I got my new HOB today. Is it silly to run it side by side with my current one while the bacteria develop?

[KyleKVK]

I’m switching from a Tetra Whisper 20 to a Seachem Tidal 55.

The Tetra is cycled but only has sponges in it. The Tidal has a weird shaped media basket so I can’t just chuck my sponge in there. 
 

I’m running them together for a week or two so that beneficial bacteria can grow in there. Is that silly or am I right in thinking that’s a good idea so I don’t disrupt my cycle?

[lefty o]

seems like a solid plan to me. better safe than sorry.

[Andy's Fish Den]

I don't see why you couldn't as long as you have enough room on the side of the tank 

[Frost]

That's what I would do as long as I had the power outlets available for it. I don't know what fish you keep but I'd keep an eye on the flow from two filters and adjust accordingly, but it's not something I would worry excessively about.

For example if you have a betta I'd turn the flow down because they're notoriously poor swimmers but I wouldn't worry about the increased flow for a whole lot else

[Coronal Mass Ejection Carl]

The bacteria aren't limited by surface area. In fact, it only takes a small amount of surface area to support a large amount of fish. Adding a 2nd filter to your tank may not do anything because the bacteria don't need to grow there especially with no increase in bioload.

Your new tank may cycle a little faster though.

[JettsPapa]

Not only do I think it's not silly to run both, but I think you absolutely should run both.

[Jollypop4321]

Well I run two  hang on the back filters inn my 20 long.   Actually three f you count the sponge filter.   
The reason is I wanted the extra filtering in the beginning was the wood I added to the tank made the water amber colored. I added it to help with removing it quicker.   I just never took out the extra filter.  Doesn’t seem to harm the fish or plants.  Can’t say there is any benefit from it either. 
As mentioned earlier the live bacteria lives on all the plants and hard scapes in your tank, so it is not crucial for your filter media to be fully loaded right now.  As long as you have not cleaned the gravel or hard scapes at the same time.  
 

[FrozenFins]

I run two HOB filters in my community tank, one for my QT tank and the other as the "main" filter. works fine for me.

[Ryan F]

I'll chime in and say that running both filters concurrently for a few weeks is absolutely a great idea.

Another option would be to take the sponges out of the old filter and squeeze them out into a bucket of tank water with the new filters media in the bucket. Create a murky mess in the bucket with all the filter media. If you can then let the new filter run in the bucket so it collects everything shed by the old filter, then install it on the tank.