Green Tree Monitor (Veranus prasinus) enclosure evolution


This is a comprehensive post on how I approached housing V prasinus green tree monitors over the course of our first four months with these animals. My objective was to provide our V prasinus monitors with as much space as I could, while also providing an enriching, naturalistic vivarium based on the methods I have used for a decade in housing poison frogs. Though the frog hobby and monitor hobby may seem totally unrelated, may key techniques are common for tropical setups, such as:

  • Substrates & microfauna,
  • False bottoms and water management,
  • Misting systems and climate control,
  • Lighting & automation,
  • Hardscaping, glues, foams, and backgrounds, 
  • Live plants.

Bioactive is a term often used in the reptile hobby. Naturalistic vivaria have been in use for decades in the frog hobby, and many key techniques (such as drainage and false bottoms) are more advanced in the frog hobby when compared to typical techniques in the reptile hobby. This page explored blending these husbandry techniques to adapt them to tree monitor housing. This post takes you through how we ended up with this:

We started with a quarantine enclosure of 3’x3’x1.5′, then moved to a phase 1 permanent enclosure of 4’x4’x2′, then added another upper section to yield a final permanent enclosure size of 4’x6’x2′.

We will step through the build process for the permanent enclosure that is based on two Zen Habitat PVC kits that were highly modified. We settled on these kits because they were light weight, PVC based, and readily available. The base frames were sturdy and easy to work with, 


Quarantine enclosure

We’re describing the QT enclosure here because we used this as a test bed for key ideas prior to full implementation in the permanent enclosure. Key elements we experimented with were false bottom design, lighting design, and humidity control. 

We quickly discovered that the typical “bioactive” false bottom simply won’t work for a monitor. LECA false bottoms with a simple screen even siliconed to the perimeter of the enclosure was not resilient enough to prevent a tree monitor from destroying the screen layer by digging through the substrate and peeling back the screen.

This did not prevent us from developing an alternative false bottom design. We settled on an egg crate frame, with acrylic panels zip tied to the top of the egg crate. The acrylic was drilled with a 1″ grid of drainage holes. The acrylic was cut to fit tightly to the perimeter of the tank. This yielded a resilient false bottom design that was resistant to digging. Solar screen was used to ensure soil didn’t fall through the drilled holes. The solar screen was reinforced with a bead of silicone around the perimeter of the tank. 

This false bottom approach was more complex than the usual egg crate plus screen used in the frog hobby, but the addition of the acrylic panels, though a bit more costly and time consuming, worked well for housing V prasinus monitors. After 2 months they have not broken through the false bottom design. 

Phase 1 permanent enclosure

Enclosure selection

The Zen Habitat 4’x2’x4′ PVC enclosure was selected as the base platform for this build. I researched extensively on what enclosure types were available commercially, and what options I had for home built. I did not want to attempt glass with this large of an enclosure – I was looking for something 4 feet wide and 6 feet tall, and glass panels that large would be difficult to manage. I was looking to avoid plywood, as the weight of the build and movability of the vivarium at this scale would be difficult to manage. PVC panels have been growing in popularity in the frog industry, so I decided to narrow my research to PVC based solutions.

There were a few commercial PVC options available, and most were custom built orders with significant lead times. I wanted to get our monitor into a permanent viv within a few months, rather than a year, so I started looking at sourcing my own PVC panels and additional materials. I was concerned about my ability to seal the seams, and sourcing a new material I had not worked with.

About that time I came across Zen Habitats. I liked a few things about their designs:

  • modularity
  • aluminum frame
  • built in sliding door tracks
  • galvanized (not really) screen top
  • PVC panel option

After investigating a bit, I decided to marry two Zen Habitats enclosures together with High Bond Tape. I liked the approach because I could focus on a base 4’x2’x4′ build, move my prasinus, then expand vertically in a second phase. I could also have a larger viewing area with four separate sliding doors, allowing for modular doors that I could replace with reasonably sized glass panels. I liked the idea of a strong aluminum perimeter frame, with slip in PVC panels. The overall weight was reasonable, and since it was fairly modular, it could be [somewhat] easily disassembled and transported if we moved.

So I ordered a base Zen Habitats 4’x’2’x4′ unit.

Enclosure assembly and waterproofing

Zen Habitats has plenty of details on how to assemble their units. The main change in approach I used was to fill all panel tracks with a thick bead of silicone. This silicone was used to form a waterproof gasket the panels would sit in. The aluminum provides the structural integrity. I fully assembled the unit, seating the lower 12″ of all seams in silicone. I let that cure overnight.

The next day I filled the unit with about 2 to 3 inches of water and let it sit outside for 24 hours.

No leaks! I emptied the water, then started drilling for bulkheads. I drilled four bulkheads for misting heads, and one bulkhead for a false bottom drain. I taped the inside of the viv and drilled through the back. Note that I used the plug provided by the manufacturer since I would not be using it.

Here are the bulkheads fitted to the upper back panel:

I didn’t take pictures of the stand build. It’s a fairly basic approach with a 1″x4″ support frame screwed together and supporting 1/2″ 2’x4′ plywood panels. I used 1/4″ plywood panels to sheath the front and sides, but opted to use cabinet magnets to attach them so any panel could be easily removed to access equipment housed in the stand (electrical and plumbing).

The assembly went into a nook in our kitchen that was intended for a china cabinet. We wanted our V prasinus monitors in our main living area, so no china cabinet for us!

Our assembly is now about 6 feet tall. The stand is 4’x2’x2′ – this was done to provide flexibility in height for storing a large misting reservoir, and for keeping my electrical up high and away from my pump and water source.

Hood construction

I’ve been building vivarium hoods for over 10 years for my frog hobby. I used those strategies for this vivarium build. I use a few strategies in my hood approach designs:

  • I prefer low profile hoods, so I use 1″x4″ perimeters which form the height, and 1/2″ plywood for the top.
  • I used weather stripping around the perimeter of the hood to seal the hood to the tank. This allows me to control airflow and venting.
  • I use a blow hole at the top of the hood to control exhaust flow. This also allows me to control airflow through the viv, which allows me to control humidity.
  • I prefer daylight LED lighting, but I also added heat and UV lamps to this design, each on separate circuits.

The top plywood sheet was set flush with the perimeter trim for a clean look. A central 80mm blowhole was drilled for a computer fan exhausting air from the hood. The wood was stained and sealed with a varnish.

The interior of the initial hood lighting layout was divided into three circuits.

  1. All round 5w LED spot lamps were soldered to a 100 watt outdoor waterproof power supply.
  2. Two UV heat sockets were installed on the left on a second circuit, aligned horizontally with the hood.
  3. Two vertical sockets were mounted on the left for low profile halogen heat lamps. The entire left side of the hood was lined with reflective aluminum tape. The tape helps insulate the wood from the heat lamps.

I ended up adding fourth circuit with a “downlight” that was in front of the 80mm fan to throw additional light to the lower portion of the viv. Here is a closeup of the basking side of the hood:

I prefer a “random” spotlight pattern in the viv. As you move down the canopy this creates more directional “spot” lighting in certain areas. I use the wire leads to help randomize the LED patterns as I screw the sockets in place:

And here we are with the hood installed and tested:

False bottom construction

A false bottom was constructed with egg crate light diffuser and zip ties. A base frame was constructed below a complete 2’x4′ diffuser sheet:

The diffuser sheet was then covered with an acrylic sheet which was zip tied to the egg crate frame:

Black zip ties were used as handles, fixed to loops in the zip ties used to fasten the acrylic to the diffuser. The false bottom unit was then put in place in the viv:

This is a close up of the hole pattern drilled in the acrylic to facilitate drainage. Some holes toward the perimeter were expanded to 1/4″:

Though difficult to see in this view, the cross member supports of the false bottom actually rest on the aluminum lip of the frame. This takes pressure off the bottom PVC plate.

This is a view from the front of the viv of the bulkhead drilled for drainage. You can see the sloppy silicone job I did on the perimeter of the base – all PVC panels were floated in a thick bead of silicone that formed a gasket within the aluminum slots:

Close up of the bulkhead:

I did not capture a picture of the final step which was the application of a fiberglass solar screen sheet on top of the acrylic. This will prevent soil from falling through the drainage holes. A bead of silicone around the perimeter of the false bottom secured the screen in place.

This false bottom design may seem excessive, but the acrylic sheet was used to prevent prying monitor claws from peeling back or puncturing typical false bottom construction methods. If they dig sufficiently deep enough, they could pull back the screen layer, but they will not get past the acrylic sheet. This should discourage further digging and preserve the integrity of the false bottom.

This was by far the most complex false bottom I have built, but I am considering the acrylic method for my frog vivariums, as I have experienced multiple false bottom failures after 7-10 years where the screen or landscaping fabric fell through the light diffuser supports. This could be an interesting strategy for relieving the force placed on the fabric without an acrylic sheet.

Background framework construction

The next concept was the creation of a full background. I wanted to provide our V prasinus monitors with the ability to scale all the walls in the lower portion of the viv. I wanted to use a base of cork tiles, but I was concerned about how well the background tiles would adhere to the PVC panels. I decided to build an egg crate diffuser frame and attach the cork tiles to that with a combination of glue and zip ties. Cork flats and rounds were then zip tied to this frame, and expanding foam, gorilla glue, and spagnum moss were used to finish a more naturalistic look.

This frame could then be inserted into the viv, resting on the false bottom. The frame was secured in a few key locations to the frame of the viv with zip ties, but the background can still be fully removed if the viv needs to be disassembled.

First I assembled the 2’x4′ diffuser panels and trimmed them to fit the inner dimensions of the viv. I coated the back of the cork panels in silicone and placed them on the diffuser frame. I then zip tied the edges of the panels to the frame for added support.


Once the framework was complete I added cork panels and tubes to provide climbing surfaces and hides to provide for a more naturalistic look. Here again I zip tied the cork panels to the diffuser framework.

You can see the rear view of the background with a thin coat of silicone and zip ties running through the entire background.

Once inserted in the viv I added larger cork rounds across the panels to help square the background to the viv:

Foam and Gorilla Glue

The next step in the process was to apply expanding spray foam to areas of the background and carve for a natural look. Then a coating of Gorilla Glue was applied and ground sphagnum moss was pressed into the glue. This yielded a consistent natural look to the background. I covered all the track in blue painters tape to ensure the foam didn’t get in the track.

Misting system

I decided to piece together my own misting system since I had so many spare parts from my frog hobby. I have a box of fittings and tubing that I can draw from, so I needed:

  • a pump
  • mist heads
  • reservoir
  • timer / controller

Commercial kits are available, but their prices have been rising. I was looking at $200 plus for a basic system shipped, which was pretty expensive. The other negative was the kit wouldn’t be compatible with my home automation through HomeKit, so I started looking for a less expensive alternative.

Misting system pump

I used an Aquatec CDP 6800 pump ($68) with a power supply ($16). This pressure booster pump is equipped with 1/4″ quick connect inlet/outlets and provides 110 psi which is more than enough to power 6-8 mist heads.

Misting system heads

Commercial mist head assemblies can cost $15 to $30 each. You’re better served looking for bulk quick connect fittings and patio mist heads which typically are significantly cheaper. I picked up 10 stainless steel mistheads with an assortment of quick connect fittings for $16 on Amazon. I also had extra quick connect elbows from prior purchases for my frog misting setups, but they run about $3 a piece. All in, I was looking at about $6 a head.

I initially built out dual head assemblies:

Here was a test fit prior to installing the background:

I found the dual head assemblies put out more water than I wanted with this pump. I ended up using 4 heads in the lower viv, and 2 heads in the phase 2 section for a total of 6 mist heads in the final viv.

Misting system resevoir

I already had a 5 gallon bucket that I intended to use for the reservoir. I did pickup a gamma seal lid ($16) for the bucket. Here’s a picture of the entire misting system setup. The bank of HomeKit wall plugs run the lighting and misting:

Misting system timer

I opted for a wall switch controlled by Apple’s HomeKit. This integrated directly with the home automation app I have been using to control my lights, so I wanted to do something simple with a $20 wall plug.

The plot on the right runs the misting system. The three plugs on the left run the lighting system. The square plugs are around $20 and are simply on/off. The plug on the left is a dimmer that runs the heat lamps; it’s about $40.

I think they like it (so far)

Phase 2: 4’x2’x2′ canopy extension

I wanted to lighten the look of the top of the enclosure. The bottom was fitted with 100% climbing surfaces, but the naturalistic background treatment created a look that was quite dark. We liked this look for the lower portion, but we wanted to try and simulate a tree canopy in the upper section, so we decided to go with a simulation of the sky on the upper panels, with cork round tubing as the main framework, as opposed to the cork panels used in the lower section. 

I started with a blue-tinted vinyl dye base coat. This type of paint binds nicely to a variety of plastics, though it is three times the cost of typical spray paints. So, given the cost, this was only used as a primer coat.

Following an initial vinyl dye base coat, I switched to a less expensive Rustoleum paint for the final coat. You can see the difference in colors as I was applying the second coat:

All three upper panels in the 2’x4’x2′ section were painted with three coats of high gloss blue:

The top screen of the enclosure was painted with four coats of high gloss white. I found during our initial experience with the Zen Habitats 4’x4’x2′ enclosure the top screen does not appear to be truly galvanized, but rather it seems to be painted silver (at least that seems to be the case with my two screens). This screen rusted quickly in our high humidity environment, so I pro-actively applied a thicker painting strategy to this top. I opted for white to increase the reflectivity of the screen that would be used under my custom lighting fixture.

Once the paint was dry, I assembled the frame. Since we were expanding vertically by joining two Zen Habitat kits together, I used a very high bond tape to fuse the top frame from this kit to the bottom frame. The plan was to remove the top frame from the lower section, drop the expansion section on top of the original lower section, then replace the top from the original lower section (after swapping out the screen for our freshly painted one).

The first step was to assemble the upper frame, then attach the VHB tape around the perimeter of the frame:

The lower frame and vertical supports were then assembled and fixed to the upper frame with the VHB tape:

The VHB tape yielded a very clean look (see the black line below) as well as structural reinforcement binding the plastic end caps permanently to the aluminum frame:

The blue painted panels were then slipped into place. Note I opted not to use the pre-drilled rear panel with the kit, and instead used the floor as the back panel. I didn’t need the big opening for wiring, I would be drilling my own access holes for temperature and humidity probes, as well as misting bulkheads.

Climbing surface build out

The upper portion of the viv was intended to simulate a tree canopy. I purchased a bulk box of cork rounds instead of flats from for the upper build out to simulate tree branches. I also had some live oak branches collected locally and debarked that I wanted to incorporate as climbing surfaces.

We played around with various layouts before I fixed them to the frame and PVC panels by selectively drilling holes in the inner portion of the aluminum frame tracks that set the panels, as well as a limited number of holes through the PVC panels themselves.

Misting expansion

I did add a single bulkhead running a dual misthead in the upper section of the viv. That yielded a total of 6 heads in the viv.


Bioactive substrate

We’re using an approximation of an ABG (Atlanta Botanical Garden) mix, based on peat moss, tree fern fiber, repti-bark, and charcoal. This mix formed the base for all soils used for the main substrate layer and plant pockets throughout the viv. The bottom soil layer of substrate was topped with about an inch of dried live oak leaf litter purchased from a commercial vivarium supply outlet. This litter is collected in areas free of pesticides.

Temperature, humidity and misting

I’ve instrumented the vivarium with three sets of probes for continuous temperature and humidity monitoring. I have the lower right, mid left, and upper left portions of the viv monitored. I’m using three Elitech GSP-6 units for data collection. They will continuously record a data point per minute, set to circular logging, so I will always have 11 days of data preserved in the recorder.

This was the monitoring setup for phase 1 with two sets of probes – I added a third when I expanded the viv with phase 2:

The probes were pushed through access holes drilled through the rear PVC panel:

A dab of silicone was applied to each hole after the probes were inserted.

I am going to tune the location of these probes over time. For now, the two located in the lower portion of the viv are recording really high RH values typically in the 90% range. The upper portion of the viv is typically in the 70% range.

I am still tinkering with heat pads. I applied two pads to the lower rear portion of the viv. The Zen Habitats PVC panels were designed to work with undertank heating so I decided to give it a go.

I noticed via my instrumentation that the heat pads didn’t seem to increase tank temperatures above ambient. I suspected I was suffering too much heat loss on the back panel, so I built an insulated foam box that I fixed to the back of the viv over the heat pads to try to retain heat and transfer it to the viv.

Live plants

A key challenge we took on was a commitment to using 100% live plants in the enclosure. This was a pretty tall order given the size and number of claws that will be in this viv, but it was a concept we felt strongly about.

We settled on pathos as the main base plant, with a few specimen plants with larger bromeliads and larger, fast growing, house plants. We had one complete failure with a small palm tree – our V prasinus monitors are quite active, and often jump from branch to branch. Periodically they miss their mark and land on plants. Within a few weeks they had pulverized the palm, so we removed it and focused on tiering the viv with layers of faster growing pothos.

We added bromeliads for a touch of color:

The tree monitors are simply brutal on the live plants. You absolutely need to use fast growing plants in the lower portions of the viv. Our two V prasinus jump from branch to branch…and they miss their targets…a lot. We have shredded plants in the lower portion of the viv where they land on the plants. I’m happy to sacrifice these plants for cushioning of their falls.

Final thoughts, 4 months in

Height matters. There was a noticeable difference in the behavior of our pair as they were able to move higher off the ground. At 3′ in QT with a 2′ stand we were above them and they were quite skittish. At 4′ with a 2′ stand, we were at eye level with them in phase 1, and they were still uncomfortable.

In our final phase 2 design, they had 6′ of viv on a 2′ stand, so they are 8′ off the ground. They tower over us, and enjoy their perches looking down on us. We chose to house them in our kitchen, one of the most active rooms in our house. We did this so they would get used to us, and it has worked well so far.

Our two animals were likely wild caught. They don’t like being handled, and won’t eat off tongs yet. After a few months of work, they allow me into their viv to place food in their bowls, as long as I am on the opposite side of the enclosure. They will tolerate a shower with a hand mister, sometimes taking a fresh drink as they are sprayed down. That’s about all the interaction they will tolerate right now. We will keep building trust and working with them.

They are truly exceptional animals; I hope you come away from this blog more informed, and more UNLIKELY to take on housing a tree monitor lightly. These are animals that require a high degree of precise care, and hopefully you see that after reading through the planning that went into setting up their enclosure.