For newts, you shoould keep water between 60.8F and 69.8F.
Everything above 69.8F during a long time, and your newts will start to get healthy problems (Mycosis, digestive problems, stress, wiling to go outside water, etc...).
I have a female spanish ribbed newt since 8 years.
Every summer, my water temperature can go up to 82.4F !!! And every sumer, she has problems...Mycosis, stress, etc...
Last year she got gas in stomach and she was floating during some weeks. I went to a vet and it was cear that warm water was the cause.
One year later, she still has some floating issues sometimes.
So keep the water cold !