my tank water volume should be around 12g including IOS.
I was also thinking to supplement the iceprobe with my current 10cm fan if i decide to get it.
in fact I find room aircon with PC fan very effective for my nano
if room aircon can be programmed to on from 3pm to 9pm everyday, and PC fan keep running, then could be sufficient to keep the water cool for whole day though temp. may swing from 26 to 28 degree. .. electricity bill should be another $10 per month maybe
so for 3yrs, est. more than iceprobe lifespan, is $360 .. slightly more than iceprobe cost ...