External aquarium heater

Step 3 Asembling part1

At first of all I've cut off mains plug from thermostat 100W aquarium heater,

then Set up temperature at 26-27C and put some sealant on thermostat knob and around seal (because when the filter is working on pipe outlet is slight pressure)

Hint: Even if you'll setup the heater to 27C, temperature inside tank will be 1-2 degree higher

Then I've drilled hole in the lid of inline water filter (CO2 mixer ;-)), put the heater cable trough the hole and filled hole by silicone sealant from both sides (that was the trickiest part of the job).

Now was time to secure position of the heater. I've used cable ties and some plastic washers to keep the distance from outlet pipe (see Warning!).

On the other side of outlet pipe I've stuck in thermometer the same way, just in case to control the temperature inside mixer (but this is optional really. I had already unwanted thermometer lying around, which has been replaced by electronic one).

Then I screwed in the bottom transparent part of water filter, and check heater position (see Warning!).
The original heater has been cut off (or you can solder off from PCB inside Thermostat) from external thermostat, and I've connected cable from new heater in place.

Warning: Heater (in fact only heating part see picture) must be completely isolated by water from any plastic elements inside housing, otherwise will melt down the plastic and even worse finally might crack itself, water + electricity... not good combination.