\ May 1976 RAIN Page 13 ·Winter Tomatoes,·Anyone? Some good friends just down the road, Bill and Marsha Mackie of SUN Experim·ental Farms, have finished their solar aquaculture greenhouse. Th'e story tells most of it:.Bill used to teach in and was the Energy Center at the Linfield Research Institute (Linfield <;allege) wh'en we first met . .. back in B. C. ... before the energy crisis. They want to expand to some outside pools this coming summer,and begin experimenting with algae and its uses, as well as other pond life-forms. After • the story, there's a list ofgreenhouse reso,urce people across the nation. Ifyou write them, please send a SASE. (LJ) Inside the Mackie solar aquacu,lture greenhouse. Note water, drum wall heat storage on left. We started our greenhouse in the spring of 1975, worked on it slowly throughout the summer and had it completed enough to begin using in the fall. Although there are'always modifications and improvements to be made, we are satisfied with its performance through the winter and are now convinced that Oregon's sun is strong enough to provide all the heat and light a greenhouse needs. . Our greenhous·e is an 11' x 16' free-stan,ding structure, partially sunk into the ground for insulati~n.. It ·has glazing only on the south side. A fish tank extends the length of the north wall and above it are eight 55-gallon drums painted flat black .. _a,nd filled with water. Both the drums and the fish tank are used for heat storage. Digging the hole proved to be the single most time-consuming job in the entire.con_struction process. We dug it by hand, slightly larger than the finished greenhouse, about 14' x 18' x 2-1/2 \ The dirt dug from ~he hole was bermed against the north wall of finished structure for added insulation. • A concrete foundation was poured the perimeter of the gr.eenhduse and as a ,continuous ~lab under the fish tank. Then , we began laying a 40" high concrete block wall all the way around and'also 4' in from the north side to form the fish tank. Drain tiles were laid on the un-concreted earth and we poured several inches,of gravel for a floor. The drainage ditch empties into our garden, so whatever water we pour out onto the floor, including the rich algae bloom we siphon out of the fish tank, goes to water and nourish our garden. .One of the things we didn't do which we wou'ld do a second time is insulate between the fish tank and the earth. Hopefully t~is would elevate the water temperature to keep•the greenhouse warmer during the winter, but primarily to lengthen the season for raising warm-water fish. As it is, we are adding a solar collector to boost the water temperature of the fish tank. The north, east and west walls are regular framed-in walls with 3-1/2'' of fiberglass insulation. We felt the extra, insulated wall area was worth the decrease in solar radiation'. Painting the greenhouse interior white would probably increase the solar tadiation falling on the plants and,.at least partially com-. pensate for tl).e light loss. The south wall is a double layer of 30 mil Kalwall fiberglass tilted at an ~ngle of 45,,'. The space between the two layers, the width of a 2x4, holds an insulative batt for extra protection on cold.nights. It was not until February that we added the second layer of glazing, so the greenhouse went through the cold part of the winter without the benefit of its second layer of fiberglass or its insulating batt. A few nights the inside temperature • dropped to 45°, colder than you really would like a gr~enhouse. Daytime temperatures, however, were generally up around 60° or 65°. Despite the cool nights, we lost no plants and..) 1re optimistic about our greenhouse's ability to hold heat with its second layer of glazing and its insulative batts in place. • . At the present'·time we have about two dozen largemouth bass in the fish tank. We're anxious for the tank temperature to rise enough so we can put .a pair of tilapia in. Hopefully, with the aid of a solar collector, we'll be able to extend the warm-water seasqn long enough to harve~t two or three crops of tilapia froll,1 our tank this summer. , For a copy of the greenhouse plll;ns, send $2,and a stamped, self-addressed envelope to SUN Experimental Farms, 835 Fleishauer Lane, McMinnville, OR 97128. Or if you just want to·write, we're ~lways interested in what others are doing. \
RkJQdWJsaXNoZXIy NTc4NTAz