# Canister filters and power outages



## hp10BII (Apr 23, 2010)

FYI - Canisters are great for holding more bio media and silent operation, but a pain to service in a power outage, especially if you have several canisters in use. Just saying this because our power was out for about 5 hours this morning. From what this post is saying, if your canister filter is shut down like in a power outage and starved of oxygen, hydrogen sulfide can be produced which is toxic to fish. When the power goes back on, the hydrogen sulfide is pumped into your tank. Anybody ever had this problem?

https://www.monsterfishkeepers.com/...-fx5-become-toxic-without-power.309802/page-2


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## VElderton (Jun 3, 2015)

What is your set-up? If we knew that we could help provide a better answer to your question. 

I use to live in a more remote area and kept freshwater tanks where power often was down for hours at a time and never had any obvious problems when power returned. 

I think bacterial die off woiuld be more of an issue than hydrogen sulfide build up during short power outages. 

This recent bout of winter weather has got me thinking about UPS. I have thought about this for tech / data but maybe it's time to consider this for the fish room.


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## hp10BII (Apr 23, 2010)

Not really a question, just out of curiosity because I never had any sign of hydrogen sulfide issues either. From what I've read, it's a combination of bioload, organic build-up, etc. before you past the point of no return when anaerobic bacteria takes over aerobic bacteria and produces hydrogen sulfide. For one tank, I have 2 Eheim 2217's and an AC110 for a 125g. The other is an AC110 with an Eheim 2262 also on a 125g. My smaller tanks have either HOB's and/or sponge filters - that's easy to deal with in a power outage.

Here's another article filters/power outage:

Aquarium Maintenance: Surviving a Power Outage | Home Aquaria

I bought a UPS, it's still in the box...


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## sschlesier (Sep 16, 2016)

I'm no expert, but AFAIK Hydrogen Sulfide will result from anaerobic activity. The doubling time of anaerobes is days not hours, so it seem unlikely for Hydrogen Sulfide buildup to become an issue in a few hours. Loss of much of the aerobic organisms, and hence the inability to process Ammonia seems the most likely problem.


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