Try to keep your turtles' water at a constant temp, for their age 1 1/2 yrs., 75 is good. Make sure their basking temp is 10 degrees higher, and that they can get completely dry on the dock. Both turtles should be able to fit on the dock together, so one doesn't 'hog' the basking times they both need. Try adding Tetra AquaSafe, follow the directions for the amount of actual gallons of water in your tank. How big is your tank? For each turtle, they should have 10 gallons of water per inch of shell length, not including the curve. So, for 2 turtles, double that. Just make sure the water level doesn't allow them a chance to climb out. The conditioner will help remove chlorine and chloramine and heavy metals. I add it when doing a complete tank clean, upon refill before I put the turtle back in. If you don't want to clean it again, since you just did, take the turtles out for a little while when you add the conditioner to let it cycle through the filter. It may be safe to leave them in, I don't know for sure. Maybe the best thing is to just empty the water, wipe it out with paper towels and refill it and add the conditioner.
Someone else may have another idea, if you want to wait for other's suggestions. But the chlorine and chloramine in the water definitely needs to be removed. Let us know how it goes!
