Fungus growth in aquarium water

Question
What is safe to add to aquarium water to stop the growth of what appears to be fungus?  The fancy tailed guppies seem to be doing well, but small amounts of fungus keep reappearing since my filter pump failed.  The filter pump was replaced, filter bag is changed often, all artificial plants removed and thoroughly cleaned (many were discarded)and tank water changed 50% each 2 weeks. There are no signs of disease on any of the fish - yet. I would appreciate any help you might offer. Thanks!

Answer
Hi Cindy
Usually when there's fungus growing on something in the tank, it's left over food or waste or something that died and is rotting, that's what the fungus is growing on.  Since your filter stopped, that's most likely why it happened.

You're best bet is to use a gravel vacuum, and vacuum the substrate really good.  Also along with that, doing at least 25% water changes weekly will help.  Don't overfeed the fish, so there's nothing left over to rot/turn fungusy.  I'd stay away from any chemicals, the least amount you can use the better off the fish are.  

Another thing you might be seeing, the beneficial bacteria that was in the tank prior may have died off from the filter not working.  If you're seeing cobweb type things, that could be the beneficial bacteria re-growing.  The best way to check this is with a test kit, test the ammonia, nitrites, and nitrates.  In a cycled tank, ammonia and nitrites should be 0 ppm, and nitrates kept under 20 ppm.  If you're tank is going through another cycle process, you'll see ammonia and/or nitrites present.  Also, here's a link that explains the cycle process if you're not familiar with it, it's the first article:

http://freshaquarium.about.com/od/startupcycle/Step_5_The_Cycle.htm

Not sure what type of filter you're using, if it's one of those hang on the back filters, you don't want to be replacing out the filter pad that often.  In fact, maybe once a month just rinse it out in a bucket with some tank water, and only remove and change it completely about every 3 months or so.  The reason is, most of the beneficial bacteria is living on the filter media, it also lives in the gravels, or any rocks or decorations, but you definitely shouldn't change it out that frequently.

If you don't have a test kit, I would recommend buying one to monitor those levels I mentioned above.  Good luck and hope that helps!

Christy