Solar blanket - 12 vs. 16 mil/color/cutting edges/steps

[ernie1959]

Have 18 x 36 (plus 4x8 steps) blue solar cover, not sure if 12 or 16 mil, most bubbles popped after 3 1/2 years, looking for replacement. Mine has "solid" edges (about 3 inch flat section on each side, so that you don't pop any bubbles or tear cover while pulling it off the reel.

In looking for a replacement I have several concerns:

1) Nobody seems to offer the flat edges on the sides. I'm concerned about grabbing a fistful of bubbles to pull a heavy cover off of the reel, thinking that they will pop, and the cover will tear.

2) Have a fairly heavy cover now, but not sure if I have 12 or 16 mil. Live in climate zone 5, so looking for good heat retention. Have Rocky Roller reel.

3) Pool is 18x36 plus a 4x8 step section. Everyone wants to sell me a 20x40 and tells me I'll just cut off one side. That seems wasteful and will leave me with a potentially jagged side (can't imagine it's easy to cut a perfect line). No better options?

4) Are there quality differences between sellers, or is this one of those products where they're all buying from the same supplier?

5) Some people say clear or silver are better for heat generation than blue. True or false? My wife really wants the blue "look" and has ruled out the silver, but might consider clear if our blue liner would show through the clear cover.

New to the forum and it won't let me search yet, so sorry if this topic has been discussed. Any help would be, well, helpful. Thanks!

[PoolDoc]

You can search, using the link in my signature. It's been discussed a number of times, but not with any clear resolution.

[ernie1959]

No "clear" resolution? Are you having fun with a new member?

How about all of my other questions? Anyone?

[PoolDoc]

No. Between now and July 4 my puns are likely to be an accident, rather than having fun.

[mas985]

From my own experience, clear seemed to heat better than blue and 12 mil lasted much longer than 8 mil. As for 16 mil, handling starts to become an issue and I haven't gone that route yet. Also, I think the 12 mil price point is a little better for the extra life.

Even though I have solar, my goal is to run the pump as little as possible especially on high speed and with the clear cover, I managed to do that with a few hours of run time except on colder days. The blue cover just didn't seem to add as much heat but it did seem to preserve the chlorine a little better. But it is kind of hard to do side by side comparisons because of the number of variables involved which is why there doesn't seem to be much consensus.

But from a purely theoretical point of view, here is how I would list the attributes of each cover:

Clear cover - Lets more sun energy through to directly heat the water but probably has a little more radiative heat loss back out so this cover should have the highest heat gain and perhaps the highest heat loss as well plus the lowest UV shielding for FC extinction.

Sliver Bottom - Lets virtually no sun in, sun heats the cover surface which is transmitted to the water via conduction and re-radiation (both directions) which will have more heat loss to the environment but the silver backing should help to reduce the radiative heat loss from the water to the environment. I would expect this cover to have the lowest heat gain but also the lowest heat loss and the highest UV shielding to preserve FC. But this shielding comes at a cost of higher cover temps during the day which could reduce the life of the cover.

Blue Cover - Lets more sun in than a silver/black cover but less than a clear cover so heat gain will be less than a clear cover but heat loss should be similar to a clear cover or slightly better. I would expect this cover to have a heat gain and loss somewhere between the other two and UV shielding between the other two.

All covers will probably have nearly the same R-Value so convection losses from the water to the air are probably similar.

So from these descriptions, the average water temperature (24 hr) may end up being the nearly same but the clear clover should give you a higher water temperature near the end of the day which is what I experienced.

But one of the reasons I chose a clear cover is because I have a SWG and when the water dries on the cover the salt stays behind and it is very white which is not as noticeable on a clear cover.

[ernie1959]

Thanks Mark. I guess I was hoping that there had been some definitive testing showing that one type has a better overall net heat gain.

So are all blankets now "bubbles to the edge" instead of the flat edge seams like my old one has? I know we have to tug pretty hard when pulling the blanket off the reel, and imagine popping a lot of bubbles as we grab a handful of blanket.

Since it appears I'll have to get a 20x40 blanket, and cut it, are there any tips on cutting? I assume I'll just cut one side after letting it sit on the pool a couple days to see how it settles.

[mas985]

I trim my cover so the edge has all bubbles but with the 12 mil and even the 8 mil, it isn't very easy to pop the bubbles. The cover is much thicker than bubble wrap.

Everyone has a technique for trimming but the one I found to be easiest is lay the cover over the pool so the cover is stretched over the coping to the water at about a 45 degree angle. I leave it there for a couple of days until the folds settle out. You can then take scissors and cut along the coping edge. Because of the 45 degree angle, the cover should then fall to the water level near the tile. Having a small gap between the cover and tile is not a big deal so don't worry too much about getting it perfect.

[PoolDoc]

Thanks Mark. I guess I was hoping that there had been some definitive testing showing that one type has a better overall net heat gain.

There has been no published definitive testing of ANY swimming products of ANY kind, at least not that I know of. The closest approach so far was the JSPSI, sponsored by Pool Chlor (more info here: poolhelp.com. There was a rather expensive plaster test project started maybe a decade ago, with much fan fare. Unfortunately, when the results started to come, they apparently were NOT pleasing to the primary sponsors, and were not published. The project still exists, sort of, but nothing much is happening and nothing at all is being published.

But, I'm working something I'm calling the Swimming Pool Research project. Right now, all I'm definitely planning is a comprehensive index of all peer-reviewed and otherwise technical literature (including MSDS and product data sheets) that relates to swimming pool products and operation. Right now, I have some domain names and about 8 Gigabytes of data, mostly in the form of PDFs.

Does your question mean I should list you as a possible sponsor, who I should hit up for support this fall, when I begin that?

[ernie1959]

Thanks Mark and Ben.

Ben, if by support you mean someone willing to take temperature readings, document weather stats, estimate "popped" bubbles, etc, YES. If you mean moolah, sorry, that goes to our church and thebabyfold.org (Sorry, shameless plug from a Board of Directors Committee Member!).

I also have an Ecosmarte pool and would be happy to post stats, chemical use (or lack thereof), etc about our pool.

[ernie1959]

Oops! I hope I didn't get censored for saying in passing that I have an Ecosmarte system. While waiting for my post to show up, I searched Ecosmarte to see if there were any topics and saw negative comments (not from users). Also, when asked for monetary donations (I think), I mentioned a specific, wonderful charity that helps kids, which I am honored to be a part of. Didn't mean to offend anyone, and hope this board doesn't function that way.

Anyway, maybe this post will show up. If so, I'm here because I have asked specific pool questions. I appreciate the responses thusfar, and reiterate my offer from the previous post to participate in studies of a variety of products, including solar blankets.

I wonder if we could set up a test of blankets using aquariums. Even 10 gallon aquariums side by side, but receiving the same amount of sun, each with a different color cover and the same thickness. They would need something to circulate the water to simulate the pool (standard filter on a low setting), and probably some sort of insulation around the sides to reduce extreme cooldown at night (at least where I live, in Zone 5). Temperature comparisons at the bottom and top of the tanks could be made morning, noon, and evening, over a period of days (hopefully a mix of sunny and cloudy ones). Does this seem valid?

Thanks!