I have two Red-eared turtles (I was wrong in my former question about them being "trachemys scripta scripta": they are trachemys scripta elegans; don't know whether it makes a significant difference in the question I have now, but just to clarify the readers), in my aquarium (50x30x6cm water, some rocks and dry stuff, and a warmer). I clean my aquarium once a week, replacing the water, and everyday I add two drops of methylene blue to the aquarium (and also feed them, once a day).
The warmer got broken (don't know why, nor how - I just saw the turtles were less active today, and the first thing I checked was the water warmer and temperature: the warmer was like scratched in the surrounding glass). I don't know when did it broke, but was between yesterday night (perhaps 10pm, or today after 00hs) and today morning (before 8:30am). I disconnected it when I saw it scratched. At 13:00hs here, I'm planning to buy a new one. Current environmental temperature (11:30hs now) is 21°C.
Is it somehow dangerous for the turtles the current situation? Should I take additional* cares/checks on the turtles?
(* besides running as fast as I can to buy and install a new warmer)