how would yuo put an under tank heater in a 90 gallen tank. b/c i have ont lamp till i get a nother hole cut in the top. so i was thinking put an under tank heat on the side where there is no lamp would .that work.
UTHs are not really functual for an iguana as they will not usually be in the bottom of the tank. It is not natural for them to seek belly heat. Unlike snakes that will crawl onto a warm surface to heat up iguanas are genetically wired to bask in the sun. The UTH will only heat a space on the bottom surface of the tank and not heat the air inside the aquarium.
Where in the country are you? Many places it is warm enough that you don't need much additional heat.
more later time for my final exam now
ok that final is over.
Granted I just moved to the south and it is currently sub 50 degrees where I used to live. But I have not needed a to heat my cage for a while.
However if you are living near the arctic circle or someone in your house likes to cool the place to meat locker levels try making a light cage from wire mesh and putting a 40W bulb in that. Put the whole thing in the top corner of the tank under the lid. I am thinking of wire mesh enclosing a clamp light base that then hooks onto the top edge of at least two sides. Place it high enough that the injured ig can't climb on to it.
Watch your thermometers closely even a 40W bulb will heat a sealed glass box a lot.
side note: I am jealous of that 90 gallon free FISH tank -- take the ig out, reseal it, and fill that puppy -- at least your idea of a small tank is closer to reasonable than many people’s