Please "school" me in solar covers...

mogie

0
LifeTime Supporter
May 3, 2011
44
Rochester, MN
So I have just completed the baqua conversion and my pool life is beginning to look up! I do have a few questions about my solar cover though and I am hoping someone will be able to give some clarification...

1) Bubbles down, correct?

2) Due to neglect, frusteration, never ending algae with baquacil use, etc. my solar cover is in less than perfect shape and I am wondering if there is a point where a solar cover is no longer serving its function? I have left my solar cover in the pool during a couple winters and it seems like the bubbles aren't all holding air anymore. Furthermore, it has been caked with algae several times since and it seems like algae has even possibly gotten into the bubbles. Yesterday, I scrubbed, as well as pressure washed both sides with bleach. It looks pretty good, but some sections definitely look more beat up than when I intially bought my house and used the cover my first year.

3) Should I leave the cover on at all times while I am not in the pool?

4) Does having the cover on decrease the amount of FC consumed by sunlight?

I think that's it for now. Thanks guys!

Matt
 
1) Correct!

2) My personal opinion would be to replace it with an 8 mil opaque cover.

3) Yes, unless, the water is getting too hot, then you'll want to leave it off so the water will cool a bit.

4) If it's an opaque cover it does. I have a clear cover and don't notice much difference with it on or off.

Come back when you have more questions. We love questions! :)
 
If it is damaged it will also begin to shed bits of the cover/popped bubbles that will get into your filtr system
 
I agree with Bama, though my clear cover is so efficient that we have overheated several times already this year (which for us is over 88 degrees F). I got my 20 x 40 clear for under $250, shipping included. It is 12 mil.
 
What is the difference in mills? I live in MN where there tends to be a cold spring. Right now, my pool is hovering right around 70*, which is a bit on the cool side in my opinion. What do people typically leave there temps at?
 
Around 8 mils is the general, then there are 12 and 15. Heavier covers. I have had some really heavy covers in the past, the heavier it is the more work to pull off and on. That being said, the heavier cover is obviously more insulation. Do NOT count on your solar cover to heat your pool - they do not heat pools, except maybe the top couple of inches of water. What they really do is HOLD the heat in, prevent evaporation. If you want to heat your pool cheaply, get some solar panels. You can see an increase of several degrees in a few short days with sun. Our pool is standing at 80 this morning, where on Monday it was 71 after storms and cooler temps. We expect quite a lot of heat from that sun today so should see an impressive jump into the perfect zone.
 
Mogie, I would recommend getting a new cover too. We got one that is blue on the top and the underside is silver. We've had it going on 7 years and it's just now starting to wear out to where this will be our last season with it. We have an odd shaped pool so we had to get a bigger cover in order for it to be long enough. So we got one that was twice as big as needed and cut it down the center in half. We still have the unused half in our garage which will start using next season.

I find using a solar cover at night really helps hold the heat in.
 

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My cover is also in need of replacement. The millions of tiny blue bits and pieces in the filter are a good indication I've waited too long.

While I understand that the cover acts to insulate and minimize heat loss, Mine actually keeps the top foot of water pretty toasty on sunny days, so Why wouldn't they make them out of Black material to maximize the heat absorbtion? Am I missing something?
 
For a solar cover to help warm or hold heat in a pool, it needs to perform two functions:

1. Limit evaporation cooling by providing a shielding layer between the air/wind and the water surface. Any solar cover color or mil thickness will do equally well for this. Very thin saran wrap would also work as well for example. This might be the most important function of the cover in windy areas or high evaporation loss areas such as deserts and hot climates where a pool can lose 10 deg or more a night. For most effective use, the bubble side needs to be in the water which helps the top smooth surface of the cover float slightly above the water line which limits conduction cooling of the water from the wind cooled top surface of the cover.

2. Allow sunlight to penetrate through the cover to heat the water, pool surfaces. This is where the thickness/color/material play a part in how effective the solar heating is. Most of the heat energy conveyed by sunlight is in the near to mid infrared (IR) bands around 1-3um wavelengths. These wavelengths are outside our vision range and cannot be seen by the human eye which stops at wavelengths longer than 0.7um. So what the solar cover appears like to your eye (visible light) may be completely different to the infrared light. There are quite a large number of plastics and materials that you cannot see through but pass the infrared light with no loss and vice versa. Since most covers do not list how well they transmit infrared light, you have to rely on the description to judge their effectiveness. If you know the material the cover is made of, you may be able to find its transmission % in the IR and use that to compare against a different material.

I have tried blue and clear solar covers and in my experience, the clear cover provided slightly more heating effect than the blue cover. I have no data to back this up, my subjective opinion only. I will say that the blue cover does look more attractive on my pool than the clear does.

Some of the more expensive cover have a metallic layer (often aluminum) sandwiched between the plastic layers. Metals are very efficient reflectors for infrared light so covers with a metallic aluminized layer in them will block (reflect) most infrared light from passing through the cover. For this reason I would not buy the covers that contain the metallic layer if you are wanting some solar heating effect. These metallic layer covers will excel in retaining heat since the metallic layer will help hold whatever heat was in the pool from radiating out. So if you heat your pool via gas or solar panels only and don't use the sun for direct heating, and want to hold that heat in overnight, then the metallic layer cover might be the best choice.

Thickness will also play a small part as a thicker material will tend to absorb more and transmit less but this effect is small and the increased durability of a thicker cover might be more valuable. 8 mil thickness appears to be the starting point and they go up to 16 mil thickness and beyond. I have tried 8, 12 and 16 hoping to get more seasons out of the thicker material but ended getting about 2 years no matter what thickness I used. 12 seems to be a good compromise on durability and price. The thicker covers are heavier to drag in and out of the water.

Expect to replace your cover every two years, maybe longer if you are careful handling the cover when removing it and installing it. My covers tend to start shedding bubbles due to being dragged over the brick edges of my pool during removal, install after being aged by sunlight and chemicals for 2 years.

I hope this helps explain a little about how they work.

Steve - Optica
 
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