Posted: Sun Nov 22, 2015 5:53 pm Re: 60 gallon tanke
It's better than a 20, but they'll outgrow the 60 eventually. 10 gallons per inch of turtle is the basic rule of thumb, and your RES should eventually push 10" each.
If it's narrow, I assume it's tall. Typically, they don't need the extra depth, and prefer the room to swim around... but compared to a 20 gal, they'll be thrilled. I guess it depends on how good of a steal it is, and whether or not you can wait to afford (or find a steal on) a better option.3
Also, if you have a turtle topper, why not fill it up more and forget about the floating dock?