Since the insulating comes from the dead air space the difference between bubble or diamond would be small.

I have a 14mm Magni-Clear bubble cover and it is a quality cover works very well.

Is there anyone out there who is using the pool blankets for a winter cover? I just put a 14mil magna clear over my greenhouse but have a few questions. Do you find that you need to continue to vent the gh in the winter months? Should I cut holes for the exhaust fan? I have fans blowing inside and grow orchids so am in and out all the time. Any suggestions would be appreciated. mojo

I cover mine with a pool cover and also put rigid styrofoam insulation pieces over the fan and intakes and plastic sheeting on the glass door. The roof vents open but they are still covered by the pool cover. Some people disconnect them. I haven't had any problems after three winters of doing this. Inside fans run 24/7.

Do the pool covers have some sort of grommets that can be attached to with bungee cords? If not how do you attach/hold them to tie down?

rootdigging:

Pool covers don't come with grommets that I know of, so if you want a total wrap, you need to order one large enough to allow you to wrap your GH like a package, then tie it down.

If you have your GH set on a base into which you can install screw eyes, you can use bungees to hold the cover, or use rope over the top and especially around the perimiter, where you most need to prevent cold air from getting in. Soft, thick woven nylon rope or flat nylon strapping connected to short bungees both work well for the purpose.

You want to get it snug, yet leave just a wee bit of give, and the bungees provide that, along with handy hooks to connect to the screw eyes.

My pool cover is a 12 G. Diamond Clear now going into it's third winter and is still in perfect condition, abet not as clean as new. We fiddled with lengths of rope the first winter, to get them just the right length to throw over the GH in an X pattern, but once we did, we just tied the ends into loops and connected them to short bungees.

The rope or strapping will last many seasons, but as the bungees lose elasticity by being held stretched and from continual exposure to weather, they are cheap to replace.

Once you get your pool cover cut to fit just right, including a cut out for the door, it will go up pretty quickly the next season. Having screw eyes or some other means of connecting the bungees permanently installed in the base helps speed the process as well, and the same screw eyes can serve to hold a sunshade in place in summer.

I too have my GH intake vents, exhaust fan and roof vents tightly sealed for winter, but even with the thermostat keeping the heater on track, there are some clear sunny days in winter when I feel the need to cool the GH down a bit, so I just prop the door open until the excess heat has escaped.

But that's for a heated GH that must maintain 70 - 72 deg. in sub-0 temps that can hang on for days. You may not need such complete coverage in your area. It all depends on the interior temps you want/need to maintain over the course of your milder winter.

My foundation is 6x6's. The cover goes to the ground on the sides and about a foot or so over the front and back so it doesn't interfere with the door. We staple it to the foundation. On the front and back we use tarp clips, rope and screw eyes. To keep the clips on we fold the edge of the cover over a little stick before attaching the clip. Keeps it from sliding off.

Thanks for the replies. I have noticed that the humidity has really spiked since I put on the pool cover. I am growing orchids and the humidity stays between 70 and 90 percent which may become a problem if it stays that way. I have every thing closed up tight. I do have a window on the door which I can open if the weather isn't too cold, so I can dry it out a little. As far as keeping the cover attached, I have used tarp clips as well but didn't think of the idea with the stick. I also used rope back and forth over the top and ends. I am just praying we don't have a monster wind. I am hoping this will work and cut down on my power usage without causing too many other problems. Rhanks again, mojo