Backyard Aquaponics
A place to discuss aquaponics

I think I remember something about catfish in farm ponds liking to spawn in hollow logs or empty sunken containers. Vague bits of info float in my head. Comments that catfish often didn't spawn in farm ponds because folks didn't put appropriate spawning shelters in for them. See how good my memory is.

Boy, your air temp comes up nicely. Passive solar is so cool! Now you just need to find a way to hang on to the temperature gain. Maybe thermostatically triggered insulated curtains? Forgive me if you have already thought of that one.

My method of storing heat from sunny days is massive concrete and 4000 gallons of water. The glazing is only 220 sq ft on a slant that is correct for my latitude in the winter 60 degrees. The glazing is twin wall 8mm Lexan (polycarbonate) with R=2 (that is my big heat loss) and curtains would really help. I have yet to think of how to make automated curtains practical without handling them twice a day. So I am going to wait and see what will happen without them. I have used cases of caulk and I never feel a draft. I have to balance between being so air tight that fungus kills all my plants and trapping heat.

Temp update: 3pm 74F in greenhouse and 24F outside. Last nite o/s lo was 15F and inside lo was 49.8F. As energy costs rise, we may move into the greenhouse.

One method I have seen of superinsulation overnight that is more automagic, and therefore computer controlled, is to put a single pane of glazing inside (or outside) your current glazing material, pipe to the bottom of the airspace with 2" pipe, and at the top, put some screen on (to allow air to flow). Then get some styrofoam beads and blow them in from a bin. When you want to start getting the light, reverse the flow into the bin with a wet/dry vaccuum type setup. In reality, it may be better to fill from the top, suck from the bottom, and just recirculate the air through the vaccuum.

Just some food for thought....

Doug, I saw this method in one of the solar greenhouse books I read before designing mine. They were using a commercially available unit.

DIY version...hmmmm....interesting!

Doug,

I wouldn't get too excited about excluding every skerrick of external air. The fact is that your greenhouse will need ventilation or you will experience problems with fungal spores.

Given the high tech nature of your system, have you considered using High Pressure Sodium or Metal Halide lights to boost growth in your plants?

As you're probably aware, these lights generate a lot of waste heat which is normally an issue for growers (particularly in warmer climes) but, for you, it's different. Your set up needs warmth so the efficiency of these lights is vastly improved because you are using both the light and the heat.

Gary

That's a good point, and one I've contemplated many times. I have a few questions about using HPS in extreme conditions:
1. Do you feel it's better to put them on a timer, or run them continually?
2. If on a timer, would extreme temperature differences lower the lifetime of the bulb?
3. If not on a timer, is there an efficient way to move/store the excess heat (hopefully for later retrieval)?
4. Do you run the risk of bulb explosions if started from below freezing temps?
5. Does anyone have a list of BTU rates for 100w-400w HPS?

Gary, I am trying for lowest possible purchased energy use. If I must use lights in the winter due to short days, my first try will be with the new wide spectrum florescents That claim to be 4x more energy efficient than HPS for same lumens. I have been using one of these from Home Depot for my barn light. I am impressed with the light spectrum. It only cost $59 as a total unit.

bhsx, you can count 98% of energy to HPS as heat output. A 1000 watt gives you about 980 watts of heat. Each watt is about 3 btu. I would recommend a timer. On from 4pm to 10pm will greatly augment your daylight. I do not know the extreme temperature affects on them.

Thanks, wow, 98%? I wouldn't have thought anywhere near that high!
If memory serves you're going to grow leafies, right? I think even the wide-spectrum flos need to be replaced with HPS for plants while fruiting (could be wrong, of course).

I've only got leaf out of flouro. HPS certainly has what it takes for flower but yeah, lot of heat off them. Friend and I designed a tank on a metal plate with an enclosed HPS under it. Glass bottom. And an AP cabinet under that. The heat transfer went into the metal and helped keep his aquarium heated.

HPS are far more economic on light rails. Worth googling if you want to use them.

bhsx, sorry, the HPS is 10% light & 90% heat. The link below gives some useful information. Some HPS are used for outdoor lighting. I had one on my barn before the flourescent. Therefore, I know they handle very low temperatures well. At least the ones meant to be used outside. Note in the below link the table of lumens per watt.

http://www.darksky.org/resources/inform ... is052.html

Great link Doug, exactly what I needed.
Also, good to know that you had one outside, as you get even colder than we do on average.

[font=Times New Roman] [/font] Been working on my heat exchanger. Just finished it The first day I had water in it to test for leaks, it was 21F outside & 68F inside and very sunny. The exchanger in the sun was too hot to touch. I checked the water temp with a thermometer and it read 130F. That was with the pump off and the water not circulating. With circulation the water would stay cool and bring the solar radiant heat right into the tank. It really looks good. I intend to automate it and only pump when the temp differential gets to some level. Then I will run the pump for a few minutes and stop. This is just to reduce energy use on pumping. My next post will be the pictures and system description.

The heat exchanger carries antifreeze to handle Michigan winters. The exchanger in the sun is at the top of my glazing inside the greenhouse. It is made of six 10 ft lengths of 0.5 inch copper tubing. This is connected thru a pump, view port, expansion chamber, and air bleeder to the exchanger in the fish tank. The exchanger in the fish tank is two 10ft lengths of 3/4 inch copper tubing connected with clear flex tube. Why ther different sizes of copper tubing? Because it was what I had on hand and the prices now are outrageous

The copper pipe you can see in the tank will be covered with metal paint before the water goes in. I had two leaks and I left paint off the copper joint in case I need to re-sweat them. Once the system proves leak proof, then another layer of paint goes on the joints. Happy with the exchanger. Also, put a computer controlled reversable 12 volt motor on my 11 front knee wall vents. The motor could not lift that much weight. So I went to E-bay an bought a 10:1 gear reducer for $80US. Now it works perfectly

Finally, itis time to build my grow bed (3' by 32') along the glazing
With the grow bed and the 100 gallon Rubbermaid stock tank rigged as a combined solids and biological filter, I can put water in the fish tank ( afull 18 months after the tank concrete was poured I have been very frustrated with how long it is taking to complete my aquaponic system. I had to take time to do contract work and travel and...and... Anyway, I am getting close! I know cause I can smell the fish

that looks great Doug, well done! What did you end up painting the pipes in the fish tank with?