Now it's time to start making this thing look like a greenhouse. The ends get covered first. I am using two layers of a poly film made by a company named Klerk's. I chose their 'KL-50 Clear' because it will filter UV light up to 360 nanometers in wavelength. We should all be aware that our target range for coral lighting is the 400-700 nm range (light that leans towards the blue end of the spectrum). Through some research, I found that UV-C (light in the 200-280 nm), while very destructive to life, is naturally filtered out by the earth's atmosphere and isn't significantly present on this planet but may be found in some high energy applications such as the light emitted from an arc welder or some UV sterilizer bulbs. UV-B (280-320 nm) is also destructive to tissue. UV-B is the light that gives us a sunburn. UV-A (320-400 nm) is what's needed to maintain the fluorescing pigments of corals, at least towards the upper wavelengths of that range. There were some studies which suggested that UV-A from 310-350 nm may be at least partly responsible for some bleaching events. Many corals can produce compounds known as microsporine amino acids (thick clear-ish or opaque mucous coat) which is basically a sunscreen that will absorb light in the 310-360 nm range. These compounds are absorptive pigments only and are not reflective so they do not contribute to a corals' coloration. I found that the reflective or fluorescing pigments, in general, were maintained with light around the 390 nm wavelength so this poly covering was almost perfect in that regard. By filtering out light less than 360 nm, most of the corals wont need to spend energy producing a "sunscreen" but will still have the wavelengths they need for coloration. The corals that need higher wavelengths can have screens placed above their tanks to provide the correct amount of light. Anyway, here goes the first layer of the greenhouse glazing on the north end.
Layer two and both layers trimmed.
The south end with both layers on. The small black circle seen on the left sides in the above and below pictures is an 1 1/2" flexible hose which will allow the air to pass from the main portion of the covering to both end sections. Later, the two layers of plastic will be inflated by a small blower to act as an insulating layer.
Just foolin' around here and the picture doesn't do the brightness of the sun justice. Pictures just don't have that "have to squint" effect like the real thing but this is through both layers of plastic.
At this point, I'm a little upset because when I went to unroll the plastic for the main part of the greenhouse, it was the wrong plastic. It had an additive that is intended to filter infrared light and also diffuses the light. (Even with that one mistake, I must say that the folks at Atlas Greenhouse are some of the nicest, most polite people on the planet. I called seven different greenhouse suppliers during my research phase. There were some that were less expensive but when I called Atlas, everybody there was so bright, cheery and very knowledgeable about their products. They simply won me over with kindness). I have never been called 'sir' so many times in one conversation. When I called my salesman about the plastic not being what I ordered, he took full responsibility, sent the correct roll that same day and included a prepaid return label. It all worked out ok anyway since there was plenty to do while the new roll of plastic was being shipped, like install the door and shutters. Isn't a locking door on a greenhouse a little senseless?
The correct roll of plastic arrived and wouldn't you know it, the wind was blowing with gusts up to 25 mph. Do you think that would stop me? Do you think I would wait for another day? No way, just had to get it done today!! Imagine a 155 pound man holding onto a sail that is 45 feet long by 35 feet wide. To quote the now famous words of one of our founders, WEEEEEEEEEEEEEEEEEEEEEEEE.
Well, it didn't beat me but I had to finish up by moonlight. At least the first layer is all tacked into place.
By daylight with both layers on. I have had to re-stretch the plastic twice after the initial installation because it was a little cool when I put it on. As the weather warmed back up, the plastic relaxes, expands and becomes a little loose. It's amazing how much skin that soft plastic can abrade from a person's knuckles.