If at all possible I try to keep the aquarium hardware out of sight in the aquarium. I want it look like a natural scene as much as possible. I don’t like to see heaters, probes, etc. I use black PVC, PVC fittings, and airline tubing inside the tank to make it blend in with the background. To hide the heaters, I decided to build in-line heaters. Basically, a heater and temperature probe inside a 2” ABS pipe put in-line with the filtration system. This would allow for efficient heating of the water and keep the heaters out of sight.
For this aquarium I figured that I would need about 600 watts of heating. I found these titanium heaters on Amazon, so I bought 2 – 300 watt heaters. These do not have thermostats in them, so you have to buy one separately or have some other way to control the temperature. I bought these because they didn’t have a thermostat built-in and I used my Apex Jr. Due to limited space behind the aquarium, I decided that two short ones would be better than one long one. I was hoping that they would thin enough that I could put them side by side inside the ABS pipe. Unfortunately, they were too fat with the rubber ends, so I decided to make two in-line heaters one for the filter intake side and one for the filter return side. That way they would be short enough to not interfere with other components.
**On a side note, after I bought these I thought that it might actually be better to have heaters with thermostats as a fail-safe. The thermostat would be set a little higher than the intended temperature of the aquarium, but not so high that it would kill the fish. This way if the main temperature controller failed, the fish wouldn’t be cooked. I thought a fail-safe was such a good idea that I ended up adding my own (add link to post).
I used cord repair kits to put the plug ends on the heater cords.
I keep the aquarium at 83 degrees. I’m able to keep the temperature within about 0.2 degrees.