Monitors of all sizes have "needs". Its not wise/good/recomended to use cages that do not meet their needs. One reason monitors are not commonly bred, or success is so rare is, People try to fit them in less demanding type of reptile cages or fish tanks.
If you take your fish tank, its two feet deep, the reason is, fish need that much water to get along. Why not give fish two inches of water? or one inch??? Of course you could keep mud skippers in shallow water, but not most fish.
Mind you, fish takes can be made to work, but the keeper has to be creative and intune with his animals. In that case, they will most likely go in another direction.
Monitors of all kinds, Use their substrate like fish use water. A good amount of substrate depth is 2 feet, kinda like that fish tank. Of course you can get away with less, 18 inches or so, maybe even a foot, but the lower you go, the worse it is for the animal and the poorer they do. You see monitors actually live in the substrate, they live like gophers and voles and moles, and mice and rats. All of these live in substrate(burrows) but to different extends.
Even aboreal monitors spend the vast majority of their lives in the substrate, only their substrate is high up in hollow trees.
So fish tanks do not work out for adult monitor species. They are OK, for raising babies.
So any of the fish tank cages, or fish tank derived cages, you know, reptile kit, at petshops, are not suitable for monitors. That is unless you only want to take care of it for a short time(then it dies) and you can get something new. You can do that, but I or others will not recomend that or help you do that.
So with monitors, you kinda have to go to the trash pile and make up something that works. That is, use a cage that fits the animal, not simply what will hold it captive(until it dies)
A cage is only a tool to build your reptiles. As an example, if you have to screw in a large screw, you would not use a hammer, it could work, but the screw would most likely fall out later. Or use a saw, a saw is a tool what not meant to screw in screws. Maybe use an electric sander, dang thats a fancy tool, but it won't work. How about a prybar, thats getting close, if the screw is big enough you could actually screw it in, but its really ackward and you keep banging your head with the other end of the prybar. Oh I get it, use a screwdriver. There are all kinds of those, some you have to actually twist and others all you have to do is push a button. But then some do not work either. Wrong tip, so you find a screwdriver with the right tip and Bingo bango, you are in river city. Use the right tools. Cheers
