Yep. Cancel your order on that 16 x 16 x 30 cage. That's what you should already have him in right now. He will need to be in a 24 x 24 x 48 cage within a few months.
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As for the dripper plant and the fake Amapallo plant you posted a link to.... Don't use the dripper plant. Those are junk. The pumps on them suck. Very poorly made. They also work by dripping water into a collecting cup at the bottom, and a pump sucks the water out of that cup, back up a hose, and spills it back out onto the plant dripper leaves. This means that the SAME WATER will be cycling over and over and over, collecting dirt and dust on it's way down each time. Your chameleon needs FRESH water. Not re-cycled water. This can be achieved by several misting sessions a day, or placing a dripper on top of the cage filled with water, that will drip water down onto the plants in the cage. This will be filled with new, fresh water once it is out. Or you can change the water daily, whichever you prefer. If using tap water, be sure to add a bit of ReptiSafe to the water to make it safe to drink for your chameleon.
The Amapallo plant is okay....
IF YOU HAVE LIVE PLANTS as well. You really need live plants in your cage. One single fake plant will not suffice. You are trying to imitate their natural environment, which has WAAAAYYYY more than one mingly little plant. These animals live in forests - decorate your cage as such. Add more plants, LIVE plants, and lots of them. Humidity will keep at recommended levels much better with real plants in the cage as well. Just make sure your real plants are planted in organic soil, and have rocks or screen covering the dirt so that your chameleon doesn't accidentally ingest it.
As for the humidity and temps in a screen cage -
@absolutbill explained that - just wrap a couple sides of the cage in plastic to retain humidity if you are having trouble. Real plants will greatly increase the humidity and make it not so hard to maintain. As for the temps escaping in a screen cage like you was asking about.... you WANT the lowest temp in the cage to be about room temperature, or about 68-75 degrees. The top area of the cage will still be warmed by the heat bulb and create basking temps which will allow your chameleon to move in and out of the light in order to regulate his body temperature.
How do you monitor humidity anyways? In your last post, I asked if you had any temperature or humidity gauges. You stated that "AS so a temp guage though....The pet store owner never told me that i would need one and that the heating lamp would be okay." ................... Well, the pet store owner was wrong, and you
NEED to get a gauge to monitor temps. How else are you going to know if your cage is becoming too hot or too cold for your reptile? You never said if you had a humidity gauge either...... I never saw one, so I'm assuming you don't have one. You
NEED to get one of those too. Otherwise, how else do you know what the humidity is inside of the cage? You're pretty much just guessing at this point. And as with all pets, it's best not to just guess on things. Go get some gauges. You can get them both as a single dial unit all-in-one for less than $15, or you can spend a bit more and get digital ones. You absolutely need them though, as they are essential to the well being of your cham.
Lastly, as for the substrate tray you posted a link for. NO SUBSTRATE. All a substrate does, is harbor water which in turn, breeds bacteria. The bottom of the cage should be a screening or it should be a piece of plastic (the kind that typically come with cages) with some holes poked into it for water drainage into a tray below. Only female chameleons require substrate, and dirt substrate at that, to lay their eggs. You refer to SMAUG as a "he" so that's telling me that it's a male, and therefore, does not require the use of a substrate tray.