GTR73 Posted January 17, 2006 Share Posted January 17, 2006 I've always been puzzled as to how bacteria colonies would thrive in an external filter given that both nitrosomonas and nitrobacter bacteria are aerobic (requiring an adequate supply of oxygen to sustain its life cycle). I've been told don't use Bio balls in a canister because they're not optimal for that environment and better in a wet/dry filter or mini reef. Fair enough. So I've always used ceramic noodles, and my external canisters work fine. But how does sufficient oxygen get into the sealed environment of the canister, given that we all go to great efforts to remove air pockets in its system to "prime" the filter? Externals seem to provide adequate biological support, but how? Maybe I'm thinking about it too much, but if anyone can offer advice it'd be appreciated. Link to comment Share on other sites More sharing options...
hardb0iled Posted January 17, 2006 Share Posted January 17, 2006 The O2 is already dissolved in the water, its what the fish breath. You can increase the dissolved O2 content by adding surface movement in your tank. Trickle filters work well because there is LOTS of water contact with the air in the filter due to the open design of the bio balls and the water trickling down through them, this increases the oxygenation of the water and hence the bacteria thrive. But bio balls dont have as much surface area as canister media so it doesnt perform as well fully submerged where its 'open' design is not an advantage. Link to comment Share on other sites More sharing options...
Ant Posted January 18, 2006 Share Posted January 18, 2006 I've always wondered if temperature can affect the efficiency of a cannister filter given that O2 levels are lower in higher temperatures. My thoughts are that 3 or 4 degrees probably doesn't make much difference. Not to hijack your post, but it is kinda related. Anthony Link to comment Share on other sites More sharing options...
GTR73 Posted January 18, 2006 Author Share Posted January 18, 2006 . . . and this is exactly the sort of stuff I'm thinking of as well Ant, given that I live in stinkin hot Brisbane. I've asked the question because I soon plan on upgrading the filters on my 4'x18"x18" display tank, replacing the 900L/hr external and 1400L/hr internal canister with a 1850L/hr external that has an approx 3L capacity. I was hoping to use the bigger external by itself and get rid of the internal canister, maybe just leaving a smaller powerhead in the tank for air and waterflow. Link to comment Share on other sites More sharing options...
Ash Posted January 18, 2006 Share Posted January 18, 2006 Sorry if this is a dumb question/statement - but wouldn't your fish cark it before the oxygen levels got so low as to harm the bacteria? Link to comment Share on other sites More sharing options...
CThompson Posted January 19, 2006 Share Posted January 19, 2006 Your fish are alive, your bacteria will be fine. As mentioned warmer water holds less O2, but if your fish are fine, your bacteria are fine. An issue will come about with a power stoppage as there will be no water flowing through the canister to bring in the oxygen. A rule of thumb I run by is that in cases like this the bacteria will start to die in about an hour. There are things you can do here, such as open the canister up and remove the bio media (hopefully it's in a bag) and providing it stays damp (with fish water), it is better out than in. You could also go to the trouble of setting up a UPS to power the filter through. Craig Link to comment Share on other sites More sharing options...
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