My over-engineered inline heater/controller

[DUctapemaster]

So, a couple of weeks ago I noticed the 300W heater that came with my 90 gallon craigslist tank was stuck on, with the water being around 90. Good thing nothing was in the tank...I was doing a leak test a few days beforehand and got lazy and didn't dump the tank out.

So, being an engineer, I designed a DIY inline heater system which I just completed today. Of course, a simple PVC tube with a heater in it wouldn't satisfy my engineering gene, so I made things a little more complicated.

I haven't had great luck with heaters heating to the temperature I set on the dial, so I opted to spend a bit of money and get a PID controller off of ebay. I got the controller, 6' thermcouple, and a solid state relay for $38 shipped. Much less than making one myself!

The thermocouple is attached right near the outflow of my canister, so it senses the water temperature from the side of the tank opposite the outflow. From there, the water flows into the main heating pipe where a 300W Eheim Jager heater resides (set to maximum, so it will always be on when power is applied). From there, the water flows into a T joint, off of which the main outflow to the tank is piped through a valve, and a hose bib is attached for water changes/water fills.

All the electronics reside in a grey box next to the heater assembly.

After I realized my old heater was bad, I considered a Hydor inline, but from the reviews I have read they are not very reliable (especially considering the $50 price tag!), and people recommend hooking up an external temperature controller for safety which just adds to the cost.

So, for approximately the same cost as a Hydor inline 300W heater and an external heater controller, I was able to put together this system. It is considerably larger, but I have full confidence that it will work, plus the drain/fill attachment is an added bonus.

Total cost of the system was around $100. PID controller was $38, heater was $27, PVC/fittings were around $25 (valves are expensive!), plus miscellaneous screws and the wood I mounted it on - $10.

I can give more detailed instructions if anyone else is interested in building something similar!

Credit to this thread for the idea: http://www.plantedtank.net/forums/sh...ad.php?t=36257