An Easy DIY Dehumidifier

Don't worry, there will be pictures (I'll edit the OP so that it looks professional).

I live in a coastal area in California that can often suffer from excess humidity. In the summer time this can be managed indoors with the AC unit used to cool the area. During the winter months dealing with the humidity can be a bit of a chore and a drag. Flowering during the winter time compounds the issues as molds are more prevalent in the air making the artificial lowering of the humidity to prevent bud rot as an essential process.

Compressed units make a ton of noise, and use an excess of electricity. New technology uses ions to extract the water though these units still require moving parts. As a result the life span of these moderately inexpensive devices is unacceptably short. Still, some of these devices contain an addition. UV light is added to kill the bacteria and mold that pass through the system which could side-step the problems found in higher humidity environments.

Passive systems like DampRid provide an inexpensive alternative to quietly remove moisture from small areas. These systems are going to be slower, but as a result of their simplicity we can build several variations using the important chemical compound Calcium Chloride.

Calcium Chloride is a very easy to come by salt. Known as "Ice Melt" you can purchase it in 50lbs bags. Also, pool supply stores will sell it as a water calcium hardener. "The anhydrous salt is also widely used as a desiccant, where it will adsorb so much water that it will eventually dissolve in its own crystal lattice water." -wikipedia

And here is the process.

You'll need to design a two tier system. You can use things like thin/cheap plastic storage boxes, or 2 liter bottles with the tops cut off and stacked, or ziplock bags and little duct taped ingenuity. Regardless of how you choose to do this step you're going to need a top container that will drip into the lower container.

The upper tier will contain the calcium chloride crystals. It will be open air and, if you can manage it, blowing air over it will increase uptake. You will need to place many pin sized holes in the bottom of the upper tier; this allows the crystals to dissolve and drip into the lower tier.

The lower tier can be empty at the start and it will begin to fill with the dissolved solution. I think a better option than a drip reservoir is to use kitty litter to catch the moisture and lock it up.

Place the system wherever you'd like to in the room, but I would suggest it is close to your intake air. This gives the Calcium Chloride the first shot at the moisture.

When the thing is full of water you simply empty your lower tier, replace your Calcium Chloride in the upper tier, and that's it, that simple.

Now what can you expect from something like this? Well, that all depends on the size of your room, the ingenious of your personal design, your RH (it works better at 50+ humidity), and yadda yadda. So, as a general rule here, it will constantly keep your RH about 10 points lower than the intake. So from 70 to 60, or 60 to 50. Around 40 though it get's tricky, and it won't reduce the humidity much below 30% unless you have several "diy dehumidifiers" in the room.

So, $6 on 4 lbs Calcium Chloride pool hardener and another $6 on a bag of kitty litter, couple of two liters, or ziplocks with some duct tape and you're set. I hope this helps you guys out and when I build another one we'll get some pictures up.