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

[DB-Cooper]

I put a post in my build thread about this, but after more research and testing, I felt a separate thread on it would be worthwhile. Here's the original post:

Austin, TX - Above Ground Salt Water Pool in Canyon - Construction Started 09/30/19

Man, this is one of the prettiest pools I think I've ever seen. The knife edge and the view just make it spectacular! Love the transformation! Thanks for sharing! --Jeff Thanks, I appreciate that. It makes the lengthy build and investment made more palatable to hear that. If the picture...

www.troublefreepool.com

Here's a copy paste of it:

To my fellow warm weather peers, all my fears about this pool getting too hot are coming true. So that re-enforces my going deeper and larger as well as going with a lighter plaster and coping color (we had originally wanted a very dark blue color but walked it back after concern about heat). Also, some years ago we looked at a real nice house with a pool, we loved that it had this black bottom pool with gold pebble in it (PebbleTech), man that's a hard no in Texas.

Anyways, Friday, Saturday and Sunday, we've hit 89 degree pool water and hit 90 on Sunday evening. While I actually find 89 to be a comfortable temperature, any more than 90-91, and I might feel it too warm. This is during a heat wave for this time of year, but this is pretty seasonal weather in July and August in Austin. Hopefully it doesn't get too bad. We hit 88 in May as we saw a few real hot days, but then it went back down to low 80s. However, cooler weather really isn't in sight anymore.

I'll report on my attempts to combat this here.

06/05 - High of 95, Low of 72
06/06 - High of 95, Low of 74
06/07 - High of 95, Low of 74
Today 06/08 - High of 101, Low of 79
Tuesday, High of 104, Low of 69
Then back to mid 90s

On Friday and Saturday at 7am, pump startup, water was 85, it didn't take too long in the morning before we were at 86. It was 89 when we got in and stayed there for several hours despite peak of day heat. Pumps off at 730pm. On Sunday, startup was 86 and it heated to 89 quickly and finally hit 90 by end of the evening.

Yesterday (Sunday 06/07), I did just install this $25 Amazon fountain after reading about Speedy's here. I ran it for 6 hours last night combined with bowl fountains. Up until last night, I had not changed my pump scheduling which was basically running 8am-8pm.

I'll report daily progress in the next post.

Picture at a relatively low/medium pump speed (2200 rpm):

 

[DB-Cooper]

Last night, I ran my pumps at 40GPM for 6 hours, from 1230am - 630am. This included running through the new PVC fountain as well as my standing fountains. I had hoped for more progress than a 4 degree drop, but subsequent days without the fountain and running pumps during the day, we saw a 3 degree delta from 8pm to 8am.

Log:
06/08 (Yesterday 95 high, 74 overnight low), 1230am-730am = 90->86 = 4 degree differential

I'll run it again tonight, but today we're facing triple digit temps as we are tomorrow, however overnight lows are still in the low/mid 70s. Humidity isn't too bad, 30-40% during the days.

While I didn't expect miracles, I hoped for better. I get full sun all day as well. I'll post daily as I have read that it takes several days for the effects to really show.

Here's the fountain running in it glory, my previous post's photos was before I shut off some returns:

 

[see_feel]

Interested to see what happens over the next couple of days. Given your water volume, you may need another fountain to cool the pool more efficiently and to a lower temp.

 

[DB-Cooper]

Interested to see what happens over the next couple of days. Given your water volume, you may need another fountain to cool the pool more efficiently and to a lower temp.

I intended to buy another, but I also may need to cap some returns. I was hoping to see more progress with one than I have.

Water is already up to 88. My friend in Austin has a pool with more shade that’s consistently cooler than mine; he’s at 87 so I guess this is just normal. I’m ok as long as I can keep it around 90/91 in the worst days.

 

[JJ_Tex]

I kicked on our water features a second ago to try and help since we are 86, but expecting August like temps for tomorrow so it may not do any good.

The spa spillover return that is in the floor of the spa is threaded. I wonder if there is something similar for that return that I could rig up there as well.

 

[RMcGirr83]

lighter plaster

This is exactly what we went with. Pool today is at 88 but that's with a solar cover on it overnight. May just stow that come July or so.

 

[Texas Splash]

That's nice, and you can't beat that view. I have a simple PVC set-up to do the same. Water temp just crossed 94 degrees.

 

[mas985]

Is that an infinity edge pool? The water traveling down the sides should cool off very quickly at night. The rate of evaporation is directly proportional to the amount of water/air surface area. This is why fountains can reduce temperatures but even there, more area (i.e. water droplets) is advantageous.

However, if you want to cool the water without the higher evaporation, using solar panels at night is the most effective method.

 

[JamesR]

Pool cooling?? Man you folks down in the southwest have the opposite problem of us up here in the Northeast.
I am not familiar with cooling methods but to the OP, with the 28,000 gallon pool. That is the same volume as mine and I know the btu capacity it takes to heat it 1 degree, so you need the same sort of energy to cool it 1 degree as well. I cant see a fountain like that doing that much. If the principle is cooling by evaporation, then I would assume you would have to lose a bit of water to notice a significant temp change in that volume pool. I can see it increasing your pH though due to the aeration. But what the heck do I know.... Never tried to cool my pool water before!! If I told my wife I was cooling the pool, she would smack me.
BTW..... that is one heck of a nice pool!!! Wowser.

 

[DB-Cooper]

Is that an infinity edge pool? The water traveling down the sides should cool off very quickly at night. The rate of evaporation is directly proportional to the amount of water/air surface area. This is why fountains can reduce temperatures but even there, more area (i.e. water droplets) is advantageous.

However, if you want to cool the water without the higher evaporation, using solar panels at night is the most effective method.

It's a fake edge, basically it's a reverse knife edge that sits 3" below the waterline. If water goes over, there is no catch basin, that water is lost and runs down the hill. The cost and complications of an infinity weren't worth pursuing. Nobody is every back there so the visual appeal would be lost.

I don't have solar heating and don't think it's worthwhile to add. I'd rather use that cost on a Glacier if I had to as my 400K BTU heater can heat the pool exceptionally fast in spring/winter, so using it solely for cooling probably isn't the best spending of money.

 

[DB-Cooper]

Pool cooling?? Man you folks down in the southwest have the opposite problem of us up here in the Northeast.
I am not familiar with cooling methods but to the OP, with the 28,000 gallon pool. That is the same volume as mine and I know the btu capacity it takes to heat it 1 degree, so you need the same sort of energy to cool it 1 degree as well. I cant see a fountain like that doing that much. If the principle is cooling by evaporation, then I would assume you would have to lose a bit of water to notice a significant temp change in that volume pool. I can see it increasing your pH though due to the aeration. But what the heck do I know.... Never tried to cool my pool water before!! If I told my wife I was cooling the pool, she would smack me.
BTW..... that is one heck of a nice pool!!! Wowser.

pH hasn't noticably gone up, but I've always been fighting it (brand new pool, 45 days since plaster). I'm adding 15-20 oz of acid daily, today was no different despite how much swimming we did and all the fountains.

Agree on the cooling needs for a large pool. We get good wind, I was hoping with the wind and nothing to block it we'd get some more cooling than 3-4 degrees in the evening when air temps are low 70s. It's possible the fountain bought me an extra degree of cooling overnight. Both of my friends saw a 3 degree drop overnight, I saw a 4. My pool also stayed at 86 for a reasonable amount of time this morning, suggesting it wasn't like 86.9.

I'm at 89 now, and it's only 1pm. 95 air temp right now, heading to 99 by early evening. Will definitely hit 90 again, hoping we don't get 91. Thanks for all the help/commentary.

 

[DB-Cooper]

Hit 90 briefly, once the sun went down it went back to 89, so despite today’s warmer weather I basically matched yesterday’s results. Will run the fountain again overnight.

 

[RMcGirr83]

We hit 94 yesterday with the solar cover on. Solar cover is no longer on and has been stowed.

 

[DB-Cooper]

Update log below. Yesterday hit 100. With the fountain running, the prior day we say a 4 degree differential overnight. It only hit 90 in the evening time, so it held at 89 for majority of the afternoon. I expected to see 91 earlier in the day, but it didn't happen, showing some form of stability or maxing out even with the 100F day and direct sun. Today, we will hit 100 or possibly 102 so it'll be another metric to test. Last night's overnight lows at 77 were much higher than previous days. Tomorrow morning early AM overnight lows will get to 68F and tomorrow will have 94F weather, so we can test a 10 degree overnight air temp differential and hopefully see more progress. You can see the log below, but effectively the same result as before despite higher temperatures both in daytime and overnight, so I feel somewhat better:

Log:
06/07 (95 high, 74 overnight low), Daytime pump run, no fountain = 89->86 = 3 degree differential
06/08 (Yesterday 95 high, 74 overnight low), Fountain 1230am-730am = 90->86 = 4 degree differential
06/09 (Yesterday 100 high, 77 overnight low), Fountain 1230am-730am = 90->86 = 4 degree differential

 

[DB-Cooper]

That's nice, and you can't beat that view. I have a simple PVC set-up to do the same. Water temp just crossed 94 degrees.

Following what I think you posted in another thread, I bought a fan spray nozzle. I’ll need to add an inch or two of water this week, plan to use that propped on a chair. I’ll probably do it very early in the morning when it’s not crazy hot. It’ll be an interesting variable to see. Any best practices there?

 

[RMcGirr83]

I’ll need to add an inch or two of water this week, plan to use that propped on a chair.

You don't have an autofill?

 

[DB-Cooper]

You don't have an autofill?

Yes I do, but it's not hooked up the the main water supply as they're still working on the plumbing for my outdoor bathroom. The auto-fill is on the other side of my bathroom and feeds through the bathroom. The final plumbing permits aren't closed yet.

 

[DB-Cooper]

Just hit 91. Cooler weather rolls in tomorrow early morning. Hope it helps.

One hour later and back to 90. Swimming and running fountains. Ambient is still high so that’s a surprise.

An hour later, still 90. Sun is almost gone, my wife says it’s getting too cold. Air temp is still 93 with a very mild breeze. Maybe I’m fighting an unnecessary battle.

 

[Texas Splash]

Following what I think you posted in another thread, I bought a fan spray nozzle. I’ll need to add an inch or two of water this week, plan to use that propped on a chair. I’ll probably do it very early in the morning when it’s not crazy hot. It’ll be an interesting variable to see. Any best practices there?

Not really. We just prop it up and try to allow the sprayed water to grab some cooler air on the way down. Since it's a gentle fan hitting the water it doesn't really increase the pH. Our water temp was 96 yesterday. Hot & muggy. Ugh.

 

[Turbo1Ton]

An hour later, still 90. Sun is almost gone, my wife says it’s getting too cold. Air temp is still 93 with a very mild breeze. Maybe I’m fighting an unnecessary battle.

I thought the exact same thing last night. We had ridiculous winds yesterday. Air temps maxed out around 95, mid afternoon. Around 3 o'clock the winds came in and started bringing the temps down. By the time I got home to get in the pool about 6-6:30 pm, water temp was 91 degrees on my floaty thermometers, air temps were upper 80's (88 I believe at the time I got in the pool), the wind was averaging about 10-12 mph and gusting up to 20-25 mph. My son and I were in the pool for all of about 15-20 minutes before we decided it was too cold and we were going in. Drying off was miserable! We had to go find a corner of the house where the wind couldn't get to.

If someone had told me 91 degree water would feel cold, I would have called them a liar.

You are beating me to this whole thing. I planned on doing this exact experiment over the summer. I am just about a week or so behind you. So I am watching this intently to see what your results are. Although mine may differ since my pool is about half the volume of yours.

--Jeff