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Friday, December 30, 2011

Root Zone Heating and Insulation of Greenhouse

When I intended to use my greenhouse mainly for storage I installed a double layer floor over the native dirt instead of using gravel.  I wanted a surface I could easily clean.  The first layer consists of 3/4" thick mats of recycled tire rubber which had been used as an athletic floor in a gym.  Over this I placed an indoor/outdoor carpet that extends from wall to wall.  This flooring has proven resilient to flooding.  I recently learned that insulating the floor of a greenhouse is a good idea since the earth itself can suck a lot of heat energy out of the greenhouse.  The thick black rubber floor makes a good insulating layer.  Years ago I purchased a large amount of mylar faced bubble insulation which was on sale with the intent of using it in a projected construction project that never was realized.  I have been able to use this material in the lower wall areas of the greenhouse where transparency is of no value.  Because it has both insulating properties and is reflective, I plan to use it under my nutrient film trays to retain the heat provided by a 40 foot seedling heating wire.  Adding and retaining heat are my chief concerns at this time of year.

Thursday, December 29, 2011

Crop Choice and Water Temperature

The summer and autumn seasons of my greenhouse aquaponics were a limited success.  I grew edible crops and found ways to combat excessive heat gain in the greenhouse with materials I had on hand.  Winter has presented a more difficult challenge.
My tomato plants were killed by the low temperatures of early December, however the herbs I planted in the other half of my bins have survived the cold and remain green.  The attempt to heat the greenhouse with a chimenea turned out to be destructive of the insulation on the ceiling, but the insulation which has deformed and withered probably kept the polycarbonate roof from melting.  I plan to do more work on the use of other methods such as a rocket mass heater, but at this time I will continue to use a propane heater to moderate the air temperature.
We have now focused on keeping the water system stable and preventing freezing.  We have a titanium fish tank heater on order and we have wrapped the pipes in the system with heat tape and added tube insulation.  Freezing in the pipes creates imbalance in the dynamic flow of the bell siphon system.  It also threatens structural damage to the tank and pipes  if the water freezes hard and expands.
Herbs and green vegetables such as spinach, mint, beet greens and cabbage resist cold air temperatures and continue to produce in the winter.
I can start crops like strawberries and tomatoes earlier in the greenhouse and keep them longer as the weather cools, but it is evident that I should switch them out for more hardy crops before sustained sets in.

Saturday, December 24, 2011


I went to Hawaii earlier this month and while I enjoyed the tropics we had a cold snap in Utah.  I had set up a heater in my greenhouse but it wasn't handling the really cold temperatures.  On the other hand, one of my chickens managed to get out of the coop one night and froze to death.  My son moved the heater from the greenhouse to the chicken coop and suddenly the two chickens left are laying eggs and doing fairly well.  He started using the chimenea to provide heat for the greenhouse but there are laws in Utah County that forbid wood burning on certain winter days when the atmosphere is trapped in the valley, creating an inversion and smog.  We went shopping for a propane heater and it seems to be doing a better job than the electric heater.

Thursday, December 1, 2011

There are Fish!

I tried putting 20 goldfish in my fish tank several months ago and as far as I could see at the time, there were no survivors.  Yesterday while redoing some plumbing on the fish tank I discovered two healthy gold fish.  I haven't really fed them, but there is algae growing in the tank and I guess they were doing fine as cold water vegetarians.  Someone at the aquaponics association meeting told me that it might be disease and not water quality that killed the initial batch of fish.  Apparently they were right.  Go figure.