Here is what it costs to build a cold tank

[Jeff9]

Hello,

I have researched and asked alot for months on end about building a cost effective and efficient cold tank to grow species from Papua New Guinea.
I will outline in this thread what it has roughly cost me so far to build the tank.

Cooling methods
There are various ways to cool your tank, only a few are cost effective and viable.
A few methods are:

1. Phase change cooling, the same technology used in refridgerators.
2. Thermoelectric cooling, used for various small cooling appliances and completely useless for what we are trying to do here, they lack the power.
3. Basement, if you have one, this is the best way to do it.

You could convert a refridgerator, freezer, wine fridge, or build/buy a phase change unit to cool your tank, but it is expensive to buy and operate so i would advise against it.

The thermoelectric units / peltier chips, undoubtedly lack the power to cool anything bigger than a lunch box.

The best way to do it would be to use a basement, or draw air from outside during the night. I went with the latter, you can read about it more on the blog of Orchidkarma.

I am using a lucky reptile thermo control 2 thermostat to manage the temperatures.


Lighting

Artificial lighting is the most reliable, and it gives you full control on how much light you give to your plants.

You could go with LED's if you want to keep it cooler during the day, but in my case the Oxyglossum species im growing only require cool conditions at night.

I am using two 24 watt lights, i would've gone with something more powerful if i were buying it now. Probably dimmable also.

Water and humidity

I am growing Oxyglossums, and water quality is absolute key. I am currently using demineralised water but i will be switching to R/O in a few weeks.
I use Akerne orchids' rain mix which is a MSU-type fertiliser.

I will be using a Lucky reptile super fog, i will keep my humidity at 70-80% during the day and 100% at night.
I will water very sparsely by hand, since i will be growing most of the Oxyglossums potted, they don't like to stay soggy or wet. I keep them damp with high humidity and they thrive.

Medium

I am using a homemade mixture of charcoal, sphagnum and perlite/american white sponge rock 4-5mm.

I fill the pots 2/3 with charcoal and perlite mix, the top 1/3 layer is AA+ grade sphagnum, charcoal and perlite. I try to use as little as possible organic matter to avoid repotting for as long as possible and to avoid breaking down medium.


Costs so far
Cooling components:
Ventilation fan: €20
Flexible tubing: €10
Thermocontrol Pro 2: €56

Tank, 50x60x70 finished with hardwood and sliding profiles €150

Misc:
Super fog: €84
Lights: €96
Commercial seedling trays, charcoal, sphag, perlite, MSU type fertiliser, misc materials: €100
Misc products/items bought at local hardware stores to assemble, build etc: €100

Total: €616

I estimate the operating costs will be about €70-100 a year.

During the day a small 12v fan will run along with the Superfog keeping the temperatures around 20-25C at 70-80% humidity.

During the night the large ventilation fan will be drawing outside air keeping the temperatures at 12-13C while Superfog keeps it 90-100% humidity.

In summer i will use an airconditioning unit to cool at night.

Will update after more progress

[mremensnyder]

Thank you for the informative post Jeff. I had tried thermoelectric cooling on and off for years in a terrarium, with very limited success. At one point, I was using a large Coleman thermoelectric cooler, with a lighted fish tank on top (bottom of fish-tank removed). It would cool properly for a few weeks, then barely cool at all for a few more months, before finally burning out. Ultimately, I have given up on this as a feasible colling method. Right now, I am going low-tech, using three frozen cold packs which I place in the tank each night after the light turns off. This drops the temp about 10 degrees to 60-62 F for a few hours. I may eventually try to get an old wine-fridge or the like, when finances permit. If I lived further north in a more temperate climate, I would definitely utilize a basement and circulate cool night air. One question, do they currently make any LED lights strong enough to grow and bloom low/medium light orchids like Lepanthes, etc.?

[Tindomul]

Thanks for the breakdown. This always gets me thinking how great it would be to grow cool loving species in my living room (I have no basement).

[Mercaptan]

Thank you for this post, it makes me realize growing cold species wasn't a crazy dream at all without a greenhouse.

But, certainly the most important, where do you found oxyglossa in Europe ?

[Jeff9]

It's certainly very hard still, and expensive.

You will have the best results if you use a basement or have a greenhouse thats deep in the ground.

I've seen people use fridges and wine coolers of the sorts, but firstly regulating them with a thermostat would most likely damage them. Plus it's pretty hideous.
I'm looking more at a permanent setup.

Even with an airconditioner, you will have to get one with a mechanical on/off button, not a digitally controlled one. I haven't found one yet, and pretty much gave up on it!
Not to mention running mobile A/C units is like throwing away money.

If you have a basement, use it, and setup something like a evaporative cooler or a aquarium cooler to cool it down further.

Oxyglossums in Europe is easy, if you pm me i can tell you loads of places where you can get them.

Unfortunately alot of the harder to find ones like putnamii and dekockii are impossible to get pretty much.