The Mazuri is good. I use it as I have so many turtles to feed and can buy the big 25 lb bags. A good koi pellet is also a great food and well balanced for most aquatic turtles. It contains both the protein and the vegetable matter - so great for a turtle food.
The curling of the shell is caused by excessive IRA in the basking area. The same thing that can contribute to pyramiding in tortoises. Looking back at your post I get the feeling you are using a Mercury Vapor basking bulb? If so, that could be the issue. I like to use a low wattage incandescent bulb for basking along side a small tube fluorescent for UVB. The UVB should extend over the basking area AND a portion of the water where there is some plants to hang in. A good amount of turtle
I've already learned more than i thought i knew. You've all been helpful. I found and ordered a Zoo Med Reptisun 10.0 bulb for uvb/uva.@Markw84 .... Great info and advice. As always.
And he will eat Koi ppellets. Now we'll see how things progress