More Solar Cover Questions

[MrLeadFoot]

I've had my pool for 23 years and, for many of the years, I would cover the pool for heat. Believe it or not, in all this time I've only bought two covers, both of which I think have lasted between 5 and 7 years. Neither of them fell apart by separating at the seams nor did either of them disintegrate. The bubbles simply started gradually popping over time until they became holes, and when a few holes developed I tossed them. Both covers were the blue covers from Leslie's.

I just threw out the second one, and I want a replacement for two reasons this time, heating the water and slowing FC breakdown. Now, I know some people don't believe covers do much in the way of heating a pool, but with a cover on my pool for a few days, my temp can get to 88F. In fact, I have to turn my pump on to circulate the water when the cover is on or the top of the water gets super hot, to the point where it wouldn't be good for the cover to sit on the hot water.

I'd like to hear opinions from those who have had covers in regards to the questions below.

1) Do the clear covers really heat the water MORE than blue covers? The blue ones work really well in generating, not just trapping, heat, and I find it hard to believe a light colored one like clear can even get hot, let alone generate more heat than the blue one. If they really do, I'd like to hear from you.

2) I suspect blue would be better, but will blue or clear be better to slow FC breakdown?

3) I've come across posts on here, and reviews on shopping sites, that say these covers are "disposable" because they disintegrate in a year, but that's not been my experience at all! They seem to last a LONG time for me. Have the quality of covers gone down that badly since I bought my last one?

4) The first cover I got, I trimmed to fit the challenging shape of my pool, as seen below, perfectly. I split the cover at the narrowest point between shallow and deep, to make it easy to simply roll up and remove each piece, or just let them float rolled up. Leaving one end covered enabled the family to enjoy one end or the other without uncovering the whole pool, too, when applicable. The second cover was narrower and followed the curves out of the narrowest point of the pool just enough so the cover could be held in place by the shape of the pool, but more of water in the round parts of the pool were exposed, especially in the shallow end. I don't think it mattered as far as heating is concerned, but will more exposure defeat the purpose of using the cover to slow FC breakdown? The narrowest part of my pool is about 14.5' and the length is 34, so I could get 34x16, and keep the curves in the deep and shallow ends exposed. If I want to cover all of the curves, though, I'd need at least 20' wide, and the cutting could become tedious if I really do have to replace these newer covers every year. What are your thoughts here?

 

[Griswald]

Covers do not "heat" the water. The sun heats the water. Covers insulate the water from the air, so less heat is lost.

 

[PoolStored]

In real world usage, it is almost impossible to detect a difference in water temperature between the different colors/type of solar covers. Theoretically, clear should be best, but the difference seems to be rather small in practice. By far the largest effect is preventing evaporation (greatest heat loss) at night. That is an obvious effect.

Doesn't matter if you cut into pieces to make it manageable, will still work just fine.

 

[MrLeadFoot]

Covers do not "heat" the water. The sun heats the water. Covers insulate the water from the air, so less heat is lost.

Sorry, I guess my wording wasn't as clear as I thought. What i meant was the sun heats the cover, and that heat is transferred to the water. Then, the cover helps retain the heat.

 

[IceShadow]

Sorry, I guess my wording wasn't as clear as I thought. What i meant was the sun heats the cover, and that heat is transferred to the water. Then, the cover helps retain the heat.

My experience is that effect is minimal - but I’m in Wisconsin and you’re in California, so our experiences could be very different.

 

[MrLeadFoot]

In real world usage, it is almost impossible to detect a difference in water temperature between the different colors/type of solar covers. Theoretically, clear should be best, but the difference seems to be rather small in practice. By far the largest effect is preventing evaporation (greatest heat loss) at night. That is an obvious effect.

Thanks for that. What do you think about color I relation to mitigating breakdown of FC? Would blue be better in that regard, or clear?

Doesn't matter if you cut into pieces to make it manageable, will still work just fine.

What I was trying to ask was not about multiple pieces, but rather what if I don't cover the entire pool? For example, if I use more of a rectangle piece right down the middle, and left the rounded parts uncovered, will it still help prevent breakdown of FC?

 

[MrLeadFoot]

My experience is that effect is minimal - but I’m in Wisconsin and you’re in California, so our experiences could be very different.

HI, Ice. I'm not sure I understand what you're referring to here. Are you talking about your experience of the minimal effect of a cover helping to transfer heat to the water, or the minimal differences between a blue cover and a clear cover?

What about the effects on FC breakdown? Did you happen to notice any?

 

[mknauss]

Solar Covers - Further Reading

www.troublefreepool.com

 

[MrLeadFoot]

Solar Covers - Further Reading

www.troublefreepool.com

Marty, I read that article, and similar articles. While indeed helpful, interestingly, they don't mention the common blue translucent cover, but do refer to the "opaque" covers. The articles also are based on theory. While theory is great, in this particular instance, I'd like to hear what others have experienced in the real world. For example, these articles say that the sun will heat the water better without a cover, and a cover simply helps retain heat. On the contrary, I have found, without a doubt, that the common blue cover is much more effective at helping to increase the water temperature (not just retain it) than the sun alone without a cover. And, many people, via all sorts of sites and reviews of covers, have reported the same thing in regards to thermal transfer. Although my pool gets full sun for AT LEAST 8 hours a day, without a cover my pool is hard-pressed to hit the very low 80s, and we'd have to have a string of 100 degrees days for that to happen. With a cover on in those same conditions, my pool can easily get to near 90 degrees. My wife won't even get in unless it's 86, so I cover it to get it warm, then take it off in those conditions. In fact, it might even be able to get warmer, but I've never left the cover on to see when it gets that warm.

Also, there doesn't seem to be much documented on the effects covers have on FC breakdown (positive or negative). I would think it would be significant, but I unfortunately didn't pay much attention to this when I used my covers, because I used them primarily for heat. I now would like to know which color, if any, would help slow FC breakdown, as that will help me with my color selection between blue or clear. For that matter, would a higher temperature increase FC breakdown? I don't know that, either, so that's another factor I should probably consider.

I hope this makes sense.

 

[woodyp]

On 3rd cover here....all blue light weight ones. I can notice no discernable difference in actually heating the water with a cover on. Retaining heat due to temp drops and evaporation is what they're all about.

Other than that.... buy your favorite flavor of snake oil they come in regarding color, thickness or advertising claims. As long as you cover about 85% of water surface you're about as well off. Neither a half point of FC or a half point of temp difference is worth chasing.

 

[MrLeadFoot]

On 3rd cover here....all blue light weight ones. I can notice no discernable difference in actually heating the water with a cover on. Retaining heat due to temp drops and evaporation is what they're all about.

Other than that.... buy your favorite flavor of snake oil they come in regarding color, thickness or advertising claims. As long as you cover about 85% of water surface you're about as well off. Neither a half point of FC or a half point of temp difference is worth chasing.

Thanks for the reply. I appreciate it.

 

[jmastron]

without a cover my pool is hard-pressed to hit the very low 80s, and we'd have to have a string of 100 degrees days for that to happen. With a cover on in those same conditions, my pool can easily get to near 90 degrees. My wife won't even get in unless it's 86, so I cover it to get it warm, then take it off in those conditions. In fact, it might even be able to get warmer, but I've never left the cover on to see when it gets that warm.

Just to emphasize a point -- when you say "without a cover" do you mean at night also, and "with a cover on" it's on all night? In my experience, that's by far the biggest gain from a cover of any sort, especially in our climate. Check the water temp at the end and beginning of the day -- if my cover is off on one of our normal cool overnights, the water temp can drop 4-5 degrees, with it on overnight, it'll drop 2-3 instead (don't hold me to those numbers, but it is noticeable), and the daytime gains start from there. Over the course of a week or so, that indeed leads to about a 10 degree difference for me too.

Now, there probably is some difference in effect during the day -- having a cover on when it's windy or cloudy is probably better than off, and there might be slightly more or less gain on a calm sunny day too, depending on the cover color, cleanliness, angle of the sun, etc. But in my experience that's all overwhelmed by the nighttime difference. Now, FC loss occurs primarily during the day, so that is affected most by having the cover on/off during the day. I've only had blue covers, so can't comment on other colors -- I'd guess clear would be a bit less effective against FC loss, but no idea how measurable.

Also beware of false temperature readings -- I run my pool pump mostly in the morning, and I've gotten excited seeing a high temp late in the afternoon with the cover on, only to stick my hand in and realize it's just the top couple inches. I'll run the pump to mix and thermometer will show the actual temperature is a couple degrees cooler.

Honestly, if you've been happy with blue covers (as I have) I would continue with that color.

 

[mknauss]

I use a blue, cheap, 8 mil cover on our pool for the months of April, May, September, and October. The cover retains the heat. The overall water temperature of the pool rises much more with the pool cover off the pool during the daylight hours here in the desert where our Spring and Fall temperatures are in the 90's to 110's. Then once the sun starts to set, you must get that cover on the pool to trap the heat in the water, or it quickly evaporates water (humidity in single digits) and the pool water cools. Without the cover, the water temperature in the morning will be close to the low air temperature that morning.

The covers are quite cheap, less than $100. I use them for two years, and get a new one. Might last another year, but they begin to get soft(?) and tear easily when I pull them off.

I also see little improvement in FC loss with the cover on. Maybe some, but not what I would call noticeable.

 

[kul]

I’ve used a blue solar cover for the past few years. Some of the benefits I see:

1) Less evaporation. With the cover on I can go 10-12 days before topping off water. Without the cover 6-7 days.

2) Less FC usage. Without the cover I lose 4 (+/- 1). With the cover on I lose 1-2. I don’t have a SWG so this is a big plus for me.

3) my pool stays warmer for longer

My covers never last, but with all the above positives it doesn’t bother me to buy a new one when needed.

 

[IceShadow]

HI, Ice. I'm not sure I understand what you're referring to here. Are you talking about your experience of the minimal effect of a cover helping to transfer heat to the water, or the minimal differences between a blue cover and a clear cover?

What about the effects on FC breakdown? Did you happen to notice any?

Minimal effect of heat transfer to water. I use a dark blue solar cover. But mostly that’s to prevent evaporation when the pool is warmer than the air (most of the time).

It definitely slows FC breakdown. I go through less FC when it’s on than when it’s off.

 

[jamesey]

I use a blue, cheap, 8 mil cover on our pool

+1 to what @mknauss said

I made the mistake of buying a 12 mil because I thought it would last longer, but they don't. My cover is on all the time overnight and towards the end of my 2nd season it started to deteriorate. Also, depending on the width, the extra weight is a real pain when using a reel

Buy them with the expectation that you'll be replacing them frequently

 

[MrLeadFoot]

+1 to what @mknauss said

I made the mistake of buying a 12 mil because I thought it would last longer, but they don't. My cover is on all the time overnight and towards the end of my 2nd season it started to deteriorate. Also, depending on the width, the extra weight is a real pain when using a reel

Buy them with the expectation that you'll be replacing them frequently

Ahhh, therein lies the rub (no pun intended, as you read on). I think that reels actually put significantly more stress on covers. When reeling the cover onto the reel, you're actually pulling on a piece of plastic - its weight, drag in the water, and added weight of water on the cover all add to that stress - hence, stretching the plastic polymers, which undoubtedly stresses the material more and more each time it's reeled up. Not to mention pulling on it again to unroll it albeit there's likely less stretching going on due to it being drier and less heavy than when rolling it up. Then there's the rubbing of the cover upon itself, simply by virtue of it being snugly rolled up onto itself as the reel rotates. So, the cover gets stretched as it's being rolled up onto itself, then when the force is stopped when you stop reeling, it rubs a little more when tension on the material is relaxed. And, if any part of the cover rubs on the edge of the pool or any decking surface, that's chafing the plastic right there, too. And, if it doesn't layb perfectly flat as it goes around the reel, there's creasing and wrinkling going on which, again, contributes to degradation of plastic.

Sure, while these might sound like little issues, they easily add up, especially when they're done over and over, and the plastic is already subject to uv exposure, temp fluctuations and the errant chemicals here and there.

II do NOT use a reel, so in my case there is very little stress put on the material. I simply roll the cover upon itself in the water. There is absolutely no stretching, creasing crinkling, rubbing or scuffing of any of the cover during this process. Sometimes I just let the roll float in the water, other times I take it out. When I take it out, I simply pick it up straight up and carry it without dragging it to a spot under an upper deck where it sees no sun whatsoever. As I mentioned previously, I split my cover into two pieces, so it's pretty easy to take the two halves out if I really want a clear, open surface.

To be clear, I did Not purposely cone up with this strategy of managing my cover. It just happened. My setup is just not conducive to using a reel, both because of the odd shape of the pool, and because a reel is too bulky in my environment. Apparently, I ended up just being lucky, in a way, because my covers have easily lasted over 5 years.

I actually called Leslie's yesterday, trying to see if they have a record of my purchases so I know which covers I'd been buying, 8, 12,or 16 mil. Their system happened to be down at the time, but they said they only carry 12 mil blue with 5 yr warranty and 16 mil gray with 7 yr warranty. I could have sworn their was a 5 yr and 7 yr warranty option when I bought mine previously, and knowing me, I probably went with the 5 yr., which leads me to believe I got the 12 mil cover.

Bottom line is if everyone else is only getting 1 or 2 seasons on their covers, and I'm getting 5 or so, I should continue spending the extra cash on the 12 mil, because it's a real PITA to cut covers to fit the weird shape of my pool!

 

[MrLeadFoot]

Minimal effect of heat transfer to water. I use a dark blue solar cover. But mostly that’s to prevent evaporation when the pool is warmer than the air (most of the time).

It definitely slows FC breakdown. I go through less FC when it’s on than when it’s off.

I guess you're right, in that you have a very different experience than I do with a cover and heat transfer. I wonder if your cover being a darker color has anything to do with it, as the darker the color, the more opaque it would be. But, more than likely it's the difference in our locations.

Nice to hear FC loss is lower, though, for sure.

 

[MrLeadFoot]

Just to emphasize a point -- when you say "without a cover" do you mean at night also, and "with a cover on" it's on all night?

When it's on, it's on overnight, too. When it's off, it's off at night, too.

In my experience, that's by far the biggest gain from a cover of any sort, especially in our climate. Check the water temp at the end and beginning of the day -- if my cover is off on one of our normal cool overnights, the water temp can drop 4-5 degrees, with it on overnight, it'll drop 2-3 instead (don't hold me to those numbers, but it is noticeable), and the daytime gains start from there. Over the course of a week or so, that indeed leads to about a 10 degree difference for me too.

Now, there probably is some difference in effect during the day -- having a cover on when it's windy or cloudy is probably better than off, and there might be slightly more or less gain on a calm sunny day too, depending on the cover color, cleanliness, angle of the sun, etc. But in my experience that's all overwhelmed by the nighttime difference. Now, FC loss occurs primarily during the day, so that is affected most by having the cover on/off during the day. I've only had blue covers, so can't comment on other colors -- I'd guess clear would be a bit less effective against FC loss, but no idea how measurable.

Also beware of false temperature readings -- I run my pool pump mostly in the morning, and I've gotten excited seeing a high temp late in the afternoon with the cover on, only to stick my hand in and realize it's just the top couple inches. I'll run the pump to mix and thermometer will show the actual temperature is a couple degrees cooler.

I've actually measured morning and afternoons with cover on and cover off. Mine definitely heats up faster with the cover on. I run my pump when the cover is on to ensure I circulate the newly heated water throughout the water column.

Honestly, if you've been happy with blue covers (as I have) I would continue with that color.

I was hoping to find someone else who might already have been a Guinea pig in regards to heat and FC loss across both light blue and clear colors. If clear really does result in warmer temps and filters out the detrimental effect of sun on FC, it makes clear an attractive option. I actually doubt clear helps heat a pool better than light blue by allowing more light through, and also doubt that clear will block enough sun to mitigate FC loss. So, unless someone has already found positive results on both fronts here with a clear cover, I will likely continue to use light blue.

 

[PoolStored]

I was hoping to find someone else who might already have been a Guinea pig in regards to heat and FC loss across both light blue and clear colors. If clear really does result in warmer temps and filters out the detrimental effect of sun on FC, it makes clear an attractive option. I actually doubt clear helps heat a pool better than light blue by allowing more light through, and also doubt that clear will block enough sun to mitigate FC loss. So, unless someone has already found positive results on both fronts here with a clear cover, I will likely continue to use light blue.

I think, because of your interest, you should be the Guinea pig and report your findings. This is the way many of our processes and recommendations have been established. (I'm not joking).