Surface scum - solution

argnom

Guru Class Expert
May 24, 2009
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Montreal, Canada
Yeah! :D

The dreaded surface scum is no more! And it only took 24 hours. No new equipment, no finicky surface skimmer no powerhead. Just a couple of fish. I took a quick look in the forum and could find no post about what appears to be a great solution to a common problem so I though I would share my joy with you.

I was looking for a biological solution rather than a mechanical one for my tank and as I looked through many forums to find an answer, I found a post in another forum suggesting that mollies will "eat" the scum.

Well, this sounded so "funny" that I had to try it. Now, mollies are some of the most common fish you can find. How is it possible that my LFS did not suggest it instead of a surface skimmer?

So I purchased 2 female mollies and low and behold! It actually works. Within about 20mins, those 2 little mollies were "eating" the scum. Now, I'm not certain if they actually eat it or if it just annoys the hell out of them and they agitate the water to get rid of it, but as far as I can tell, they're eating it. They go to the surface of the water then open and close their mouths. At first I though they were gasping for air but as I looked closer, I noticed that the fish did not look panicked in any way, they were opening and closing their mouths until they had a little "ball" of scum accumulated and would swallow and swim away... After a while, they would even face the current so that they could get better access to the scum.

When they were done clearing the surface scum, they started to nibble on the little hair algae that I have in the tank.

I never liked those fish until now! Yeah for mollies!

Do I have 2 abnormal mollies or is this common knowledge and you're now all thinking that I'm a complete moron? :p
 

Gerryd

Plant Guru Team
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Sep 23, 2007
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Hi,

Your mollies seem like many others....Mollies pick at EVERYTHING and they do like to skim the surface. Their activity alone at the surface will help to break the scum up...

Mollies are GREAT fish, but not the smartest around :)

No one is laughing at you. Read some of MY posts/blunders/etc before you call yourself a moron lol
 

Tom Barr

Founder
Staff member
Administrator
Jan 23, 2005
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+1 if you can stand the fish.

Regards,
Tom Barr
 

Left C

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Sep 26, 2005
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Male Gold-Dust Sailfin Lyretail Molly

green_lyretail_male_molly.jpg
 

jonny_ftm

Guru Class Expert
Mar 5, 2009
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I don't think they will do the job for a long time. Once you'll begin feeding them they won't look at many other things, except, from time to time some algae (but don't expect them to resolve any algae issue, they only eat what they need, not much).

Feeding and adding fish will only worsen that problem in my expierience. Also, 2 female mollies is not a so "biological/natural way", they need males, they are prolific and not the best fish to keep with many others. Once you remove them, if the scum didn't come back earlier, you'll end up again with the scum.

Better find another way in my opinion. Often, ignoring it, despite the hidous aspect is a must. Having some surface movement "everywhere" helps, when it gets too dense, you can remove it with a reciepient before WC. In my case, it always ended by going by its own when the tank is stable and no more fish/excess feeding is added during that period. Also, fat products (frozen and live/fresh food)worsens it
 

shoggoth43

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Jan 15, 2009
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I have noticed the food connection as well. Glass worms especially in my case. Incredibly thick layer after only a couple of feedings. Surface agitation helps but not always. A surface skimmer seems the only surefire way.

-
S
 

Gerryd

Plant Guru Team
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I have temporary surface scum in both c02 and non-c02 tanks after feeding scrambled eggs to my fish.......goes away rather quickly....
 

shoggoth43

Lifetime Charter Member
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Jan 15, 2009
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And I just picture you holding breakfast over the tank... What? No bacon?!?! :D

-
S
 

jonny_ftm

Guru Class Expert
Mar 5, 2009
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Many factors actually play a role. In the nano DSM started tank, the surface scum formed despite the tank was without any living stock for months after immersion. Surface flow didn't help either here. I just waited, didn't change anything except removing the film with a recipient before WC. After few weeks it went away by its own. Now, the tank has shrimps + boraras brigittae that I feed every day + vegetables and some meat from time to time: it never came back

I suspect organic debris also play a big role. When the tank was immersed, after 4 months of DSM, too much organic matter was present on surface of soil.

This is only theory as the the film is hard to induce and hard to remove without a skimmer
 
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argnom

Guru Class Expert
May 24, 2009
109
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16
Montreal, Canada
Thanks for all the feedback. :)

Even if it is not a permanent solution as some have mentioned, for now, it seems to be working great. I'm not 100% certain that this problem is caused only by to food. Although I do feed frozen mosquito larvae to my fish since I was not able to convince my blue rams that flake is food. They'll go for it, but they spit it right out. Fussy eaters they are.

I had the same scum problem in another tank that has no critters in it. Things got better when I started dosing a little less iron in the water. I have read that the surface scum is a kind of bacteria that thrives in iron rich environments (for the white kind that breaks if you agitate, not for the green kind).

Jonny, I do not understand what you meant by "they need males". I do know that they are prolific, but they do not seem to be aggressive at all and they seem to be doing fine on their own. :p To boot, the other fish don't seem to mind them at all. All I have in the tank are a few golden tetras, a few otos and 2 blue rams whom got a little cranky when they saw their new thank partners, but they stopped bothering them.

The odd thing is that for now at least, they seem more interested by the algae and surface scum than fish food. I hope it stays that way.

Tom, I don't know... They're definitely not cichlids let me tell you that. I think my tetras are "smarter". You are right Gerry, they do seem to be dumb little fish. haha
 
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dbazuin

Guru Class Expert
Dec 30, 2009
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after I post this my lfs phoned the skimmers where delivered. So I went to them and get one. On the instruction the recommend to put in a bucket of aquarium water for the night. Tomorrow it goes in the tank.
 

jonny_ftm

Guru Class Expert
Mar 5, 2009
821
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If it's same as the chinese one I got from ebay (looks exactly identical), it has a so bad toxic plastic smell that I never put it in my tank (google for plastic china smell). Plastic looks also to be poor quality and won't last long in water before cracking
 

dbazuin

Guru Class Expert
Dec 30, 2009
156
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I installed it in the tank and it works fine. How it will holding in the long run is something we see in the future.
For now it does a good job.