I have to agree, Consultant.

The night before last the outside temp was in the teens and the GH was 54F with only one of the three heaters running. Last year both heaters were required to keep up with those temps.

Ice was present last night on the southern GH glass where there was no pool cover, but the north, west, and east sides with the cover had no ice at all. Last year without the cover, the ice frosted the glass all the way around the GH.

Still, I am looking forward to this weekend and next week's sunny highs in the upper 30s and 40s. SB

I've also noticed that the cover doesn't seem to block too much sun. It was sunny here today. I didn't have my light meter with me, but it was bright while I was in the greenhouse. It got to 83 degrees, while it was 25 out. Generally, the heater doesn't have to come on for several hours after the greenhouse is no longer in the sun.

I finally got my solar cover on too. Have to agree it makes a world of difference. My GH stays at least 10 degrees warmer than with the bubble wrap I have used in previous years. Thank you so much cactusfreak for sharing your great idea with us all.

PQ

I think the pool cover company should be paying Cactusfreak a commission for all the covers that have been sold as a result of this forum! :) I just got mine installed the other day too here in chilly Ontario. See the Pool Cover Makes a Great Sail thread....

I just may have to buy one for next winter...

I do need to invest in one. Are the ones ya'll use clear or blue colored? What mil do you recommend? I found a website selling some that are very affordable but they light blue colored.

Also, how big does one get? Do you worry just about covering the top or get one large enough to cover the sides?

Nancy

Here is a link that might be useful: Blue cover

Get clear, not blue. I have north, east and west sides covered, but others have only a portion of the sides covered.

I got 20' x 40' size. I cut off 10' x 20' piece for the north wall and then put the remaining 20' x 30' across the ridge of the GH.

{{gwi:308798}}

My greenhouse is a little 6x8 Harbor Freight model, so the smallest pool cover (clear) was large enough to essentially "giftwrap" the entire structure all the way down to the foundation. The cover on the south wall/roof is cutting down somewhat on the sunlight, but it seems to be moderating the high temps we were getting on sunny days. The plants still seem happy enough, showing new growth and flowering without getting leggy.

Get the Magni-Clear. It's thicker and let's in more light.
Make sure it's rectangle and not round. I got the largest I could without paying freight charges. I also bought 2 instead of getting one larger. Less shipping fees and not as big and bulky to handle. I later bought a 3rd one for the north end wall.
You also have to think ahead to spring when you take it off and store it. It was easier to store 3 instead of one giant one and not as heavy. Also I think it's best to store out of the sun and in a cool place to keep the plastic from breaking down too soon.

Here is a link that might be useful: 20x40 Magni-Clear $157.99 Shipping and Handling will vary.

Funny as I was going to post the same topic.
My HFGH is 43 deg, with outside temps at 10 deg. & a solor pool cover. It's just tossed on & it's not a snug fit. Need to get tie downs and would like to add weather stripping around the panels. I also am using only one heater.

I insulated the foundation & floor, & the N wall. And want to insulate half the roof. With these few extra improvement I bet U I could keep it in the 50s with single diget temps.

Birdhope, looks like we've got similar results. 34 outside and 70 in the g'house on a sunny and calm day. We went for the snuggest fit we could, to avoid the "sail" issue. I much prefer getting it done on a mild sunny day to waiting until it's necessary to stand out in cold, wind, freezing rain and maybe the dark to get it secured. Discomfort is a major motivator for me. The pool cover (magni-clear) was heavier and stiffer than I realized it would be, but that's probably for the best.

Didn't insulate the floor or foundation - will probably try to retrofit that, and, like you, add some insulation to the north roof.

My cover came very well packaged - we opened carefully so as not to damage the cover and preserve the bags for storage.

The other issue was how well it would do with snow. We got a foot of snow & the GH was warm enough to melt it right off. Didn't have to brush it off.

AGardenStateof_Mind what about your night temps?

Thanks for the link Cactus.

I believe the low so far is 22 degrees, not considering wind chill factor. We've had some days, sunny and cloudy, where the wind chill has brought it down to 11/12. This is colder than the norm for us. Single 1500 watt convection heater has maintained 50 degrees*. Our first snowfall was 6" of heavy wet snow - typical for coastal NJ - it came down fast but melted right off. Will have to wait to see what happens if we get a heavy snowfall in really frigid weather. Perhaps ignorance is bliss, but I would expect that, if anything, a well-secured pool cover will help to evenly distribute the weight of the snow.

As for installation, we were down to the wire with a storm closing in. We rolled the long edges around some treated 1x4's we had on hand, and then screwed that right to the 2x10 foundation. Might have to look into something else for future, as I don't want to ruin the foundation with repeated application/removal of the cover. The ends are secured with all-weather tape and clamps.

*The only exception was a run of ~44-degrees at night which I later discovered was because someone had messed with the heater and turned the thermostat back to the no-freeze setting. So be watchful if you have children, teens, or others who like to fiddle with things.

Cactus, thank you for the tip on the pool cover.

Diane

We had about 6 inches of snow a few days ago and it slid right of the roof. I think the smooth surface of the pool cover helps in that regard. The greenhouse has still been holding at 60 at night, even when the temperature has been down to 13.

I'd also like to thank cactusfreak. I would never have thought of using a pool cover if I hadn't seen her posts. The pool cover is going to save me a ton on heating costs.

Add my thanks to Cactus for the pool cover idea. The pool cover over my double wall poly glazing has really cut down on the amount of time my electric heaters are running.

Juanita

How do you manage your roof vents on a sunny day?

M

Just got the cover on this weekend. Then had to go back out about an hour later and turn the thermostat down. It got really toasty in there. Last night at 11 pm it was 21 degrees out and the greenhouse was still 57 degrees. Plants are happy and so am I.

With the double HF my 12' x 20' lacks a little on the sides. About 2'. I saved all the heavy duty bubble wrap that my bosses paintings were shipped in from Germany and I plan on using that to cover that bottom area. It won't be pretty on the outside but it will still be heaven on the inside.

I agree with everyone else. Thanks Cactusfreak!! I thank you and my pocketbook thanks you!

Cindy

Just as another follow-up...It got down to 3 degrees here last night and my HFGH was at 57. It normally is at around 59. I think that's tremendous, considering I only have a single electric heater.

All,
I want to second marquisella's question. How do you manage the roof vents? At least in OH, we get some warm spells that make it necessary to open the vent in my HFGH even in Jan/Feb.
Best Regards,
Brian

Apparently most of you are covering HFGHs or relatively small structures. Anyone have any comparison of the pool cover with inflated double layer plastic film? Anyone know if the wire-lock will work to secure it? I'm not knocking it...actually very interested but I want to cover standard commercial structures- 96 ft. long. Anyone have a reliable means to splice a few sections together? Do you all remove it for the summer or can it remain year round?

Wirelock can only work if the tracks that they lock into have enough space.

On our little hoop house, I have double poly. The wirelocks work fine. But when I put bubblewarp on and some of its plastic gets sandwiched, it can be difficult to get the wire to.... well... lock in! LOL );o And yes, the bubbles are popped at that location! hehehehe

BrokenAppleTree and Marquisella- I have a automatic, heat activated, roof vent in my greenhouse. My pool cover reaches all the way from one side, over the roof and down the other side. I just cut a square hole in the pool cover, over the window the venting mechanism opens. I bought the device from Lee Valley-you add it to your own window. We used a small bathroom window we found in the bargin bin at Home Depot.
This roof vent has been a life saver. We placed it near the roof ridge and when it opens the heat flows out very quickly.

Here is a link that might be useful: Lee Valley Heat Activated Window Opener

Does it heat the swimming pool or does keep the heat in ?

That's a very important question, does it heat the pool by conducting or magnifying the sun's heat, or does it hold the heat in because it is like an insulator?

If it is an insulator, it sounds like what I need to keep the greenhouse cool in our unbearable 100 degree summers here. Using it with both ends open and in conjunction with the mister.

Does anyone know which principle this cover works on?

Thanks.

Connie

Just a few general comments on solar pool covers and bubble wrap. Some of the light energy from the sun is converted to heat when it hits a solid material. That could be your plants, floor, benches, etc. in the greenhouse or shade cloth outside the GH. Since most of the light goes through solar pool covers/bubble wrap, they do not magnify ,or reduce meaningfully, the incoming sun light/heat. Once the light is converted to heat, these materials can help in reducing the escape of the heat that has been generated inside the greenhouse, useful in winter, but obviously not in the summer.
The effective way to reduce heat coming into the GH is to reduce the incoming light energy before it is converted to heat inside. The trade-off is that plants need light for photosynthesis. It is easy to block 100% of the light energy/heat coming in with 100% black shade cloth or similar materials, but then the plants would not be able to grow. It comes down to a matter of balance- enough light for the plants and reducing heat load.

how strong is the pool cover? can you use it without any glass/plastic underneath? Say with a wood frame supporting every couple feet? Would it hold up to something like hail?

If you have a horticultural poly cover on your greenhouse you should be very careful.
Most pool covers are made from pvc polymers which contains 56.8% chlorine by mass. The chlorine will be absorbed by your poly.
It acts as a solvent, which deactivates the UV stabiliser and causes the film to degrade well before its design life.

"It [chlorine] acts as a solvent, which deactivates the UV stabiliser and causes the film to degrade well before its design life."

Could this be why some are finding small holes in the polycarbonate glazing on our greenhouses? I thought mine was fine, but just discovered a few tiny holes here and there ... only on the exterior of the roof panels, more on the south-facing roof than the north-facing roof.

The solar pool cover is so helpful in conserving heat through the winter. I wonder if there's any way to protect the poly ... shade cloth, car wax, etc?

Hi
I doubt it would have the same effect on polycarbonate.
The pin holing doesn`t seem to fit the bill of the uv stabiliser going south, that would probably manifest itself as premature aging similar to the hort poly.

Here is a fairly comprehensive list for polycarbonate resistance.
It seems that hydrocarbons will damage it. Pouring coca cola on it could be detrimental over time but you can safely cover it in chocolate if you wish :)
http://www.palram.com/Media/Uploads/Chemical_Resistance-Polycarbonate.pdf

I have to share these new summer covers I found on a pool internet site the other day. They are simple to use...ez on and ez off...and keep all the gunk out of the pool. The site is BackyardCityPools.com I have never seen these before.

Here is a link that might be useful: http://www.backyardcitypools.com/Pool-Covers/leaf-nets/Summer-Cover-Pool-Leaf-Nets.htm

Is there anyone out there who lives in the Washington, DC area who has experience putting together a 5x6 HFGH who would be interested in helping me put together mine? Not for free.

So do you all have a green House to protect durring the winter chill or is it for other benefits as well ? Do you all recommend them in southern Calif. as well. Other than freezing protection do you see other benefits to your plant collection?

Thanks yall,
Greg

So do you all have a green House to protect durring the winter chill or is it for other benefits as well ? Do you all recommend them in southern Calif. as well. Other than freezing protection do you see other benefits to your plant collection?

Thanks yall,
Greg

Has anyone tried putting up a solar pool cover on the inside of the greenhouse? Do you know if it will help retain the heat inside? I'm just getting my greenhouse set up now and am trying to prepare for the winter months now. Any help appreciated!!

I just ordered a 16x28 ft solar pool cover to cover my 16x12 green house the rest of the winter.
Last night it was 9* and the green house went down to 37* with a 240 volt electric heater. Not too bad.
Should I make the space between the pool cove and plastic sheeting air tight or just use some sort of grommets to tie down the cover? White sort of grommets should I use if I go that route?

I have installed my solar pool cover over my green house a few weeks ago. I only put it over the top and sides, but not the ends. It really does seem to work well. I tacked it down with firing strips. Next winter I plan to cover the ends.

What are your thoughts about leaving it on over the summer as long as I open the vents, etc. I know that it would block a low percentage of the sun which would not be a problem in the summer. I think that would let me purchase a lighter shade cloth to cut down some of the sun's rays.

Do you plan on keeping plants in your Gh all summer Muscadines? The pool cover is an insulator....so it will keep heat in the GH at a time when you want to cool things. It will also reduce the life of the cover to have it permantly installed on the GH. My solar pool cover lasted about ten years but that was when it was installed on my GH for only the winter. I took it off, rolled it up and stored it every spring. And your sunlight is much stronger than ours, here in SW Ontario, Canada.

After ten years of use, a lot of the "bubbles" on the cover had broken, there were some tears and worn spots.

I will take my pool cover off when spring finally hits and store it away until next fall. The the biggest problem I will have is keeping the GH cool.

After looking at my situation I decided to just keep my pool cover on my green house all Summer. Here is why: The Green house temp was 120+ even with both exhaust fans going. Nothing can grow at that temp. I did figure out a way to role up one side of my green house to help cool it next summer. Plus I am thinking of adding a mist system to help cool it down.

When it comes to Winter, I just purchase a pool cover that is 14x28 which is enough to cover both ends of the green house which was not covered last Winter.

Since the Winters here in Ga. are mostly cloudy I will add some supplemental lighting so that the plants can grow in the winter. There are some HIGH Lumen CFL on the market at this time.

Any suggestions would be greatly appreciated.

Hans

So pool cover on the inside of the roof or on the outside? Has anyone put a pool cover on the inside floor? If you get the harbor freight 6x8 what size of pool cover should i get to cover the whole thing? How long has your pool cover lasted? Did you get clear and what mil size? Also where did you get it and what was the price of your pool cover?