White Mold in Fish Tanks

Question
I have had a problem with fast growing white mold in my fish filters for over a year now.  I will clean the tank and within 2 week have the white mold all over my filter cartridges.  Looks like the same mold you would have growing on food in the fridge but without the black or brown spots.  It doesnt seem to have an effect on the fish but it cant be to healthy.  I keep my tank clean with regular water changes and I have even cut down feeding the 2 plecos I have in each tank to about 3 times a week.  Nothing will stop it.  What could be causing this?  Thanks!

Answer
Weatherednboston,                                            Do you have wood in your aquarium. Sometimes that can cause it. If you do take it out. Do you have well or city water. If you have city it may be caused by the chemicals they use to soften the water. Which means you have to use reverse osmosis and replace some of your water from another source like bottled water. I would add some aquarium salt. 1 tablespoon per 5 gallons it may help. I hope this helps, if it doesn't direct your question to expert chris robbins.... Good Luck, Tina