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.

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.

Brrrrrrrrr!

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.

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. 

What Is and What Will Be In My Greenhouse

Beginning in April of 2011 I began to make plans to turn my existing greenhouse into an aquaponics garden.  At this point, late November of 2011 I have accomplished an initial harvest in the grow bins pictured on the lower part of the graphic above.  I am still harvesting tomatoes from the three bins pictured on the lower right and herbs including beet greens, mint, parsley and dill from the three bins pictured on the lower left.  I have yet to experience a success at growing fish.  State regulation of fish suitable for eating are a major block to stocking my pond with trout or other edible fish and since I have decided that koi will best suit, and I don't want to waste the lives of anymore fish until I have my other items in place, I have sustained my plants with occasional supplements of chelated iron and other minerals and soluble plant food. 
I am now ready to set up the next two sections of the growing area.  These include hanging tubes for vine plants along the north wall of the green house and trays for lettuces and similar plants along the center.  The growing trays are made of rain gutter with an electrical cable along the bottom to heat the water as it flows past the roots.  The lettuce will be planted in coco fiber contained in plastic cups. 

Several Ways to Harvest Sunlight

I have essentially finished my 'winter coop' which is adjacent to my greenhouse.  The picture above may require some explanation.  Under the corrugated polycarbonate sheet that constitutes the roof of my small chicken coop are two separate systems for harvesting solar power.  On the left is a solar panel with the battery pack above it.  This gathers electrical energy to power the 75 watt incandescent bulb that turns on for several hours in early morning with a timer, adding necessary light and heat.  On the right is a black painted panel on which I've placed 36 cheap water bottles.  During the day the black panel heats up the water in the bottles which is stored as thermal energy and released gradually as night falls. 

It's Getting Cold

We've had a couple of nights when the temperature fell below freezing but I've found some ways to add enough heat to the green house to avoid death of my tomatoes.  The first night I found out rather late in the day that it would freeze.  I quickly set up a little charcoal grill that has a domed cover.  We lit it and the following morning I found that most of the briquettes had been consumed, but not all.  Although I plan to eventually install the necessary heat and smoke dispersion to my chimenea, for now I found a room sized convection heater for less than $40 at Home Depot plus a 'Frost King' regulator plug in that will start the heater when the temperature drops to 35 degrees and stop the heater when the temperature raises to 45 degrees.  This will save on electricity costs while keeping the killing frosts at bay.  It is 'hard freeze' that kills plants. 
I also purchased four workshop 2 tube florescent light fixtures and a box of daylight (6500 kelvin) bulbs to add an additional amount of light and some heat directly over the grow bins.
I plan to plant lettuce, peas and spinach in rain gutter trays that are heated with a warming cable meant for seedling trays.  These are intended to be like the display at Green Sky where the water trickles down the gutter and discharges into the fish tank.  After looking at the price of 'rock wool' growing bricks and other alternatives I am using coco fiber in my grow cups.  This came about when I found a super sale on some hanging baskets furnished with coco fiber.
Meanwhile I'm making a mad dash to finish up my 'winter coop' which will use black painted tubes filled with water to gather heat during the day as well as a solar panel to run a fan and light.  It will be interesting to see how I get through the impending winter.