Surface film and other annoyances...

Someone asked what's the thing that I hate the most about botanical-style aquariums. I had to give it a lot of thought, but I think I found it.

I hate surface film.

What exactly is "surface film", and why is Scott so obsessed about the stuff?

Surface film is a sort of "aquarium vernacular" for "surface active compounds"- a scum of organics, microorganisms, proteins, and good old fashioned "dirt", among other things- which accumulates on the surface of the aquarium. Large organic molecules are not generally very soluble. They tend to adhere to all sorts of surfaces- the water/air interface being one such place that is immediately "in our faces" and is rather objectionable in appearance!

In some instances ,it's unavoidable- you know, like my ultra-small "urban Igapo" tanks, which typically run without any filters.


However, in larger, lightly-filtered tanks, this stuff becomes more of an issue to me.

The air/water interface is the "boundary" (technically called the "surface micro layer" by scientists) where all exchange occurs between the atmosphere and the aquatic environment. Interestingly, the The chemical, physical, and biological properties of the SML can differ significantly from the water just a few centimeters beneath the surface! 

In Nature, the concentration of these surface compounds depends on the source of the nutrients, as well as weather, like rain and wind. These organic compounds on the surface impact the the very physical and light admittance properties on the air/water interface. 

As aquarists, the biggest concern is that the surface film can interfere with gas exchange. Oh, and it looks like shit, right? 

Yeah, always seems to come back to aesthetics over almost everything, huh?

Well, maybe...

You see this stuff in almost every aquarium with a varying degree of annoyance, and it's just something that we "deal with", right?  Yeah, pretty much. And the reality is that it's likely not a huge deal for many hobbyists or their tanks. I mean, it's been something we've seen in tanks for over a century...and in the days before aquarium filters arrived, it was not an issue we heard mice about. And when we had goldfish in bowls as kids, it never seemed to bother us (so many other things about a goldfish in a bowl should have, right?)

Yet it's there. And to some of us, it's really ugly!

How do you deal with it?

Well, there are a few ways.

First, you can employ an aquarium which incorporates an overflow weir, which pulls water from the surface into the filter or filter chamber. That's what I am a huge fan of reef-ready aquariums, or many of the so-called "all-in-one" tanks, which draw water from the surface into the filter. This is a convenient way of pulling the most organic-rich water in the aquarium right into the filter.

The other alternative is to employ a surface skimming device.

Without me embarrassing myself while attempting to describe the way these things work, let's just say that they a device which employs an intake at the water surface, a small body, with an internal pump to draw in the water. These little gadgets do a remarkably good job at removing the aforementioned surface film. Now, I admit, they kind of look, well- shitty- but they are relatively easy to hide in most tanks, and get the job done!

If you're like me, and you hate looking at mechanical devices in your tanks, you either:  1) learn to live with it and appreciate the nice clean water surface, 2) hide the damn thing with clever hardscape, or 3) deal with the fucking surface film. 

Oh, before I wrap up this short, but epic treatise on one of my personal aquarium "pet peeves", I'd be remiss if I didn't mention my fave of the bunch..

The "Porsche" of surface skimmers, the Tunze Comline 3161. A beast of a device, it's a little thing, too (4.5” x 2.4” x 6.9”), and fits nicely into most small tanks, including the aggravating ADA 60F (which is only like 7" tall).

Like everything Tunze makes, it's seriously engineered, with innovative features and a powerful silent pump. Tunze makes reef-keeping gear, which means that it's designed for harsh environments and doesn't suck. So yeah, it's more expensive than the inexpensive knock of crap you find on Amazon or whatever, but it actually works. A good trade-off IMHO. This thing could easily serve as the sole filter/surface skimmer in a nano-sized tank, perhaps even one approaching 15 U.S. gallons (60L).

If you can hide it, it's worth every penny.

Again, the idea of surface film is just something that we have to deal with in the botanical-style aquarium.  And to many of you, it's no biggie. A non-issue, really. However, with a lot of decomposing leaves, botanicals, and other materials, it's probable that at some point, you're going to encounter stuff like this.  Sure, you can deal with the stuff with good surface agitation, too...But it always seems to accumulate in some far corner of the tank.

Yeah, surface agitation. Good!


So, you asked...I'm sharing. That's my aggravation...served up for your consideration!

Stay unfazed. Stay calm. Stay happy. Stay innovative. Stay resourceful...

And Stay Wet.


Scott Fellman
Tannin Aquatics 


Scott Fellman
Scott Fellman


4 Responses

Scott Fellman
Scott Fellman

November 08, 2020

Ahh, Nikolay, as usual, you get me thinking and curious. Would love to discuss this more with you at some point

Nikolay Kraltchev
Nikolay Kraltchev

November 08, 2020

Surface film is natural to a point. When the tank truly matures it disappears and the water gets the established tank shimmer/appearance and exceptional clarity. The film it disappears completely from one day to another when the biofilter matures properly. When using a special kind of activated carbon (not sure you will like posting a brand name here) that happens predictably between week 3 and 4. In addition to the water staying completely invisible up to this point. The 3-4 week transition has to do with that carbon turning into a biomedia with specific characteristics that support the microbes. So yes – one can have both a natural and surface-film-free tank. Which is an indication of a properly developed and happy biofilter.

Scott Fellman
Scott Fellman

November 06, 2020

LOL, you’re right! It IS natural…And I SHOULD embrace it…But people asked, so I"m sharing my feelings on this stuff… Crazy, huh? And I suppose that I could make the argument that, in a closed aquarium, surface film is an impediment to gas exchange and a possible problem…Okay, I’ll make that argument…but the bottom line is that I HATE IT!

Yeah, I guess that’s ONE mental shift I haven’t made just yet, lol




November 05, 2020

Hey wait a minute, if you’re convincing people that decaying leaves and detritus are beautiful, why do you say surface film is ugly? It’s part of nature and if you have a problem with it, you may need a mental change in this regard. You will save on skimmers and calm your heart. ;) Regards, have a nice day!

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