Solar Covers...useless?

Billiam

Member
Oct 16, 2016
13
New Port Richey, FL
Hello all. My solar system has been awesome since you guys helped me design and install it. Works beautifully. My question today is about solar covers. I've noticed with mine that it doesn't seem to affect temperature one way or the other. I've put it on, taken it off...temps are the same either way. Did I buy a bad one? Here is what I bought:

https://www.amazon.com/gp/product/B003TQMCMQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1#customerReviews

With or without, over the last couple weeks the water is about 80 degrees in the morning. Warms up to 87 (our set point) with the solar system pretty easily but is 81 again the next morning....with or without the cover. Is there such a thing as a cover that will keep the heat in better or is most of the heat leaving through the ground anyway? If it doesn't help, I'm wondering why bother with it?
 

CJadamec

TFP Expert
Apr 29, 2016
2,390
Quaker Hill, CT
Covers don't keep heat in so much as stop evaporation. Cover or no you are going to loose heat thru convection. If your current atmospheric conditions don't support a lot of evaporation then you won't notice a big difference when you have a cover on.

Yes covers are worth it . There are times when they won't make a huge difference but those times are by far the exception rather than the rule.
 

MinerJason

Bronze Supporter
Jan 29, 2018
269
Tucson, AZ
Ours made a huge difference, but some of that may have something to do with the extremely low humidity here. That said, removing it and putting back on got pretty tedious after a while, and it started to disintegrate after only 1.5 seasons, so we have no plans to get another one.
 

borjis

LifeTime Supporter
Aug 19, 2014
3,032
Pacific NW
I'd bet climate and humidity are big factors.

I could understand the how and why of a cover not being as necessary in Florida.

Though ANY pool with full sun exposure would benefit from a non-clear cover
to avoid faster chlorine uv loss.

I absolutely have to have one, otherwise I do lose heat rapidly and evaporation/having to refill.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,018
Tucson, AZ
Is your solar or pump running at night by chance? It seems that your pool is losing a lot of heat over night through some means other than evaporation. A solar cover, even on partially covering the pool, should hold your heat loss to less than a few degrees (like 2-3F) overnight.
 

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,703
Sydney, NSW, Australia
I don't know your climate, but when I first started heating in the spring down here, the ground and concrete were cold and took weeks to warm up. This year I started a bit later and didn't lose so much overnight. I'm now starting heating around October 1st, which would be the same as April 1st over/up there.
 

BasicTek

Bronze Supporter
Oct 9, 2016
867
Lake Mary, FL
The last couple of weeks have been extremely warm in FL. In my case I have a screen so having the cover on during the day doesn't change much but overnight it cuts the loss from 7-8 degrees to 4-5. That has a cumulative effect over time. So I've maintained an 85-93 degree pool over the last 3 weeks with cover. If you aren't screened and get direct sunlight I bet lately that the cover would actually impead your pool from heating during the day. For the best results when in the 80's during the day you need only cover at night, but if you are happy with these temps then uncover away.

I'd also bet over the next couple of weeks you will really know the difference as the overnight lows will be dropping to the lower 50's and some in the 40's. On those nights for a test try with the cover for a few days and then try without (if you don't mind a cooler pool)
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,840
Pleasanton, CA
With or without, over the last couple weeks the water is about 80 degrees in the morning. Warms up to 87 (our set point) with the solar system pretty easily but is 81 again the next morning....with or without the cover
Exactly how are you measuring temperature in the morning? Is it a float thermometer? To get an accurate reading in the morning (and before night), you need to run the pump for a minimum of 30 min to mix up the water. Surface temperature is not indicative of heat loss throughout the entire pool.

Losing 6F overnight is typical without a cover. However, heat loss should be about half of that with the cover on.
 

Billiam

Member
Oct 16, 2016
13
New Port Richey, FL
Exactly how are you measuring temperature in the morning? Is it a float thermometer? To get an accurate reading in the morning (and before night), you need to run the pump for a minimum of 30 min to mix up the water. Surface temperature is not indicative of heat loss throughout the entire pool.

Losing 6F overnight is typical without a cover. However, heat loss should be about half of that with the cover on.
I'm using the history function in the Pentail Screenlogic App to track whether or not there are any changes. It tracks outside and pool temps. I'm wondering if the pool cover I have isn't as good as I thought when I bought it. Although it has good Amazon reviews, some of the reviews say it provided them with no thermal benefits.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,840
Pleasanton, CA
A sheet of plastic is enough to prevent evaporation and retain heat which is the majority of the heat savings for the cover. So it doesn't matter much what kind of cover you use. However, with any cover, you should not have 6F of heat loss overnight.

Are you running the pump overnight and are you sure the panels turned off during this time?
 

MinerJason

Bronze Supporter
Jan 29, 2018
269
Tucson, AZ
I'm using the history function in the Pentail Screenlogic App to track whether or not there are any changes. It tracks outside and pool temps. I'm wondering if the pool cover I have isn't as good as I thought when I bought it. Although it has good Amazon reviews, some of the reviews say it provided them with no thermal benefits.
I'm guessing the temp sensor the Screenlogic app is using is in the plumbing somewhere and not in the pool? This means it's only measuring an accurate temp when the pump is running. And also, as previously mentioned, to get an accurate temp you really need to run the pump for quite a while to mix the water up. Pools have a lot of temperature stratification when the water's not moving. If the pump has been off all night, a reading from a temp sensor in a pipe on the equipment pad might be closer to ambient air temps than the pool water temp. What is your pump run time schedule?
 

Billiam

Member
Oct 16, 2016
13
New Port Richey, FL
I'm guessing the temp sensor the Screenlogic app is using is in the plumbing somewhere and not in the pool? This means it's only measuring an accurate temp when the pump is running. And also, as previously mentioned, to get an accurate temp you really need to run the pump for quite a while to mix the water up. Pools have a lot of temperature stratification when the water's not moving. If the pump has been off all night, a reading from a temp sensor in a pipe on the equipment pad might be closer to ambient air temps than the pool water temp. What is your pump run time schedule?

Yes, the sensor is after the pump before solar. Pump comes on at low RPM at 10am, solar and cleaner Noon till 2pm, back to low RPM with solar option ramp up from 2-5pm. When the pump shut down at 5pm last night it was 88 in the pool, it's been running for 30 min today and is at 82. Cover has been on for a few days.