A little story to tell, I recently moved house (well not that recently, 2 years ago) in this new house the only place to put my fish tank is very near a radiator. now to cut a story short my little fellas got cooked, being near a radiator caused my aquarium heater to go haywire. i think because the radiator heats one side of the tank and that warm water wasn’t moving in sufficient enough amount towards the heater temp sensor. so the heater was heating fully the other side of the tank and the combination was tipping the water at its hottest at just over 30 deg C and my little fellas just gave up, i think mainly due to the varied temperature peaks and troughs during the day of over 7-8 deg C.
My fish tank had been sitting there empty since then whilst i was mourning the loss…or being lazy…you choose. i choose the former 
so this fortnight or so ago i resurrected the tank, and i also purchased another heater just in case the old heater was faulty and i thought i would use a Fibaro Universal Sensor with a DS18B20 waterproof temp sensor to track the temp of the tank. and i let it run for a few days and i could see the same wildly fluctuating temp variations of 7-8 deg C which is really bad for tropical fish. so thinking on i thought why not ST pimp my fishtank to better manage the heating and also automate some functions… so the end result is i am using 4 DS18B20 waterproof sensors daisy-chained off the Fibaro UBS which are placed in approx every quarter of the 6’ tank. I take an average of all the sensors to ascertain the tank temperature.
the heater is plugged into a ST zigbee plug (thought would be safer than Zwave as i do get the occasional misfire with zwave (i.e ST sends the command to switch of, but this sometimes is not processed due to Mesh instability, fixed by Zwave repair…usually happens after adding a new device)
anyway ST switches on the Heater when the average Tank Temp hits 23 deg or below and the heater plug switches off when it hits 25 deg C or above, this leaves a 2 deg C Temp Variation, which is still good.
As a Failsafe i also turn on the house central heating if the tank temp heat drops below 22 deg C and turn off the house Central heating if the tank Temp Hits 26 deg C. i also send notifications if any of these threshold are hit…I also send SMS Notifications via Openhab using my routers cellular backup circuit if the Internet and/or hub are down, this ST backup piece was important to me as Fish arent cheap.
What i have found is that if i or the family are in the house and the heating is on, the tank heater rarely if ever comes on. which is great as this amounts to keeping Tropical fish with no heating costs.
I also have a cheapo Everspring Plug i bought from Amazon for £28 which i plugged the tank light into…this is controlled by a timed rules machine rule. and today i have just put in a 5ft RGB Combined Strip Light and air block on the bottom of the tank which i hacked to pieces and replaced the controller with a Fibaro RGBW controller. this BTW looks awesome for mood lighting rather than a tank that isn’t lit up when the main tank light isn’t on (which is only on 3 hrs per day to limit Algea growth), the blue, Purple and Red colours look especially good…i’m just trying to figure out what colours of light still encourage Algae growth and which inhibit it, so maybe i can choose a light colour to display for extended periods to make the tank look good but still limit the algae growth.
Now to see how long the little blighters last, just picked up the first batch today and they are making themselves at home. we will see what the reliability is
anyway just though i would share my latest project i have been working on.
