fungus?

Question
Hello,
I work for a pet store and I have a customer that I have been trying to help
but with no luck.  He has what seems to be a fungus growing in his tank but
not affecting the fish.  He has tried medication to treat fungus, but it did not
keep it away.  He has entirely cleaned out the gravel in the tank and it
reappeared in about a week.  It has a cottony texture to it and is about an
inch long.  He does consistent gravel vacuuming and yet his ammonia level is
still 8.0.  I have given him some zeolite crystals to help with the ammonia and
he is going to do another water change.  His PH is 6.0, nitrite is 0.25, nitrate
is 10.  It is a 75gal tank with semi-aggressive fish.  My last resort is to get
him to buy a new filter.  The one he has is an off store brand.  Any help that
you could give would be greatly appreciated.
Thanks!

Answer
Hi Kailyn;

It sounds like rotting food or fish waste infected by bacteria. Tell him to vacuum the stuff out and don't feed the fish for a couple of days. When he feeds again, the fish should eat every bit of food within 5 minutes. Any leftovers should be removed. Rotting food can very quickly be infected by saprolegnia fungus, which sounds like what it is to me. If he could get a digital photo of it and you could attach it to a followup I could take a look.

If his tank seems overcrowded he may need an additional filter but if his is working fine there's probably nothing wrong with it. Off-brands can be just as good as a name-brand. Take a look at what the capacity is for the filter he has now and see if it's rated for at least a 75 gallon. If you aren't sure, give me the details and I can find out.

I would also re-test the water for ammonia using a different type of kit. If he has ever used water conditioners with an ammonia binder (Ammo-Lock, AmQuell, etc.), the test result can give you a false reading. You need an ammonia tester that does not use "nessler reagent". With nessler as the testing chemical, it can say there is ammonia when it is already bound and rendered non-toxic by the Ammo-lock or other ammonia product.

Good luck and let me know if I can help further...

At Your Service;
Chris Robbins