Liquid Solar Covers - Do they work?

newbiepool

LifeTime Supporter
Jul 30, 2011
52
Richmond VA
Liquid Solar Covers - Do they work? I have no wind issues, I do have 2 laminars and a 3 way waterfall. But they get turned off when no one is using the pool. I'm trying to see if I can get away from a bulky cover. I have read that it works great for still water, but doesn't the skimmer cause issues with this?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
I wouldn't say they work "great" since that implies they work as well as a bubble-type solar cover, which they don't. However, they can work well in environments with little wind and where the humidity isn't too high since what they mostly do is cut down evaporation. They may retain heat as well as a thin solid cover which retains heat about half as well as a bubble-type cover since both prevent evaporation but the latter also insulates so minimizes conduction/convection. When they work well, they roughly cut down heat loss in half whereas a bubble-type cover can cut it down by 75% or more.

The skimmer does not affect the operation of a liquid solar cover. If some of the chemical gets circulated, that's OK and it will rise up to the surface after coming out of a return. The chemical has a long hydrophobic end and is less dense than water. When on the surface of the water, the hydrophobic ends sticks out while the small hydrophillic end stays in the water and with enough product a thin single-molecule layer is formed that helps to prevent evaporation of the water.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
It is biodegradable (not sure why that matters, unless you are referring to backwashing) and should not have any issues with pool equipment since it's just a long-chain alcohol so isn't particularly reactive. The specific alcohol used in different products varies with some using cetyl alcohol, others using stearyl alcohol, and some using mixtures of these or other long-chained alcohols. Note that isopropyl alcohol in these products is just a carrier that evaporates. Some products also contain calcium hydroxide to help with dispersing the product evenly, but then the calcium hydroxide dissolves in the water.
 

newbiepool

LifeTime Supporter
Jul 30, 2011
52
Richmond VA
i bought one of them and cut the fin a little bit way too big... but it emptied itself within 48 hours. Water still clear, but i noticed my water stayed at 80 in the morning 2 nights running. the air temp has been falling to the mid 70s at night. I remembered the water temp at 77 the morning before I put it in... it must be working>

On thing that bugs me is the T Cell temp shows a different temp reading than the water temp sensor... which should I believe?
 

rsmile01

New member
Jun 6, 2011
1
I have a few questions about liquid covers. Let's assume we're using the alchohol-based stuff.

Does it add any color to the pool surface? Can it be seen any way?
Does it change the feel of the water in any way?
Does it run through a cartridge filter without causing any clogging issues?
Would it react with borates in any way?
Does it wear off over time? For a 16'x32' surface in-ground pool, how much would have to be used to keep it in check?

Thanks for your help!
 

Andrew Sarchus

Active member
Apr 11, 2011
31
Seattle
rsmile01 said:
I have a few questions about liquid covers. Let's assume we're using the alchohol-based stuff.

Does it add any color to the pool surface? Can it be seen any way?
Does it change the feel of the water in any way?
Does it run through a cartridge filter without causing any clogging issues?
Would it react with borates in any way?
Does it wear off over time? For a 16'x32' surface in-ground pool, how much would have to be used to keep it in check?

Thanks for your help!
I don't know about carts or borates, but I couldn't feel or see it. And the packages say to add more regularly.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
rsmile01,

Welcome to TFP! :wave:

It shouldn't add any color nor be seen except perhaps in its indirect effects on the surface tension of the water (i.e. might shimmer differently). It shouldn't change the feel of the water though technically you do pull some off onto your skin when you get out of the pool. It doesn't clog through any filter. It shouldn't react with borates or other chemicals. It doesn't wear off, but as noted, it does get removed over time with bather entry/exit and by attachment to some organics that might get filtered out.

Results are mixed. To get any benefit at all, you have to have fairly still air. If you have fairly constant wind (even a light breeze), it will tend to blow into one area of the pool and not work well. Even under ideal conditions, it works perhaps half as well as a real bubble-type solar cover since it reduces evaporation but does not significantly insulate.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Unlikely. Certainly not by physical filtration. The molecule is way too small for that. It might be adsorbed into filter media or already captured organic material that attracts other organic material. However, to get into the filter, it would have to get sucked into the skimmer via a vortex since it normally tends to stay on the surface of the water since it is not water-soluble and is less dense than water. Think of this as being similar to an oily film on the water that normally needs a scum ball to remove, though it is just a one molecule thick layer (if dosed correctly). Speaking of which, you wouldn't want to use a scum ball when using this product since that would likely remove it.
 

iflyjetzzz

Well-known member
Jun 16, 2011
79
Las Vegas, NV
Sounds interesting. I take it that using this in conjunction with a traditional solar blanket during the winter would help the pool water retain its heat a bit better.
 

cramar

TFP Expert
LifeTime Supporter
Nov 10, 2010
1,143
Sault Ontario
I read a lot on this topic over the summer and I found that opinions were generally split, some people say they are great and some say they lousy.
Since they are relatively cheap it's worth some experimentation if one is curious enough, if you can establish a rough baseline of temps under your "usual" process and then switch to liquid and see what happens. I found that most people said wind undermined the product and we have pretty consistent wind where I live.
 

iflyjetzzz

Well-known member
Jun 16, 2011
79
Las Vegas, NV
cramar said:
I read a lot on this topic over the summer and I found that opinions were generally split, some people say they are great and some say they are ****.
Since they are relatively cheap it's worth some experimentation if one is curious enough, if you can establish a rough baseline of temps under your "usual" process and then switch to liquid and see what happens. I found that most people said wind undermined the product and we have pretty consistent wind where I live.
... that's why I'm wondering how they would do in conjunction with the solar cover that I currently have. Since my 16 mil thick solar cover shields the water from wind, I am hypothesizing that it would help insulate the water from losing heat in the winter.
My solar cover is less than a year old and it's already pretty much trashed. I'll take it through this winter and next summer but next fall, I'll find out how good the 4/10 year warranty is on the cover. At that point, I'll probably experiment with a combination of the new cover and the trashed cover for next winter.
I used my pool quite a bit last winter and we have an attached spa that we used just about every day last winter. That heated water would go into the pool when the water was filtered, although we could have the spa water run in a somewhat closed loop when we were in the spa.
I got the pool cover last winter. Based on my observations, the pool temperature dropped 6 degrees/night with no cover and 2 degrees/night with a cover on the pool. Of course all of that is dependent on the pool vs air temperature differential.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
iflyjetzzz said:
... that's why I'm wondering how they would do in conjunction with the solar cover that I currently have. Since my 16 mil thick solar cover shields the water from wind, I am hypothesizing that it would help insulate the water from losing heat in the winter.
It won't help at all. The layer of chemical is ultra-thin so does nothing to prevent heat loss from conduction or radiation. It only prevents heat loss via evaporation, but a regular solar cover eliminates evaporation already so there is no benefit to adding the liquid solar cover product. If you want better insulation, then use a better solar cover that is thicker, especially in terms of larger bubbles (greater thickness from bubble end to top of cover). The insulation is provided by the still air trapped in the bubble and in between the bubbles. You could add an additional insulating foam cover on top of it, but it would need to be waterproof from rains (you don't get much rain where you live so might be OK).

It sounds like you didn't get a very good cover having it only last 1 year. The thicker covers last longer, but are more expensive. It's probably a wash except that you don't have to change the cover as frequently with the thicker covers that last perhaps 2 or 3 seasons instead of 1. The thickness here is the "mil" thickness of the plastic itself.

As for the effectiveness of good solar covers, they usually cut heat loss by around 75% so should have cut it from 6 degrees to 1.5 degrees. You saw 2 degrees which may indicate again an inferior (too thin) cover.
 

iflyjetzzz

Well-known member
Jun 16, 2011
79
Las Vegas, NV
chem geek said:
It won't help at all. The layer of chemical is ultra-thin so does nothing to prevent heat loss from conduction or radiation. It only prevents heat loss via evaporation, but a regular solar cover eliminates evaporation already so there is no benefit to adding the liquid solar cover product. If you want better insulation, then use a better solar cover that is thicker, especially in terms of larger bubbles (greater thickness from bubble end to top of cover). The insulation is provided by the still air trapped in the bubble and in between the bubbles. You could add an additional insulating foam cover on top of it, but it would need to be waterproof from rains (you don't get much rain where you live so might be OK).
Thanks much. I was half expecting that response (no value). I didn't know if the liquid could offer insulative properties.

chem geek said:
It sounds like you didn't get a very good cover having it only last 1 year. The thicker covers last longer, but are more expensive. It's probably a wash except that you don't have to change the cover as frequently with the thicker covers that last perhaps 2 or 3 seasons instead of 1. The thickness here is the "mil" thickness of the plastic itself.
Fortunately, it carries a 4/10 year warranty. I'm a renter and our current lease expires Oct 2013; we will definitely move from Tucson summer 2014 so I'm not looking for something that will last longer than 2014.
Both of my neighbors across the street opted for solar heating units. Not an option for me, as that's a lot more expensive than a simple cover.

chem geek said:
As for the effectiveness of good solar covers, they usually cut heat loss by around 75% so should have cut it from 6 degrees to 1.5 degrees. You saw 2 degrees which may indicate again an inferior (too thin) cover.
That was a ballpark estimate from my observations. I didn't watch it all that closely but 75% may be what I was able to get. Even if it was 67%, that still made my pool completely usable last winter with only a bit of daily heating.
I assume that since I've lost ~1/3 of my bubbles, the cover won't do as good a job of retaining heat this next winter. Is that correct? If so, I think I'll exercise my warranty and get a new cover for this winter and will likely use both covers together. I think that I'd be able to roll both of them up and remove them without much additional effort. Do you see that as a viable way to add additional insulation?
If I do that, I'd put away the good (new) cover next summer and just use the old one next summer, as I don't need as much insulation during the summer ... I need a bit of insulation to keep the pool warm in the summer but not as much as during the winter.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Yes, with 1/3rd of the bubbles gone it won't insulate as well. You should get it replaced under warranty. Also, note that when you roll up the cover you should cover it with a light or reflective cover/tarp or put it in a covered box. If you leave it rolled up and in the sun, then the heat and UV from the sun will degrade the cover. When the cover is on the water, this excess heat is conducted to the water, but when the cover is rolled up it just heats the cover to excessively hot temperatures and degrades it.
 

GreatCanadian

LifeTime Supporter
Jul 28, 2011
844
St. John's, Newfoundland
Been reading this with interest, and I don't think it's necessary for me to start another thread. Don't want to hijack this one either so I will gamble and ask this one quick question here. Solar covers - bubbles up or bubbles down? Thanks.
GC
 

Vandergraff

Well-known member
Jun 22, 2010
84
I posted this question on a thread in Chemistry 201 anyone-ever-use-this-cover-free-product-before-t33711.html

But no response.

So I will try here as well.

-----------------
So I get 'the kind of sort of' - but here is the thing.

This year I added ~1.5 oz Heatsavr each day (I am doing BBB method so no big deal to add Heatsavr at the same time) and the pool was getting 85 - 87F at the end of the day. Pool heating is by 7 SunEarth Solar panels and we are in the Santa Cruz Mountains near the Bay area in CA. This summer has been much cooler than average here - and at 1700' elevation (night temperatures drop into the 50s sometimes 40s) - this seems pretty good.

I ran out out of Heatsavr 4 days ago. Since then we have had mini heatwave (day time 90s night 60s) - but the pool is only getting to 83F at the end of the day.

The family prefers the 85F+ and wants me to get some more of the Heatsavr.

At the end of the season I don't really want order online and my local pool store has switched from Heatsavr to COVERfree. Anybody used both? I am somewhat (more) skeptical of COVERfree as it says it only needs to be added once a week rather than daily for Heatsavr.

I should probably add that our pool is maybe the best location for these kind of products - very sheltered (fence, trees and terrain) so a suntrap but with almost no wind.