RES Stopped basking

Question
My RES stopped basking about 2 weeks ago. She also seems to go to sleep before I turn off her lights. These are both new behaviors but it is lack of basking that really concerns me.
She is 3-5 year old res. I have had for a year. She 7-8" long. Very active. Her aquarium is 90 gallons about. Her water temperature is usually 82 degrees. She eats red leaf lettuce for 2-3 days and then I give her a good protein meal made of mainly pellets with some dried insects. She is a very good eater but I have never been able to get her to eat other fruits or veggies. I use a canister filter I clean about every 30 days give or take. I do a water change about every 2-3 weeks. She has used the basking area provide consistently until now. I use one of those higher end usb lights. The bottom of her tank has river stones.

Thank you for any help you can provide

Answer
Hi Geoff,

Ugh, I'm sorry, I answered this a couple days ago but it didn't go through.  Grrr...

Anyway, first I'd like to commend you on your dedication to your turtle.  Typically I get questions from people who have their turtles set up in tanks that are much too small--in fact, I'd say that most problems I get are due to overcrowding.  It's really great to hear from someone who actually has a tank that's more than big enough.  So thumbs up to you.

Your RES is probably at least five years old.  A 7" three year old would have grown too quickly and probably have some level of shell deformation.  Just FYI.

OK, the lack of basking issue...  The water temperature is really quite a bit too warm.  It should be more like 74-76 degrees.  As you probably know, you want to see a good balance between swimming and basking.  The way to achieve this is to have a warm (88-90 degree) basking surface and then a 10-15 degree cooler water temperature.  This causes the turtle to bask, swim, bask, swim, etc. in order to achieve a balanced body temperature in the mid-80s.  When the water is too warm, they don't bask enough and this can lead to significant skin and shell issues.  So you need to drop the water temperature about 8 degrees.  Do over the course of about a week, a degree or two at a time, so it's not too much of a shock.  After that you should start seeing more basking behavior again.  

The other contributing issue could be your UVB bulb.  It sounds like you're using something like a ZooMed Powersun (which is the bulb I recommend) for basking/UVB.  Those bulbs do need to be changed yearly (tube bulbs every six months), because their UVB output drops significantly after that.  It helps if you write the purchase date on the bulb with a sharpie so you don't forget.  

You're right in that her diet could use some improvement.  Pellets are great; try adding in some other sources of animal protein such as worms, bloodworms, dried shrimp, feeder fish, etc.  It's also important that she eats greens or veggies several times a week, since RES become more vegetarian as they get older.  Lettuce is OK on occasion, but it's not very nutritious.  Better choices are dandelion, turnip, kale, mustard, collards, etc., along with carrots, squash, etc.  If she won't eat them, try cutting back on food for a few days so she's good and hungry and then offer just a bit.  A turtle her size doesn't have to eat daily anyway, and a hungry turtle is more likely to try something new.  Plenty of variety is always a good idea, because it's very common for turtles to develop dietary habits and then refuse to try other foods.  I'd also put a cuttlebone in the tank for her to nibble on for additional calcium as desired.  

If dropping the water temperature doesn't improve the basking issue, let me know.  But overall, I think you're doing a good job with her!