho...

Have you considered shade sails? I see you mentioned umbrellas, but you could cover most if not all of your pool with shade sails, they don't have to be dragged around and they are "wind proof." They look cool, too. They're relatively easy to take down (when you don't need them). The other benefit is that I really enjoy having a place to hide from the sun, even while in the pool. Shade sails could cover both some portion of your pool and some portion of your deck.

I'm not sure exactly what heats a pool, how much is air temp vs sun exposure. I see someone was talking about dew point. But keeping sun off your pool bottom certain should help.

DB-Cooper · Aug 1, 2020

Dirk said:
Sorry, skipped to here after I read you're not interested in solar panels, which is what I was going to suggest. Wouldn't panels for cooling and heating pay for itself in the amount of gas you pay for in the fringe seasons? Anywho...

Have you considered shade sails? I see you mentioned umbrellas, but you could cover most if not all of your pool with shade sails, they don't have to be dragged around and they are "wind proof." They look cool, too. They're relatively easy to take down (when you don't need them). The other benefit is that I really enjoy having a place to hide from the sun, even while in the pool. Shade sails could cover both some portion of your pool and some portion of your deck.

I'm not sure exactly what heats a pool, how much is air temp vs sun exposure. I see someone was talking about dew point. But keeping sun off your pool bottom certain should help.

First, our gas is ridiculously cheap here, I pay $0.29 per CCF, which is about 25% the price of gas in California. Also, while solar heating would be nice for early season startup and might help to cool the pool in the evening, I'm not sure it's a cure all. I'd rather save the money and just use it for gas and heat as needed. For cooling, I'd rather spend on a Glacier than solar, but given the pool temperatures I've been able to maintain/average, I don't think a Glacier is that worthwhile, but I'll make that determination at the end of September.

Shade sails is something I have considered multiple times. I do have a few challenges just with the topography. I actually bought a huge shade sail, and I have used it for parts of my deck, but it is a lot of work to put up and take down. Originally, while the pool was under construction, I considered trying to put a shade sail from my main deck and attach it somewhere on the other side of the pool, however, there's nothing to attach it to. I'd have to put a large and very tall pole on the corners of my pool, it would quite disruptive to the view line. I may give it another go, trying to tie into the metal railing round the fountain bowls, however, it's a multi-person job. Also, I underestimated the amount of time it takes to get everything ready to go into the pool, I'm trying to minimize more things. Regrettably, between just getting dressed and sun block, I've got a ton of steps before going into the pool: Remove patio furniture covers, remove outdoor tv cover, lower four coolaroo shades, tie shades into each other and into the mounting hardware, uncover and ratchet up three umbrellas that are taken out of storage. It's a 10 minute ordeal and similar ordeal to clean up at the end of the night, the shade sail would add quite a bit more.

Anyways, 88-89 is the perfect temp for us, and we're able to pretty closely maintain that, so I'm pleasantly pleased and surprised.

Cheers!

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Pool Cooling Strategies with Tracking - Fountain, Evening, etc.

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