Fungus in aquarium filter and in tank

Question
QUESTION: Hi, I have a 29 gallon fresh water fish tank with angel fish, bala sharks, and black skirts. I have had it for 2 years now and have never had a problem until now. There is a fungus looking white/grey substance that has started growing in my filter. It's started to spread to the glass below it. It is not in the water just above it where water touches. Also there is a thin film of clear stuff that is on top of all of the water. It's kind of slimy. I've tried to scoop it out and clean the filter a couple times but it keeps growing back. This started happening a few days after I used an old tank brush to clean the inside walls of my tank. I did a water change after scraping of all the green stuff. Also, I've never owned a gravel vacuum, although I've done water changes. I decided to buy one and used it to see if it would help but it still grew back. I keep the temperature at 78 or 80 degrees. The pH is at 7.0, ammonia was 0, nitrite was a little high but I don't remember the number (in the past it's always been at zero), and the nitrate was at 40 I think. None of my fish show any signs of disease or anything wrong with them. I don't know what this is, and therefore don't know how to get rid of it. A lady at petsmart said it was normal to have this mold looking stuff in your filter and that it's in all of theirs and they just wipe it off once a week.... I think she's crazy. Do you by chance know what this is and how to get rid of it?

ANSWER: Hi Stephanie,
 You should always use a gravel siphon when doing a water change.  

 When you say a "fungus", is it fluffy or is it just algae (it would be brownish more than white or grey)?  If it is fluffy (i.e., a fungus) it typically grows on rotting food.  Despite what your pet store person says, that is not normal and it is not good.  Is there uneaten food in the tank?  If so, you need to feed less.  Never give fish food "to eat later".  Only give them food that they will eat right away.  

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


---------- FOLLOW-UP ----------

QUESTION: Thanks. It's definately fluffy. I'm pretty sure it's not algae. I don't think feeding them less will stop it from growing, but maybe could've prvented it. I think I need to kill it. Do you know how to get rid of it?

Answer
Hi Stephanie,
  You can't "get rid of it" by putting some chemical in the tank or something like that. All you can do is to not put in excess food, and properly use an aquarium vaccuum when you do your weekly 25% water change. If you do those things, it will gradually go away.

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>