Hi mate,

I'm sure if you could encapsulate the DS18B20's in some form of heat shrink boot you could use this project to control heaters in up to 4 tanks, and with the DS1307 and a bit of adaptation program seasons with shortening / lengthening days to switch in those lights.

The version of the code I'm now working on is so far advanced than that listed here, but what is listed can be used as a base if you wish.