Heat Your Pool With Solar Lily Pads

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Introduction: Heat Your Pool With Solar Lily Pads

There's no doubt that a Solar blanket can really help to heat your pool. They turn your pool into a greenhouse, letting sunlight in, trapping the heat inside. They also significantly reduce heat by evaporation, and also to a limited extent prevent heat loss by emission. Studies have reported that with 6 hours of sunlight, a good solar blanket can heat your pool by 10-15F (6-8C). https://blog.intheswim.com/how-effective-are-solar...

However, despite their ability to heat your pool for free, many people are reluctant to use them because of the safety risk. If a child or a pet jumps into a pool with a solar blanket cover still on, they can get wrapped in the blanket or can slip under it, and can drown.

Instead of covering your pool with a solar blanket, these solar lily pads are a safer alternative that reduces the risk of harm. By having lots of smaller floating pads instead of one large blanket, anyone falling in the pool will slip between the gaps, and similarly can surface between the pads, or move it out of the way. Only 80% of the pool is actually covered, but it still really makes a difference, and that 20% gap is adding safety.

Note, nothing can completely remove the risk of harm around a pool. This is designed to make it "safer", but not "100% safe".

Supplies

  • Hula hoops. You need enough to almost cover the pool. I have an 8m x 4m pool, so I bought 32 90cm hoops (i.e. 8 x 4). Why not 1m hoops? Because you are going to need some wiggle room or it will be a nightmare to get the hoops in the water. I used these.
  • Enough solar blanket to cover your pool. I used the SolGuard GeoBubble from here.
  • 6mm x 10mm Fir tree car trim panel clips - at least 6 per hoop (I actually could only find 6mmx14mm and had to trim the ends off them all). I found some on eBay.
  • Some fiberboard to make a template - at least 90cm x 45cm

Tools

  • Drill with 6mm bit (to match the fir tree clip diameter)
  • Stanley Knife
  • String
  • Sharpie
  • Jigsaw

Step 1: What You Are Aiming For

Here's a picture of what you are aiming for to give you an idea of the end result. We are cutting the solar blanket into circles, and fastening it to the hula hoop.

Step 2: Cutting Your Solar Blanket

To cut the solar blanket, you're going to need a template. I tried first of all with just using a knife on a piece of string, like a compass. It didn't work - horribly messy edges. So, find a piece of fiberboard or similar, and make a template. Make it about 3cm larger in diameter than your hoops - you're going to need it to go over the edges or the fasteners will be too fragile. Get a sharpie and a piece of string, and draw a nice circle on the board (or a semi-circle if, like me, you don't have a big enough piece. Then get out a jigsaw and cut the template out.

Next, start cutting circles. Put your template down and cut around it with a Stanley knife, or other heavy-duty knife. I did it on the lawn so that I was able to easily kneel on it all and cut without fear of damaging whatever was underneath. Don't leave too big a gap between the circles or you won't have enough material.

Step 3: Build the Hoops

Once you've cut your first circle (not the last - let's make sure it fits when you've only cut one), lay it on top of the hula hoop, bubble side up. Hopefully it's going to just go over the edge all the way round. Get your drill and drill a hole through the bubble cover and the hoop together. Pop a clip in, and then start drilling more holes. Drill one and clip one hole at a time. If you try to do more, it's pretty much guaranteed to move between holes and won't line up.

If the hoop squashes as you put the clip in, get a pair of grips to squash the hoop horizontally and push the clip in then. Once you have 6 clips it should all be sturdy. If you can get a good price on the clips, put 12 in - it will be easier to move the hoops in the water later on.

Assuming the first hoop was all perfectly sized, cut out the remaining circles and get clipping.

Step 4: Throw Them in the Water

Once it's all done, throw those hoops in the water, bubble side down. They'll increase the heat in your pool for free.

I did a test to see how much - I measured two similar days - one day with the hoops in the water. The water went up 2.5C with the hoops on (and the heat pump on). The next day was the same starting water temperature and the same air temperature. I left my solid slats cover on, which is more insulating against heat loss, but doesn't have any solar gain. The pool temperature went up 1.5C, again with my heat pump on. So the 1C heat rise is not the amazing 5-8C rise that is seen in some places, but I figure it will save me money over one season, and it will be better for the environment too.

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    23 Comments

    1
    woodlab
    woodlab

    1 year ago

    I’ve never had a pool but I’ve always theorized that putting some black mats on the bottom would heat up a pool. Or just rig up a circulation pump and a black hose along the side of the pool. Has anyone ever tried something like that?

    1
    BardP
    BardP

    Reply 1 year ago

    I did something similar to heat up the kiddie pool when the kids were small. The pool had a white bottom to keep it from overheating. When I first filled it up, I put a couple of black garbage bags on the bottom to retain more solar heat. Some rocks to keep the bags from floating up. Once the pool was warm enough, I removed the bags.

    Leaving the black plastic bags on the top did not work. The plastic gets hot, radiates heat back and does not transfer much heat to the water. When they are under the water, any heat absorbed by the bags gets transferred to the water immediately.

    For a pool I could imagine a set of lily pads like the ones described in this instructable combined with a sheet of black plastic rolled along the bottom of the pool. A simple roll of black plastic sheet would work for heating, but I am not sure if it would hold up with repeated rolling/unrolling. Maybe a more sturdy material like a pond liner would be required.

    0
    wingerr
    wingerr

    Reply 1 year ago

    Seems a black solar cover would be more effective for heating by absorbing more of the radiation instead of reflecting it back up to the sky

    0
    DavidS1168
    DavidS1168

    Reply 1 year ago

    I personally think that deep blue tiles look a lot better and it'll collect more heat.

    0
    KJMitseff
    KJMitseff

    Question 1 year ago on Step 4

    What kind of clips are used

    0
    millmore
    millmore

    Answer 1 year ago

    I used fir tree clips

    1
    rnorton2
    rnorton2

    1 year ago on Step 3

    i like this a lot lugging that huge pad around and getting help spreading it out and rolling it up never happened

    0
    DavidS1168
    DavidS1168

    1 year ago

    Cool. Now, should you use square frames you'll achieve the same safety result with 100% coverage.

    0
    fCauneau
    fCauneau

    Reply 1 year ago

    yep ! I did one on a square frame basis : much better... especially if you think that the only advantage of this device is the blanket effect (and a small
    greenhouse effect, but no matter the blanket is "lense" textured or not).
    Definitely, the solar energy collected by your basin is much better kept when
    you isolate the water surface from convection toward cold air. This is
    the basic advantage of this device. At the end, the so-called "lenses" effect doesn't bring anything in fact : this because the lenses do not collect energy on a larger surface than the one of the basin.

    0
    millmore
    millmore

    Reply 1 year ago

    Sounds interesting. What did you make the square frames out of?

    2
    fCauneau
    fCauneau

    Reply 1 year ago

    PVC tubes and PVC plumbing 90° for the corners (forget any aesthetics) : I did it long ago for a children pool, when my children were young, and I was afraid like you if they could get embedded in the solar blanket. As I sayed, the advantage is you dont have losses as the covering is total. But I must say that your "Lily Pads" offer a much better look !! I must say also that mine finished under water surface : the PVC were of course filled-up with water but the pieces of solar blanket ended filled-up with water too ;-)

    0
    millmore
    millmore

    Reply 1 year ago

    That's a great idea.
    I do get water in my hoops sometimes too, but it drains out when I lift them out of the water

    0
    fCauneau
    fCauneau

    Reply 1 year ago

    Yours is much much nicer than was mine... if you think about improving surface cover, maybe possible to add smaller lily pads bounded to each big pad... like in apollonian circles : you could get a near 100% cover, without losing the aesthetic of your work !!

    0
    SteveJ113
    SteveJ113

    Reply 1 year ago

    I was thinking the same thing.. Or even square pieces of the bubble cover overlapping with just the same hula hoops (so the diameter of the hoop is the length of the side of the square of bubble cover). I have been thinking of doing something similar - We have an above ground pool, and our full bubble cover does have a very noticeable impact on evaporation and heat loss at night, which may be even more important than capturing new heat during the day. This added safety would be good. They do make these commercially but they're relatively expensive compared to the plain cover.

    2
    millmore
    millmore

    Reply 1 year ago

    It wouldn't hurt to a square sheet on a round hoop. If it's awful or annoying to use you are free to trim it afterwards.

    0
    SylvanB
    SylvanB

    Question 1 year ago

    Clever idea.

    Have you experimented with the bubble side up vs. down against the water? Probably doesn't make a lot of difference, but it seems adding a small air gap might be helpful. The R-value of that bubble cover is not very large.

    I've also wondered if something similar to but lighter than the balls used to cover some California reservoirs would help heat a pool and perhaps could be left in all the time. (Used for algae prevention.)

    0
    millmore
    millmore

    Answer 1 year ago

    I haven't personally experimented with the orientation. I read that it needs to be bubble side down - that creates an air gap between the cover and the water. That gives you some insulation, and allows hot air to build up.