Put sensors in place
How it's done
After you are sure that electronic is working fine, put sensors in their place.
Fix float switches in tank. Insert stone bubbler and water pump in tank. Make holes on tank cap for air and water pipes.
Insert waterproof temperature sensor inside tank.
Insert float switch in upper pipe tank (like on picture).
Make hole for water pump pipe and fix it in place.
Make sure that light sensor is on surface where sun light can reach it.