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[happyconcacti]

Hello All,

Background
Recently I built two insulated chambers for starting seeds and propagating cuttings. I mainly did this because Summer was ending and so were the warm temperatures (I live in USDA zone 5). Also, I starting T. iboga from seed and kept reading maintaining +86F is essential. Keeping my house at a cozy 80 F (27C) would be incredibly costly and near impossible, its an old house. Plus, the room I'm "allowed" ;-) to take over with plants is by far the coldest room in the house. Seedling mats alone are not enough to keep high temps.

The chambers are working well by maintaining high humidity and temperatures of 84F +- 3F.

Overview
Essentially, I built a foam box. The box has a viewing window on one side. The top of the box acts as a lid to the chamber and has two dome light fixtures installed in it. The lights are plugged into an analog timer so the plants get 12 hours on, 12 hours off automatically. Inside the foam box holds a glass fish tank. In the fish tank is a layer of expanded clay with a seedling heating mat on top. The clay provides moisture. The heating mat is plugged into a thermostat that has a probe inside the chamber. It keeps the temperature regulated.

IMPORTANT: I designed the box so there is a 1" gap between the inside of the insulation and the outside of the fish tank (see the first picture below). I did this because air, when confined to a small space, acts as an excellent insulator. If you put insulation up against the glass of the fish tank, you're losing out on this insulating feature of air. If you put the insulation too far from the fish tank, convection currents can occur, diminishing the effects of air as an insulator.

Materials for One Chamber:
2" wood screws        x16
Tape (packaging, duct, or other durable tape)
20"x10"x12" aquarium (pets mart ~$20)
8" Dome light fixtures (hope depot ~$9)    x2
Seedling Heating Mat (large size--HydroFarm ~$25 ebay)
Heating Mat Thermostat (HydroFarm-not pictured ~$33 ebay)
Analog Outlet Timer (Home Depot ~$10 -not pictured)
8' x 2' x 1" R5 insulation foam (home depot ~$15)
12" x 36" glass (home depot ~$15)
mylar emergency blanket (~$3, outdoor sporting store)

Tools:
Glass scorer
Sharpie
Right Angle Square
Measuring Tape
Screw Driver
Sharp Knife or Razor

Cut the foam to the following sizes:
14.25" x 24"  (x2--top and bottom panels)
13"x 12.25" (x2 -- small side panels)
13" x 24"     (x2 -- large side panels)

Its really important that the edges of the foam panels are square. Please use a squaring tool when drawing out your cuts.

1) Assembly of Box
Place the bottom panel on the ground
Place a large side panel and small panel vertically on top (so the 13" dimension is vertical)
Carefully screw a few wood screws into each edge to hold this shape
Assemble the other panels (except the top) in this fashion
Tape the Edges to Seal Cracks

2) Making the Lid
Place the two light fixtures on the lid and trace around them with a sharpie.
When you cut these out, cut an 1/8" to the inside of the circle you traced. You will "press-fit" the light fixtures in so they are gripped by the lid.

3) Cutting Glass for Fish Tank Lid & Viewing Panel
A) Making a Fish Tank Lid. The cheap fish tank from Pets Mart did not come with a lid. I used sheet of glass, mentioned in the materials to make a lid for the fish tank. I cut the lid to 20.25" x 10.25" so it sticks over the edge of the fish tank. Also cut a 1.5" corner off of one corner to run electrical cords into the tank.

B) Making a viewing panel. with the remains of the sheet of glass, cut that piece in half so you have (2) 6.25"x14" pieces of glass. Take one of these glass panels and place it on a long side of the foam box. Trace it. Cut 1/4" inside the traced rectangle. Tape one glass panel on the outside of the box and one on the inside for a double-paned viewing window.

4) Cut Mylar out to cover Inside
The mylar will help keep heat in and also reflect the light off the walls to the plants.

Discussion
I'm not sure whether this is the cheapest way to go about an insulated chamber. It works incredibly well though. Ambient air temperatures have reached 58F while the chambers have maintained 84F inside with the lights off. Under the aforementioned conditions, the heating mat came on about once an hour for about 10 min. Otherwise, the heating mat comes on sporadically.

The biggest problem with the design is airflow. I open the chambers a few times a day to circulate new air. Fungus/mold has been somewhat of a problem. Also, a few Mimosa hostilis seedlings seemed pretty weak from not getting wind-blown strengthening.

Possible Modifications for Future Iterations
--Simulate wind on timer -- to help stiffen seedlings & reduce fungus/mold
--Buy large foam cooler instead of making one ;-)
--Lid of box & lid of aquarium on hinges -- easier to open
--Make blank side of foam insulation faces out -- hide all the advertising crap printed on the foam underneath the mylar

6 Likes Mandrake, New Wisdom, Seed Collector, onion, AcaciaAve and 1 more people like this.

[happyconcacti]

The rest of the pics:

4 Likes Mandrake, Seed Collector, fairdinkumseeds and AcaciaAve like this.

[New Wisdom]

I have a suggestion to improve upon this model. Get some of that shiny white poster board and put a layer of it on the inside of the insulation to reflect the light better.  I think it'd help create more light in there.

EDIT: I didn't see the mylar step. My bad. Lol, That'll work better than poster board.

Awesome job on this by the way. This is kind of like mine but I didn't put any insulation like that in it. 

Thanks for sharing!
New Wisdom

1 Like happyconcacti likes this.

[PermieGing]

So what would be a decent way to simulate wind in the chamber, without the temp decreasing??

I think i may have to build one of these!!

[Sunshine]

So what would be a decent way to simulate wind in the chamber, without the temp decreasing??

Any wind will decrease temperature. It's called windchill bro. lol :p

But...a computer fan Jerry rigged with a 9-volt or something similar might work...I'm just  spit balling. You'd have to check the resistance or whatever on the fan...

[Khaedin]

So what would be a decent way to simulate wind in the chamber, without the temp decreasing??

Any wind will decrease temperature. It's called windchill bro. lol :p

But...a computer fan Jerry rigged with a 9-volt or something similar might work...I'm just  spit balling. You'd have to check the resistance or whatever on the fan...

You can wire computer fans to 5V cell phone chargers. Its really simple. Depending on the size of the fan, you can wire more than one to the same plug. There are tons of videos and tutorials all over the web for it.

[dEEcor]

GrEaT project 

If you place the lamps entirely in the box their heat will be already adequate depending on their kind, amount and power.

I´ve been surfing the web a lot for information about plant light and it seems to me that there are lately more people convinced of using white instead of reflective cladding. It makes sense because white is every colour well mixed and spread if you look at it when every colour is present. Reflective material focusses the light in a way that we can (almost) see a copy of the real surrounding depending on different variables. So plain white will reflect whatever wavelenths more homogenous.

In Germany you can find an old aquarium for free easily. Maybe it is the case in your country too. Same thing with an old cupboard, which insulates already.

Like Khaedin wrote; take an old power adapter and simply connect the output wires with your fan(s). If you got too much voltage output then take more fans and connect them serially so the voltage and operating speed halves each time.

Sunshine wrote that you´ll loose temperature due to the airflow. I think it´s ok, if you let them run slowly. You can also make one flow direction passive. Alternatively you can let Oxygen flow entirely passive through layers of Tyvek fabric.

A (computer) programmable plugbar can be very convenient for all sorts of experiments.

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