Canister Filter Without Power Troubles

[Schmorty]

Well I done did goofed, forgetting to plug my canister filter back in after a water change, making it go anoxic for over a week. I thought I'd share my experience in case anyone else runs into the same or similar problem. I'll explain what happened, what I did to get out of it, and what I'd recommend for anyone with canister filters to do to prevent this. I'm not here to litigate whether or not canister filters are good or bad. This situation was 100% user error and can be easily avoided.

Background:

The aquarium in question is a 40 gallon breeder with a Fluval 206 canister filter with spray bar and intake sponge, as well as three sponge filters for additional flow and surface agitation. This is my fish-for-profit tank and is HEAVILY stocked with guppies and bristlenose plecos. I do water changes about once or twice a week and have a dense growth of hornwort and pothos to help me with water quality. It's a utilitarian tank, not a display tank, and I don't bat an eye when the water goes cloudy as long as the fish look healthy.

The Event:

I start my water change. As a pump withdraws water, I go underneath to unplug the canister filter, and I find that it's already unplugged. To make sure I'm not just having a forgetful episode, I feel the side of the canister filter to see if it's still warm; it's cold. I recall that the last water change I did was 8 days prior. Fortunately, I already know what that meant for the state of the canister filter.

The Problem:

Beneficial bacteria in your filters need oxygen from the water to process ammonia and nitrite. When you cut the flow of oxygenated water to them, they die after a few hours. Leaving your canister without water flow for a few hours won't kill your colony, but once you start looking at days without flow, there will be no oxygen left in the enclosed system. I knew that after 8 days, all beneficial bacteria in there would be dead. It'd be no use to plug this filter back in.

I also knew that between all the fish waste trapped in the sponges in the canister, the now-dead snails that lived in the filter, and the dead beneficial bacteria and the anoxic conditions, it was highly likely I had a strong colony of anaerobic bacteria going in there, feasting on rotting organic material. I have a degree in civil engineering, and my senior design project was building a small scale anaerobic digester to process solid organic waste into useable methane. It was a fun but stinky project, and an experience that really helped me deal with this situation. I knew that the canister filter was now full of dissolved hydrogen sulfide gas (aka sewer gas) and other nasties. I definitely didn't want to plug the filter back in and have it dump that gas and decaying organic matter into my money-making aquarium.

The Solution I Used:

I disconnected the 206 from its hoses. It's really nice that Fluval's canister design makes this easy. Already I could smell the hydrogen sulfide gas from the filter. I then took a bucket, placed it underneath the detached hoses, and opened up the shutoff valve to back-siphon all the stagnant water out if the hoses. I did this until the water ran clear. This water also stunk of hydrogen sulfide.

I started to attempt to clean the filter indoors....that was a very bad idea. That gas will stink up your home, make you want to puke, and it's very hard to dissipate. I've smelled open sewer manholes and wastewater treatment plants that were more pleasant. My advice is just take it outside asap. I'll post a follow up on how I cleaned up the filter and dissipated the gas from my home if people are interested.

My Recommendations For Prevention:

1. Place your canister filter on a Kasa Wifi Timer. Schedule an "on" to recur every night at 1 am (or whatever works for you so it doesn't kick on while you're in the middle of working on the tank). That way, when you change water and turn it off, you can hit a button on your phone. If you forget to turn it back on, the Kasa will always kick it on at the time you set and you're not looking at days without power and flow.

2. If you're experiencing a  prolonged power outage, take your canister filter media out and either place it in your tank or a bucket of water to keep it from experiencing anoxic conditions.

3. If you do notice your filter has been without power for a long while, don't immediately restart it. Assess the state of its contents (your nose will tell you if it's as bad as mine got).

4. Redundancy in your filter systems can save you headaches. My 300+guppies and 6 plecos appeared to have thrived despite the big canister filter being out of commission for 8 days. The sponge filters and plants in the tank kept it so I only had a small .25 ppm ammonia spike as opposed to something catastrophic. It also kept me from noticing that there even was a problem so there is that to consider.

 

[lefty o]

to prevent issues with filtration etc, i have each tank on a power strip. everything for that tank is plugged into the strip. doing maintenance, i turn off the switch on the strip. when done, hard to forget as the lights are plugged into the strip. if the lights dont come on, hmm turn the strip on. doesnt help for power outages, but for user error, put it on a strip.

[Schmorty]

On 7/24/2021 at 3:04 PM, lefty o said:

to prevent issues with filtration etc, i have each tank on a power strip. everything for that tank is plugged into the strip. doing maintenance, i turn off the switch on the strip. when done, hard to forget as the lights are plugged into the strip. if the lights dont come on, hmm turn the strip on. doesnt help for power outages, but for user error, put it on a strip.

This is a good method, and I'll do the same thing as well depending on the situation. I used to hate doing this because it would throw off any mechanical timers, but now that's a moot point with a wifi timer on the lights. I don't always do this because I leave the lights on so I can see better when trimming plants and I leave the air pumps on to make cleaning the sponge filters easier. But, @lefty o has the simplest solution for preventing the mistake I made.