HOB or 2 HOB

[Dino Tamer]

Hi everyone! I recently have seen more and more tanks with two Hang on back filters instead of one, and I was wondering if there is a significant difference between having only one and having two? And is there pros and cons to having 2?

[Nate s]

Back in the day I put two smaller ones on my 55 gallon to have the same filtration as a bigger one without a bunch of flow 

[Kalita]

Depends on the size of the tank and what's in it. Some fish like more flow and oxygen so that would be a case where I'd opt for 2 vs 1, especially if it's a long tank. I don't want any "dead zones." I like to ensure that nutrients are circulated throughout the whole tank.

Additionally, can have more beneficial bacteria with 2 HOBs vs 1 - that's helpful especially if you need to seed new tanks. Also less chance of accidentally crashing cycle if you alternate cleaning.
 

Edited April 30, 2021 by Kalita

[CHC Chris]

I always try to have at least two separate filters on my tanks. That allows me to more aggressively clean one while the other continues to operate. The MAIN reason, however, is simple for a fail-safe setup in case one filter fails. 

[CalmedByFish]

I think it was just last week that a filter zapped me. It was a small filter, so didn't carry much punch, but I learned a lesson. Although I won't get rid of high-watt items I already have, I'll by multiple of smaller power from now on. That way if something is releasing current into the water, it will be limited on how much. (If I understand right.)