Habitat - Indoor :: How many gallons do three adult Red Eared Sliders need?

[Matryoshka]

I have 3 baby RES, and I am starting to think about their future.
I roughly figured that they would need about 100g each, and 300g in total. (Ugh! xD)
I am about to move house, and it is something that occurs every 2-3 years I guess, so allowing them live in my family pond, which is super deep, is not a wise idea if I want them to come wherever we are.
The new house my family is considering has a huge balcony on the second level, which are connected to two of the four rooms upstairs. I think cats can't get there, birds maybe yes, but there are blinds. My dad is contemplating to build a glass screen around the balcony to prevent accidents with falling off.
So if we DO buy that house, I was thinking I could use a baby pool for my RES?
Yeah. Any opinions?

[Matryoshka]

*Edit*
My Angelfish tank is about 7-8G. My three babies are less than 3" long each, and if my calculations are correct they can live in the tank until they are over 3".
My friend may be adopting the Angels, which means that my RES can have the tank. If not, i can ask my parents to have the long-unused-and-dusty inflatable baby pool at the balcony, and I can see my RES from the window every day ^^ !
But still B| Answer the question?

[steve]

A baby pool is not very deep, if you want something deep and sturdy look into stock tanks. Water is 8.3 pounds per gallon, so you will be very limited if you were to put them on a balcony.