Building a lid for Your Terrarium

There are many types of dart frog terrariums, every thing from the new Exo Terra style front opening tanks to custom built terrariums. However the most common type of terrarium is still the re-appropriated fish tank. While there are a few issues with this sort of terrarium, overall they work great for dart frogs. However, the main weak point of the fish tank are issues surrounding closing the opening at the top of the tank. This is a critical part of your dart frog terrarium, and while its not an especially decorative or “fun” part of your terrarium, it is definitely one of the most important aspects of your terrarium. In this article I will discuss some of the strategies for building a lid for your dart frog tank.

The first and most obvious function of your tanks lid is to keep your frogs in. Duh, right? But all too often the lid is the culprit in dart frog escapes, and occasionally frogs are crushed by the lid. Another function of the lid is to keep food, such as fruit flies, in the tank. Even though the fruit flies used for dart frogs cant fly, they do tend to walk straight up the sides of the tank, and will rapidly get out of your tank if the lid does not fit very tightly.

The third function of the lid of the dart frog tank is to allow the keeper to control the humidity in the tank. Dart frogs obviously require a high level of humidity in the tank, and when you are dealing with an aquarium, the lid is going to be your only area where you will be able to affect or tinker with the humidity in the tank. Many keepers use the “hood” that comes with fish tanks. This plastic hood usually has a light fixture, and features a door that opens at the front of the tank for feeding. These hoods are often to blame for frog escapes, and do not fit tightly enough to keep fruit flies in the tank. There are often gaps and cut outs at the back of the tank, which may be convenient when it comes to putting pumps or other electrical items in the tank, but again these offer paths for frogs and flies to escape the tank. With modifications, these hoods are sometimes successfully used for a dart frog terrarium, but in general the hood that comes with the tank is not a very suitable lid for your dart frog tank.

Another choice of lids is a piece of glass, or two pieces of glass cut to cover the top of the tank. This is the simplest and easiest lid to make for your tank. Glass lids are escape proof for both frogs and flies, and maintain a nice high humidity for the frogs. They are easy to obtain, as you can have a lid cut for you at a local glass shop. It’s probably best to have the lid made from ¼ inch glass, so it will be sturdy enough to withstand minor knocks and bangs. My recommendation is to have the lid cut in two pieces, with a larger section that will be your fixed piece, and a smaller section that would be your “door”. For instance, if the top of your tank is 30 inches long and 14 inches wide, you would need a 9 inch by 30 inch piece, and a 5 inch by 30 inch piece. Leave an eighth of an inch or so on each piece for wiggle room. Carefully measure the opening in the top of the tank, and make sure that you measure from the inside of the opening, where the glass would sit. When you order the glass, the shop can treat the edges one of three ways. The first is to leave it untreated, which will result in very sharp edges, which will have to be sanded or smoothed out someway or another. The second way is to have the edges “eased”, which means they will run a bit some sandpaper over the edges to knock the sharpest of the edges down. The glass will be safe to handle now. There is usually a small charge for this. The third method, which many glass shops will do without being asked, is to “finish” the edges, or polish them so that they are a bit rounded off, and no trace of the smooth cut areas are left. I’ve been surprised at how much some shops will charge for this, so inquire. I’ve also been surprised at how much variance there is in prices from one shop to another, so it wouldn’t hurt to get a quote at a couple of different shops.

While a glass lid is simple, effective and fairly easy to find, they do leave something to be desired. The main problem with glass lids is the fact that they are too good at keeping the humidity high. A glass lid will, by default, keep the air in the tank completely saturated with moisture, since there is no escape for the humidity, it simply saturates the air in the tank. Then it precipitates out as condensation. This leads to the glass being covered with condensation, and the inside of the tank, plants included, stay wet all the time. Frogs love this, but it’s possible to make them happy and make your tank look better too. The key to doing this is getting a bit of ventilation into the tank, but not too much. Since you won’t know how much ventilation will work for the tank, it would be good to be able to adjust the humidity a bit as well. So, the following paragraphs will cover some ideas for achieving this in your tank. Before we go any further though, let me get one last point in about the glass lids. If you wish, your glass shop should be willing to drill holes in the glass for you, and you can follow the designs below, but without the reinforcing u-channel. Most shops will charge you around $10 per hole, which is going to add up to $50 to $100 for these holes, making this an expensive way to go. However, if money is not a big issue, then I would just go right for this option! Lay out the design of the lid and take your plans with exact dimensions and locations for your holes to your shop.

The alternative to glass is to use ¼ inch acrylic for part or all, of your lid. If you are making a two part lid, you can stick with glass for the back portion, but use the acrylic for the front panel, where you are going to put your ventilation holes. Or you can use acrylic for both parts of the lid. Before we get too far discussing acrylic, lets cover some basics about the properties of this plastic, especially as they relate to use around the terrarium. First acrylic, and other similar plastics, is/are absorbent, and will soak up water out of the air. When one side only is exposed to high humidity, it absorbs water and begins to swell. This leads to the acrylic warping. Many a proud frog keeper has finished their dart frog tank lid out of acrylic, only to wake up the next day to find that the lid of the tank is warped and their frogs are no longer in the tank. That is the main drawback to using acrylic. However, as you probably have figured out, acrylic has some huge points in its favor, the main one being the fact that it is easily “worked”. You can cut it with home tools, and you can drill holes in it as well. It is not as cheap as glass, but it is certainly affordable enough.

Ok, so we are going to discuss how to make a lid for your tank, out of acrylic. You will need a few tools for this project. You will need some kind of saw, preferably a table saw or a circular saw. A jig or scroll saw will also work. If you don’t have access to any of these tools, a sharp hand saw can be used with some patience. You will also need a drill, and a 1” hole saw. You will also need a hack saw to cut the aluminum channel we will use to reinforce the acrylic. Lastly, you will need a tube of silicone caulk, and a caulk gun. If your lid is small enough, you may be able to get away with just buying one of those smaller squeeze tubes of caulk. The last item will be some sheer fabric, which you will use to cover your vents.

Ok, so ready to start? First, measure the top of your tank. No need to get too exact at this point, just the general idea. Most larger hardware stores now carry ¼ inch acrylic, but you might call first just to make sure. It is also possible that they will cut the acrylic for you. If this is the case, then you will want to step back and do some careful planning to make sure you get your cuts right. We’ll cover more about this in a bit. Assuming you can only get the 1/4” acrylic in a size which will require you to alter it, go ahead and get a piece which is larger than your tank top. Now head over to the shaped metal area. Most of these stores will offer a selection of long sections of various metal shapes. You are looking for a “u-channel” that is wide enough to accommodate the acrylic. I’ve found that most stores sell a u-channel that is aluminum, and that the acrylic will slip into with only a small amount of wiggle room. Get an eight foot length of this product, or two if you are doing a twenty gallon or larger tank. Pick up any of the other items you need, and head on home.

Once you are home, do some careful measuring of the opening of the top of the tank. Get a piece of paper and draw out a plan for the lid you will be building. You will need to allow some room for the u-channel that you are going to use to band the outside of the acrylic, so measure the thickness of the u-channel and add an eighth of an inch on each side for the silicone and just for wiggle room.

Cut the acrylic panels to the size you have determined. Now you will need to cut the u-channel to fit around the sides of the acrylic panels. A variety of saws can be used to cut the u-channel, but the most commonly available is a standard hacksaw. Other saws that can be used include miter saws, or jig saws. However I’ll proceed with the assumption that the tool used will be the hacksaw. If possible use a miter box, this will allow you to cut the u-channel on an angle, which will give you a much cleaner look. Dry fit the cut aluminum u-channel around the acrylic panels, and tape them in place. Then try fitting the two pieces into the top of the tank. Adjust as needed. Do not assemble it at this point.

The next step is to drill your ventilation holes. You have some choices to make here. The simplest design is to put a series of holes across the edge of the lid that will be closest to the front of the tank. You can add to the ventilation by putting a small computer fan over a hole at the back of the tank. You could put this fan on a timer or a switch, and have it exhaust air out of the terrarium. This would cause room air to be pulled in through your holes on the front of the tank, and help to dry the front glass of the tank. You will be drilling several holes in the front edge of the piece you will be using as a door, so the holes are as closer to the front edge of the tank. We usually use a one inch hole saw to make the holes, but overall the size of the holes isn’t that important, its more important to get enough holes that there is some airflow, across the entire front of the tank. If using one inch holes I would go for one hole every three or four inches. You can always close up part of each hole with a bit of clear tape, but you cant easily make more holes when you are done. To drill the holes make sure you put a piece of wood behind the acrylic as you drill it, it will be easy to crack the acrylic when you are drilling the holes.

If you wish to go all out with ventilation, you can add the fan to the lid. I would recommend putting the hole for the fan at the rear of the tank. The smallest fan we offer is a 2 inch fan, so you will need a 2 inch hole saw for the fan hole. By the way, if you are not familiar with the fans I am recommending, these are the so called “muffin fans” or computer fans. These fans run on DC current, which means they require an adapter or transformer to run, on household current. It can be difficult to find these fans and the correct transformers. We offer a couple of different options in our store.

Once you have the u-channel cut to length, and the holes have been drilled in the panels, you can “glue” it together. Run a thin bead of silicone in the bottom of the u-channel, and press the acrylic into the channels. Get it all put together and let it sit for a few hours. Next we are going to cover the ventilation holes. The fabric we use is a nylon sheer material, which we purchase at a fabric store. If you like, contact us, we’ll send you a piece of the fabric for you to use. Beware of insect screening, the holes are too large and will allow the fruit flies to get out. If you find another option, by all means use it, and let us know if you think its superior to our ideas!

So, on to applying the fabric over the vent holes. First find a round object that is a bit bigger than the holes you are going to put the fabric over. Then you can use a magic marker to draw a circle on the fabric, and cut it out with a sharp pair of scissors. Alternatively you can use an exacto knife to cut around the template, just make sure put something under the fabric so you don’t score the table.

Use some sandpaper to rough up the area around each hole, then use some of the silicone to stick down the fabric over the holes. Silicone doesn’t stick well to acrylic, but if you are careful it will stay on for a long time. You can also “reinforce” the acrylic, by using something like clear plastic cut into rings to go around the holes. This will allow you to create a thicker layer of silicone. You can add to this by using some small screws. Predrill the holes for the screws, then put the small screws through both the clear plastic ring and the fabric, into the acrylic. Put a little more silicone over the top of the screw.

There aren’t many other options for sticking the fabric to the acrylic, although if you wish for a more secure, simple and permanent fix, you can source some Weld On 16, which is an acrylic cement. This product is available online, but it becomes an expensive prospect by the time you pay ten or so dollars for the tube of cement and then another seven or eight for shipping. If you decide to order this product or purchase it locally, see if you can buy the little nozzle that fits on the tip of the tube. Once you have the product, simply apply a generous line of it around your hole, then press your precut fabric over the hole. Make sure the fabric becomes soaked in the cement, if necessary you can add a bit of the cement back over the top of the fabric and smooth it into the fabric.You will want to use latex gloves or at least some food wrap film to prevent the glue from coming into contact with your skin. You will get a cleaner look if you put the fabric on the inside of the lid.

If you plan to incorporate a fan into your lid, you can add it now. As mentioned before, the ideal place for it is on the back panel. However it is possible to use a fan on the front panel, say placed in the center hole of your array of holes across the front of the lid. Obviously the fan blows air into the tank if placed in one direction, and vacuums it out of the tank when placed the other way. You can always turn it around if you think it might work better the other way. We use small screws to attach the fan to the acrylic lid, but you can also use a bit of clear packing tape, or even a dab of silicone at each corner of the fan. If you are using the fan on the back panel, and you have any type of enclosure for the light fixture, you should consider not blowing the fan into the tank, since it will be taking air that is likely to be hot into the tank. At the front of the tank its probably best to blow the air into the tank, as the fan is probably a bit more efficient at blowing air into the tank than it is pulling it out.

As mentioned earlier, you will want to monitor the fan and how much it is drying the tank out. You definitely will want to turn it off at night, and I think its unlikely that the fan can be left on all day, without drying the tank out too much. A good strategy would be to set the fan up on a timer, and let it run for a half hour or so prior to what you anticipate are going to be peak viewing times. If a half hour is not enough to clear the front glass of the tank, then go to 45 minutes or an hour. Or you could just let the fan run every day for two or three hours, during the middle of the day. The key is to be able to control the fan, either with a timer or a powerstrip that has a switch on it, so you can just flip it on when you need to. Your frogs won’t suffer any ill effects if you leave the fan on for too long, or if the tank is too dry, at least not in the short term. What will happen is that the frogs will not be out and visible when the tank is too dry. When you notice that the frogs are not visible and seem to be hiding excessively, its time to increase the humidity. To repeat though, it’s not a problem for the tank to be a bit dry for a few hours each day.

With or without the fan on the tank, you can tinker with the over all humidity in the tank by adjusting the size of the holes along the front of the tank, by covering part of each one with something like a piece of tape. Watch your frogs and evaluate the need for humidity based on their behavior. You can also use adjustments in your lid to stimulate breeding. For instance some dart frogs will respond well to a period of relatively dry conditions, followed by a period of very high humidity and increased misting, along with additional food. During the dryer seasons in the rain forest, dart frogs tend to retreat to various hides under logs and rocks, or other crevices in the forest floor. These dry conditions doesn’t cause any harm to the frogs, but it does mean they won’t be visible or breeding during these times. Just make sure that if you do allow the tank to get dryer for a while, there is still somewhere in the tank for the frogs to get wet. Make sure the tanks substrate stays wet, and you will be fine.

At this point the lid is basically done. You can use a small drawer pull or handle to open the lid. You don’t really need a hinge, and it can be difficult to fix one to the lid, with the aluminum channel, but if you really want to hinge the lid, you can probably find a set of hinges that will work.

The same basic design can be accomplished with acrylic and wood, instead of the aluminum channel. The result is a bit more decorative, although its not as easy to accomplish. Here we use a router to cut a notch out of the edge of 1”x1” material, which we then seat the acrylic in. You could also use a table saw to run the 1x material through, passing it through twice, against the fence to cut the notch out.

Hopefully you find this tutorial useful. Please let me know if you have any input on this, or if you would like to provide a step by step photo set of you building your own lid, I’ll be happy to provide compensation of some sort!