Wait, if the internet goes down, or just the router? I'm sure I'm not the only one whose ISP goes down at least once every few months for several hours. Even if it's just wifi, I don't want to worry about my tank overheating/flooding if my router gets unplugged. Human error (me cleaning under my desk and disturbing it) scares me more than mechanical failure, although both are going to happen to my router.
That's a silly comparison. My cell phone can be off for a few hours without me dying. Heck, I go days in the woods without cell service.
A short time without electricity (especially if your powerheads have backups) isn't a major concern. A tank might survive 2 hours without power. It won't survive 2 hours of the heater being stuck on. It won't survive being dosed a full jug of alk. My floors won't survive my ATO being on for 2 hours. Failing "on" is worse than failing "off"
There are things you can do to your Hydros environment to add additional redundancies around wifi/networking. Here are a few options, not saying these are required but if you want added protection it doesnt hurt:
Local network redundancy
1) Run a wired access point off your main router with the same SSID as your main router. Put this on a separate circuit/outlet than your router. If your router, or the AP goes down for some odd chance, your Hydros will automatically switch over and your local devices (wifi outlets, and Controls) will remain connected and communicating (regardless if your internet is out). You can find wired AP's for less than $50.
System redundancy
2) if you add multiple Control units in a collective, you gain redundancy to your wifi network. One device always remains as the master and others as slaves. All devices in a collective run the same config/programming, so if your master somehow goes out to lunch or dies, a slave device will become a master and tell your wifi outlets what to do. You can set an outlet to a fallback state if a sensor isnt available (for example the temp sensor was on the main device that died), so that you can force an output to OFF or ON if this situation occurs.
Less about redundancy but more about flexibility
3) you can take this a step further and actually actually connect devices in your collective to different SSIDs as long as they reside on the same LAN. So if you setup multiple wired access points with independent names, you can have the master connect to one, and slaves connect to others. The only gotcha in this situation is that WiFi outlets can only be paired to a single SSID (during pairing, which ever SSID the MASTER collective device is connected to, is what the wifi outlet will use). This situation is more handy in cases where you have a large setup that spans a great distance.
I actually have my setup this way since I have a fish room with hydros devices on a dedicated wired AP with its own SSID for hydros only, and then more Hydros devices in my basement that can't reach the fish room SSID reliability so I have a second dedicated wired AP in that area for those. I have been running this system hard like this for months and have had no issue but planning on adding redundant SSID APs in the fish room just incase. Long term plan is to move over all system critical devices (heaters, pumps, ato) to the wired power bar coming out, but for now I have been running all devices off 8 wifi power bars with no failures or issues.
That being said back to the heater or ATO situation you talk about. To really failsafe your setup you should use a secondary heater controller if you use a wifi outlet, and ATOs should be connected to the Drive port on the device. Either using a relay or a 12V Hydros pump. Or you can do what I did for one of my tanks, I ran my ATO pump in my basement with a single wifi outlet, then at the tank side I put a Hydros Liquid Solenoid inline with the ATO hose that directly connects to the drive port. The wifi outlet and solenoid are programmed to be on/off together, so if for some reason the wifi outlet did get stuck on due to a router issue, the solenoid at the tank side would act as my direct wired fail safe. You could do the same locally if you wanted the protection.
