soft shelled yellow belled turtle please help

Question
I wanted to know what i need to do to keep my turtle alive please. when i went to clean the tank tonight i moved my turtle i noticed that his shell was way to soft. so i am very worried. im not too sure how old it is or what gender i brought them home with me from Florida a couple weeks ago and the only information they gave me was that it was a baby yellow bellied slider.
I THINK THAT THEY ARE A LITTLE BIT BIGGER THAN A HALF DOLLAR
  Right now i have them both in a plastic 4 or 5 gallon tank with  a bridge to bask on. i feed them every three days like they told me. the food that i got them is tetra ReptoMin with 3 different selections. It includes ReptoMin staple diet,nutritious baby shrimp and mini krill treats. they also get these Wardley turtle treats.

Answer
Hi Corey,

Some softness is normal in hatchlings, but if it is very soft (the shell very easily indents if you poke it gently) there is a problem.  Based on your setup and where you got the turtles, my guess is that the softness is due to lack of UVB.  In any case, you need to completely change your setup, because what you have now is completely inadequate.

I'd get a 40-50 gallon tank so that you have something big enough for them for the next 2-3 years.  When they're mature they'll need something closer to 100 gallons, but 50 will give them room to grow.  Then, you need a filter that can handle twice the tank's capacity, so for a 50 gallon tank you want a filter that can handle a 100 gallon tank.  Enough room and clean water are both very important to turtle health.  Make sure the basking area is big enough for both of them at the same time, with room to grow.  You need a source of heat and UVB--I'd get a ZooMed Powersun bulb, which has both heat and UVB.  I don't recommend any other bulbs, because they're too unreliable.  Maintain basking heat at 88-90 degrees (measure in the basking area right under the bulb) and water temperature of about 76 degrees.  The bulb should be on 12-14 hours a day.  Without UVB, they can't metabolize calcium properly and will develop bone and shell softness/deformities.  I think if you get them into a better setup, they should start to do much better.

Also work on getting more variety into the diet.  Pellets are fine, but also feed various kinds of animal protein and greens.  I'll post some links below that will give you some ideas for foods.  Please post back if you have more questions, and I'll do what I can to help.

http://www.redearslider.com/  (The site is for RES, but the information is all good for YBS as well)
http://www.austinsturtlepage.com/Care/care.htm
http://www.austinsturtlepage.com/Care/waterquality.htm
http://www.austinsturtlepage.com/Care/housing.htm