Automatic Retractable Pool Safety Covers - Pros & Cons

[dreampool]

We are finalising an inground pool - approx size 30X14 feet. We are debating on the pros & cons of installing a retractable pool cover. The contractors are giving mixed messages. There are a no. of things to consider - pool safety, cost, water temp & insulation, ease of keeping the pool clean, shape of the pool. Safety is not our biggest concern since our kids are older & good swimmers. The cost of installing solar panels vs. pool cover are comparable. We live in N. Calif. Does the water stay significantly warmer with the help of the pool cover? I know that it stays cleaner. But, won't all the new pool gadgets - pool sweeper, vaccum & filter, etc. help keep the pool clean & low-maintenance anyway? Would the salt water system corrode the rails of the automated cover? Would it help to have rails made out of brass (or is it bronze?)? I would really appreciate any advise/ experience in this regard.

[07airstreamtt]

I would also like to know about retractable pool covers. We will be building an inground pool soon and need to plan for a cover. One thing for certain, we will not be building a kidney shape like we have at our house now. It will be a simple rectangle to make covering easier.

[chem geek]

I have an automatic electric safety cover for a 16'x32' rectangular pool (16,000 gallons) using an undertrack from Pool Covers, Inc. as shown here. If your in-ground pool was designed to have an automatic cover by having coping with an overhang, then the track can be under the overhanging coping and the cover itself can be hidden in a vault at the end of the pool. Otherwise, you would need to use a track on top as shown here (other options are shown on the website).

The cover definitely keeps the pool far cleaner -- we have a cedar tree nearby that dumps cedar needles towards the pool. However, you have to clean off the cover (with a brush) anyway unless you plan to periodically clean the vault where the cover is stored (by keeping the cover clean, the vault only needs to be cleaned once a year). So there is still labor associated with keeping the pool clean, even with a pool cover.

As for insulation, an automatic cover is thinner and less insulating than a bubble-type cover. I estimate that it retains heat only about half as effectively as a bubble-type cover. Basically, both types of cover eliminate evaporation which is the largest component of heat loss, but heat is still lost through conduction/convection especially at night with cool air (especially with wind). I live in northern California (just north of San Francisco) and the pool (starting at 88F) loses about 3-4F at night in the swim season (with 50-54F overnight low temps). Without the cover on, it loses around 6-7F. Based on other pools in the area using bubble-type covers, they seem to lose 1.5-2F overnight.

The other factor to consider is that the automatic covers are generally opaque to sunlight. Though this prevents chlorine breakdown from UV in sunlight so significantly reduces chlorine demand, it also prevents heating of the pool from sunlight, especially compared to a relatively clear bubble-type cover. A white plaster pool without a cover absorbs about 60% of of the sun's energy. I don't know how much light gets through a clear bubble cover, but most pools are able to rise in temperature significantly so I would guess that at least half of sun's energy gets through with a somewhat clear bubble cover. A pool with an average 4.5 foot depth and the amount of solar insolation in July in the Bay Area in July raises the pool temperature by 4.7F with no cover, but evaporation of 1/4" lowers it by 4.9F so without a pool cover there is very little temperature rise (above average day/night temps).

A solar panel heating system will be about 80% efficient. A system that is 100% of a pool's surface area will increase the pool temp by 0.8*4.7 = 3.8F per day. So combined with a clear bubble-type pool cover, this is a significant heating rate. With an electric opaque cover, it mostly keeps up with overnight loss. The bottom line in our own pool is that during peak summer you can heat the water so that it varies from 90F peak during the day and 87F at night in July, but in May/June and August/September it varies between 88F peak during the day and 84-85F at night. Right now in October, the pool would settle down to around 80-84F except for a small rise during the recent Indian Summer.

So the bottom line is that for maximum heating, a combination of solar panels with a clear bubble-type cover is the most effective. A solar panel system (with 80+% of a pool's surface area) with an electric opaque safety cover would be next most effective. A pool with a clear bubble-type cover and no solar system would be a little less effective. A pool with no solar and no cover would be much cooler.

As for having higher salt levels due to a saltwater chlorine generation (SWG) pool, the higher salt level is more corrosive to aluminum especially. If you have a pool cover with an aluminum header bar that touches the water, then it can corrode. Or if you have a track on top of the coping then splash-out can corrode the track. These problems are most easily mitigated by using a magnesium sacrificial anode attached to the bonding wire connected to the aluminum.

In our situation, an automatic cover was a requirement since rolling up and pulling out a bubble cover would not be easy for my wife. If you are going for maximum heating, then get a solar system with a clear bubble cover; if you are going for convenience, then go for a solar system and an electric safety cover. If you have to choose between a solar system and an automatic cover, the solar system is definitely the way to go because the automatic cover alone will prevent your pool from getting heated (except by gas).

Richard

[07airstreamtt]

Thanks Richard for the reply. A bit delayed thanks, but I appreciate it very much. I will print it and read it over. We close on the house where the pool will be built next week. Thanks again. Pat

I have an automatic electric safety cover for a 16'x32' rectangular pool (16,000 gallons) using an undertrack from Pool Covers, Inc. as shown here. If your in-ground pool was designed to have an automatic cover by having coping with an overhang, then the track can be under the overhanging coping and the cover itself can be hidden in a vault at the end of the pool. Otherwise, you would need to use a track on top as shown here (other options are shown on the website).

The cover definitely keeps the pool far cleaner -- we have a cedar tree nearby that dumps cedar needles towards the pool. However, you have to clean off the cover (with a brush) anyway unless you plan to periodically clean the vault where the cover is stored (by keeping the cover clean, the vault only needs to be cleaned once a year). So there is still labor associated with keeping the pool clean, even with a pool cover.

As for insulation, an automatic cover is thinner and less insulating than a bubble-type cover. I estimate that it retains heat only about half as effectively as a bubble-type cover. Basically, both types of cover eliminate evaporation which is the largest component of heat loss, but heat is still lost through conduction/convection especially at night with cool air (especially with wind). I live in northern California (just north of San Francisco) and the pool (starting at 88F) loses about 3-4F at night in the swim season (with 50-54F overnight low temps). Without the cover on, it loses around 6-7F. Based on other pools in the area using bubble-type covers, they seem to lose 1.5-2F overnight.

The other factor to consider is that the automatic covers are generally opaque to sunlight. Though this prevents chlorine breakdown from UV in sunlight so significantly reduces chlorine demand, it also prevents heating of the pool from sunlight, especially compared to a relatively clear bubble-type cover. A white plaster pool without a cover absorbs about 60% of of the sun's energy. I don't know how much light gets through a clear bubble cover, but most pools are able to rise in temperature significantly so I would guess that at least half of sun's energy gets through with a somewhat clear bubble cover. A pool with an average 4.5 foot depth and the amount of solar insolation in July in the Bay Area in July raises the pool temperature by 4.7F with no cover, but evaporation of 1/4" lowers it by 4.9F so without a pool cover there is very little temperature rise (above average day/night temps).

A solar panel heating system will be about 80% efficient. A system that is 100% of a pool's surface area will increase the pool temp by 0.8*4.7 = 3.8F per day. So combined with a clear bubble-type pool cover, this is a significant heating rate. With an electric opaque cover, it mostly keeps up with overnight loss. The bottom line in our own pool is that during peak summer you can heat the water so that it varies from 90F peak during the day and 87F at night in July, but in May/June and August/September it varies between 88F peak during the day and 84-85F at night. Right now in October, the pool would settle down to around 80-84F except for a small rise during the recent Indian Summer.

Thanks Richard! A bit late with this thanks, but will print your reply

So the bottom line is that for maximum heating, a combination of solar panels with a clear bubble-type cover is the most effective. A solar panel system (with 80+% of a pool's surface area) with an electric opaque safety cover would be next most effective. A pool with a clear bubble-type cover and no solar system would be a little less effective. A pool with no solar and no cover would be much cooler.

As for having higher salt levels due to a saltwater chlorine generation (SWG) pool, the higher salt level is more corrosive to aluminum especially. If you have a pool cover with an aluminum header bar that touches the water, then it can corrode. Or if you have a track on top of the coping then splash-out can corrode the track. These problems are most easily mitigated by using a magnesium sacrificial anode attached to the bonding wire connected to the aluminum.

In our situation, an automatic cover was a requirement since rolling up and pulling out a bubble cover would not be easy for my wife. If you are going for maximum heating, then get a solar system with a clear bubble cover; if you are going for convenience, then go for a solar system and an electric safety cover. If you have to choose between a solar system and an automatic cover, the solar system is definitely the way to go because the automatic cover alone will prevent your pool from getting heated (except by gas).

Richard

[4serendipity]

One major advantage of automatic swimming pool safety covers that is often overlooked:

When you sell you property you wil be selling to a limited market of people who will buy a house with a pool. having an automatic safety cover is a huge selling feature for the house and pool since it can help to alleviate some of the risk associated with having a swimming pool in your backyard.

The cover itself is a no brainer - if you can afford an automatic safety cover then you should buy one. They are very expensive even by swimming pool standards but have huge benefits on the enjoyment, convinience and costs associated with owning a pool.

I hope this information is helpful.

S

[Lips Malloy]

I am building a new pool, a 10' x 37' rectangle with spa within footprint, and will have an automatic pool cover, the underdeck recessed mount that completely hides the housing. My question is, which brand is the best? I was going to go with the PCS Infinity 4000, but the pool builder swears by CoverPro. I am having a hard time finding end-user reviews of the various brands. Does anyone here have personal experience, or can you point me in the right direction? Thanks for any advice.

[chem geek]

I have an Infinity Undertrack from Pool Covers, Inc., but since I've never had a CoverPro I can't give you a comparison. I will say that I've had to replace the cover every roughly 4 years and some of the hardware after around 7 years. It looks like CoverPro does installations in southern California which is why it wasn't an option for me as I'm in northern California.

[Lips Malloy]

Thanks for the reply. My pool builder has been building high-end pools since about 1965, so I guess I should trust his judgement. I noted upthread you talked about bubble covers and solar, and in So Cal, they both tend to heat a pool too much. He told me I'd be adding ice cubes to the pool with solar, and it wouldn't heat up the spa part enough. So I am going with a High Efficiency heater, and a 4 speed pump that is also energy efficient. I am looking forward to having a pool cover because I have a pepper tree that dumps leaves into the pool whenever a wind kicks up. I am also going with a salt water chlorinator system. I think the Cover Pro system uses stainless steel rather than aluminum. Do I have to worry about corrosion?

[chem geek]

High quality stainless steel will be more resistant to corrosion from salt water than the aluminum. Normally the main aluminum parts are the tracks and the header bar, but unless they are immersed in the water then they should be OK (see this link for an example of salt splash-out corrosion on an aluminum over-track for an automatic pool cover). For those with aluminum that is immersed in the water, the use of a sacrificial zinc (or magnesium) anode buried in moist soil will help protect the metal. If only stainless steel is being used in your case, then I wouldn't worry about it, though you should ask the builder since he must have experience with such systems.

[Lips Malloy]

Thanks for the info. Here are a couple pix of what the pool will look like, though I will be using 3 Rivers flagstone instead:

[chem geek]

Very nice! For our pool we used hand-troweled cement made to sort-of look like flagstone. Of course, when looking at the real thing, there's no comparison.

[Lips Malloy]

Wow, that looks very nice. I didn't know cement could look so good! My old pool took up so much of the backyard, and I had cement everywhere except a brick patio and a little bit of grass. I hated the cement! Plus it had holes and hardware where I had to install a safety fence. I am going with a removable safety fence that can be set in the grass around the coping, so you don't see the holes. I only plan to use it for the inspection, and again when I sell. Honestly, an automatic pool cover should be enough. The building codes here are ridiculous.

I'll be putting in about 1500-1900 SF of flagstone, some of it set in sand and the rest as pool coping and patios. It will cost an arm and a leg, but I will get at least double and probably much more what I'm putting in on this project when I sell. I'm also putting in a retaining wall that will widen the side yard, and a waterfall/pond feature. Here's the site plan. The property extends about 2-3 times as large as the pad, downslope, overlooking a canyon. I wanted to make the usable space seem larger. A narrower, linear pool and the curving retaining wall (where there is currently a side yard slope) will make a huge difference.