It has been nice and hot here in the uk!
You could get a fan to aim across the water or some aquarium fans that attach to the lid which could take it down abit.
I never found ice cubes worked that well and chillers are usually over the hundred pound mark which i didnt feel i could justify seeing as though the heat never lasts long here
I personally use a portable air conditioning unit for the room my axolotl is in when the warm weather comes which seems to work really well and cost around seventy pounds on ebay.
Hope that has given you some ideas.