Liquid Solar Pool Cover

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
I disagree. IF you have little wind so that the surface of the water doesn't get chopped up, then coating the surface with a single molecule layer of a long-chained hydrocarbon alcohol, which is what these products are, will help reduce evaporation and therefore help prevent heat loss from evaporation (they do not "insulate" thermally -- they just reduce evaporation rates and evaporation is the leading cause of net heat loss, especially at night). They obviously don't work as well as a solar cover, but they do work -- again IF there is no wind.

SolarPill works via the exact same concept as Ecosavr. The specific chemical might be different and may lead to different effectiveness, but the principle is the same for both.

That said, I have not used either so cannot vouch for either. I'm just giving my 2 cents with regard to its theoretical usefulness and I've heard pool users in my local pool store say that the solar fish products (which are also similar) did help retain heat in their pools, but not by a lot and only on calm days.



TFP Expert
Apr 15, 2007
Ft Lauderdale, Florida
I'm with ChemGeek...but I'm slightly biased on this as I always highly recommend using some sort of cover for your pool (we manufacturer heat pumps too).

These chemical blankets are not good for heavy windy conditions (as ChemGeek said), but also if you have a vanishing edge or negative edge pool, constantly used waterfalls, or lots of fountains. The chemicals will tend to skim off the top and end up in the trough of a vanishing/negative edge pool, and windy conditions or aggitation will continue to break the surface tension of the chemicals, allowing the heat to escape.
I've done presentations in which you can take a hot steaming cup of water, add a drop or two of the heatsaver and you can literally see the escaping steam close up.

There are proper applications (flat water without alot of water features or wind), and there are applications in which it will not work.


TFP Expert
LifeTime Supporter
May 30, 2007
South Carolina
Thanks very much for your opinions.

It does appear, based on Richard's & Sean's comments, that we actually DO HAVE a pool that fits the criteria of a good probability for this to work! Thank you both for taking the time to state your theories and list the necessary information for us to make a decision to at least try it!

Next spring, we may be in the water early! :-D


Dec 8, 2007
I tried it a few years ago and did not notice any noticable difference.

I bought several with the "return back" money guarantee. I tried returning it (Leslie Pool Supply) and was never able to. They always found a reason NOT to give me my money back on the un-used fishies. :cry:


New member
Jun 3, 2011
These have to be a waste of time and money. First, they will be skimmed off the top of the pool the first time the filter runs. Secondly, the main loss of heat is not from evaporation, but from radiation of heat from the pool water to the air. As haze said, it's THERMODYNAMICS. If this product really worked, then imagine how well a single pane glass window would work to keep heat in your house. Don't waste your money.


Well-known member
Aug 1, 2010
dadwright said:
Secondly, the main loss of heat is not from evaporation, but from radiation of heat from the pool water to the air.
I've always been told it's evaporation. I can see the steam rising off my pool in our cool still nights.


TFP Expert
Sep 21, 2009
Greentown, IN
My biggest concern is what they are adding to the pool. Will it gum up the filter, put a line of film on my liner, is it safe for swimmers?

Also.. does the filter just remove it right away?

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
dadwright said:
they will be skimmed off the top of the pool the first time the filter runs.
If your pump is running so strong that it creates a vortex, then you would be right, but usually the water flow isn't that high so the product remains on the surface. Also, any product going through the filtration system will end up going right through any filter and back into the pool. The molecule is far too small to get caught in any filter. It might get caught by some types of clarifiers, though even that may not happen since the molecule is uncharged (though the alcohol end is polar).


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
This study also confirms that without a cover, evaporation is the largest component of heat loss. But you can also use some of the formulas presented in the paper to prove it to yourself.


Well-known member
May 26, 2011
I have been using a similar product for the past week and have noticed some retention of heat at night. Not as good as a solar blanket but better than nothing. For the cost of it I say its worth a try.


New member
Mar 5, 2011
I know this is an old post but.....

Has anyone tried using Isopropanol as a liquid cover? Looking at the safety datasheet heatsavr is 95% IPA.



TFP Expert
May 20, 2007
South Central NJ
First, I know a couple of people at the place that makes the fish you through in your pool or use via injection. Second, the stuff works if the pool is still. Disturb the water and it breaks apart and reforms when the pool is calmed. The old stuff used to gum up filters and sides. There seem to have been some improvements over the last few years where this was an issue.

The liquid seems to stop evaporative heat losses when the surface is calm. For most residentials, this is at night when there is nobody using the pool and pump is off or if the pool is equipped with a variable speed pump, it is on its low speed setting, This is their target market.

IMHO, this is a good thing for free forms where using a solar blanket is difficult.



Well-known member
Dec 14, 2010
I tend to be VERY skeptical and would not have bought Cover Free. I went to a new Leslie's that just opened and since I bought a 3 Liter bottle of both Pool First Aid and Pool Perfect, I got a free Quart of Cover Free with purchase (Grand Opening Special plus 20% off).

I can't explain how these things work but I can say that Cover Free from Natural Chemistry works. I have always been impressed with their products and it looks like Cover Free works as well. I added it to the pool and had a 5 degree increase in temperature in just two days with it going into the 50s at night. I guess by not letting the night air steal so much heat it is actually able to allow the pool to heat up quicker due to retention.

As to it staying on the surface, it uses surface tension to stay on top of the water surface. It is not all pulled into the skimmer and pump unless you have many time more pump then you need and have a flushing vortex in your skimmer box. And since the dose is measured by your pools total gallons not surface area, what does get pulled in resurfaces when it re-enters the pool from the filter. Also the time its most needed is at night, so the first time you use it, use it at night, turn your pump off and then add the product to the surface. It is suggested to retreat once a week, which I do every Thursday Night.

We have been swimming for three weeks now and I have never been swimming this early without using the heater, dome, and a full solar blanket!