tank for water turtle

Question
QUESTION: We need a new tank for my son's water turtle (red-eared slider). She is getting so big and has way outgrown her small tank.  I would say she is about eight to ten inches in diameter. What type of tank and filter system would you suggest.  We don't want to invest in the wrong thing.  My son found her on the sidewalk when she was smaller than a quarter. I had heard that they put out a hormone into the water and this will inhibit their growth so that they don't outgrow their habitat. Of course this doesn't happen when you are changing their water.  Is this true or just bs? Any advice you can give would be appreciated.  She is about three and a half years old. Thanks, Laurie

ANSWER: No, there is no such thing as such a hormone as that. Who ever told you that is a freaking idiot. If there were such a thing anyway, it would be cruel and unethical to use it and risk an animal's health for your convenience.

For turtles this big, you are talking a couple hundred gallon capacity, with a dry land area. Outdoor Koi ponds are best. If she doesn't have this, she will not only be deprived exercise and lose muscle mass, but if she ever has to lay eggs the loss of muscle tone can lead to a fatal case of egg binding.

They also need dry land area for nesting behavior and to allow a place for complete dry off to avoid shell rot.

The water should be at least 2-4x as deep as her shell width, and the length should be at least 8-10x her body length. Anything less than that is just cruel, but there are many people out there who keep them in the smallest thing they can get away with and call that acceptable.  

Filtration should be rated for at least 1.5 - 2x the volume of water in the habitat.

You also should have UVB lighting unless you are housing her outdoors.

---------- FOLLOW-UP ----------

QUESTION: omg, I meant that the turtle produced the hormone-not that it was something we do!!! Just like people have hormones. Good God, I didn't mean we would do that!!!!

Answer
The nonsensical-ness of it then would be even more pronounced than a suggestion that it was a synthetic. What would ever give you an impression that a turtle produced such a hormone itself in response to whatever aquarium size you have? That's one of the most ridiculous things I've ever heard.

Either way, whether the suggestion is you doing it, or it coming from the turtle, it is BS.