Baffled Too Much?

So,
I’m working on a 5 gallon glass top fin tank, an upgrade for my betta. After plugging it in the pump, even on the lowest setting, I know will for sure be to strong when I move him. I have a fluval pre filter sponge on the outflow (outflow piece is similar to the fluval specs) and I poked some holes in the air pump tube with a push pin. There is like zero surface agitation in the display tank, will this be a problem?

 

I should also mention I’m about halfway through my fish less cycle and there has been a slight film on the surface of the water, is this because there is no surface movement?

 

you want a tiny bit of surface movement

 

I’m just afraid he will get smacked around, he really doesn’t do well with current.

 

a gentle flow of water hitting the surface shouldn't smack him around honestly.

 

You would think, but I’m my current I had to replace the filter because it was so bad.

 

Do you have a picture? I'm trying to understand what you are saying, because the way it seems is that there is no water hitting the surface at all. As long as there is some sort of current (if this is an internal filter) near the top of the tank, you should be fine.

 

With prefilter (1) and without (2)

 

Ok, now I get what you are saying, I think it should be fine so long as you keep up with water changes to keep the film at the surface at bay. The other thing you could do is find a way to make a big enough hole in the sponge so when the water comes out it hits the top of the water, but just slightly, up to you though, might be tricky to do.

 

My biggest concern was that the sponge would block the water to much, because there is no movement when I have it on.

 

That's why I said modify the sponge

 

Should weekly water changes keep up with the film? Once the cycle is over I’ll start doing them.

 

I would think, but honestly it would depend on a few factors too. If that doesn't keep up with the film then just put a little hole in the sponge so the water can get through it the tiniest bit and that will help.

 

I was also concerned that poking holes in the pump tube would be baffling it to much. But I also only used a push pin, so the holes aren’t that big.

 

Do you have an air pump that is rated fairly low or is it pretty powerful?

 

It’s the one that came with the tank, that connects to the outflow nozzle in the pics. I think once I cut the sponge a little it will help.

 

You definitely need surface agitation. I had to replace 2 raggedy filters on my 5 gallon because there was hardly any flow or agitation. And the top of the water always had a film. I switched to a sponge filter and it was the best thing ever. Hardly any flow and the surface is never filmy. My short finned and long finned bettas swim great with this filter

 

You don't need surface agitation with bettas. They breathe at the surface and the level of C02 in the water isn't important. No movement of the surface will create a layer of bio film on the water, but this is not dangerous or an issue, it's just unsightly and can be removed if desired.
Filters in betta tanks should be very gentle and they do not have to filter a lot of water since the bio load is so low. Several water changes should also be performed each week (filter or no filter) and therefore the parameters will never really rise above 0 anyway.
It is way more important that the water flow from the filter doesn't stress out your betta than trying to create surface agitation in a tank housing a fish that doesn't even need it.