hey well i have 2 axles about 9 months old i got them when they were 6 months old and about 2 inches long. they are now easily 5-6 inches long and are going good.
What size tank?
because of the hot weather the tank water seems to be getting really warm
how warm is "really warm"? excess heat can cause extreme stress in axos so that they succomb easily to opportunistic infections. ideally the tank should be no higher than 20-21 degrees C, but it must not exceed 24 or so.
any tips?
Look around at some of the temperature related threads here. many people use frozen bottles of water to help control the temperature, but some feel this causes fluctuations in the temperature that are worse than steady heat. the best low-tech solution seems to be running a fan over the surface of the water all the time, as well as moving the tank to the coolest area of your home (and possibly putting it on the floor.
i change the water every week
How much do you change? Hopefully not all. If too much water is being changed on a regular basis the tank may not be cycling properly which would also stress the axos.
Good luck, e