Painted turtle illness? Injury?

Question
QUESTION: I have a painted turtle of undetermined age as it was brought to me as a rescue and I had successfully raised a healthy and happy slider.  His shell is a little under four inches, end to end (not over his dome).  About a month ago I moved his tank under a light designed to grow plants, but I've been leaving his habitat lamp on 24/7.  His water temperature varies between 70 and 74 degrees and I feed him ReptoMin.  Recently, he has begun to show little interest in food, then about three days ago I noticed a dark gray-ish spot on the underside of his shell, but it's not soft - it looks like maybe he scraped himself climbing onto his basking spot.  He seems active enough, but I'm still concerned about his lack of interest in food.  I don't have a vet around that treats turtles, so any info you could give me would be greatly appreciated.
ANSWER: Darkish spots on the underbelly is a form of shell rot- which would not be a problem if the turtle was otherwise healthy. The infection causing the shell rot is coming from the shrimp meal in the Reptomin. (All shellfish carry a bacteria that can infest the scutes of the turtle's shell if they get scratched and the turtle cannot fight the infection.)

Try this:
- Boost tank temps about 5-10 degrees.
- Make sure tank is big enough (aim for about 40 gallons of water if possible.)
- Turn off lights at night. Use an aquarium heater for water temps. (You may need a heater guard as well.)
- Get and use a bulb with UVB rays- not only will it help with calcium metabolism, it will help kill germs in the tank.
- Every day, take him out of the tank and soak him in a solution of Betadine solution (provodine iodine) diluted in enough water to make a 'tea-colored' bath. Keep his head out of it, but soak the affected areas. Try to soak him for at least 15 minutes, the longer the better.
- After the soak, keep him dry for about an hour before rinsing the solution off and returning him to the tank.
- You can try a sulfa block in the water. I don't have a lot of faith in them, but it might help.
- Offer some earthworms, crickets, krill, shrimp, etc. as well as the pellets for food.

Try http://www.austinsturtlepage.com for other ideas and info.

Good luck!

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

QUESTION: Thank you for all of the info.  I've done everything you suggested, except for the size of the tank.  I've got him in a 25 gallon and you suggested a 40.  I don't have the capital to purchase another tank.  I am pretty fastidious about the cleanliness and I try to care for and accommodate him in anyway I can, but can that possibly make up for a 15 gallon discrepancy?  I want him to be happy and healthy, so if I can't achieve that goal in the tank he's in then I'm prepared to either save for a bigger tank or find a new home for him that is more suitable.  So I guess my questions are:

1. Is there anything I can do to make this tank work beyond what I'm doing now (including your new suggestions)?

2. If not, is it possible for you to give me an approximate time frame during which I could keep him - happy and comfortable - in his current habitat until I find a bigger tank or find a better home?

also...

3. Are live plants in his tank a good thing or not?  I have a friend who's a horticulturist and she's offered me all sorts of aquatic plants, but I'm unsure if I should or not.  Will his tank require more care with live plants?  Are there certain plants that are actively bad?

My ultimate goal is to keep him as he provides endless entertainment (we don't have television in our house so we frequently refer to he and his habitat as "turtlevision" because everyone loves to just sit and watch him do his "turtle" thing)

I really appreciate your help.  

Answer
The problem with a small tank is less hygiene and more comfort, security, and territory. Most of us cannot afford a glass tank and use big plastic tubs instead- nice and cheap- and translucent plastic is less stressful as well (turtles are stressed by glass walls they cannot swim through.

It will not kill the turtle to be in too small of a tank for a while, it is just better to be in a big one.

Live plants are great- they add many benefits, including a possible food source. Go for it!