Floating Surface Scum Bits?

Question
Sounds like a Pirate Cereal brand? Nope.
Background:
TANK: 55 gal tank.2yr old Whisper Lite hanging tank filter rated for 50-70 gal.
FURNITURE: Normal aquarium rocks. 3 plastic plants. 1 Resin-esque statue head thingie.
CONDITIONING: ATI Stress Coat Marine, used for ALL water changes.
FOOD: Tetramin Flake, and 1/2 a algae chip at night.
POPULATION: 9 yr old pleco, and 6 neon tetras.

PROBLEM: The last few weeks I have been noticing an odd, flakey scum floating on the surface of the water. While I DO feed flake food, I am NOT overfeeding, as I am pretty anal about watching my guys eat and letting them eat it all up first before giving them any more. So I know its not that. My filter does have a moderate amount of mineral build up, but I still scrub it with a brush and if there is a permanent stain/line I don't worry about it too much.

STEPS TAKEN SO FAR:
-Completely dismantle all components and rinsed with hot tap water, and scrubbed with brushes, every stitch of everything. Dismantled all movable filter parts and cleaned similarly. Replaced all parts. Re-assembled the entire tank, started with new conditioned water. New filter floss etc. Ran tank 8 hours. Fine. Replaced population. 24 hours later, slight scum flakes returned. 8 hours later, CRAZY amount of flakey scum (looks like floating flake food but is not!) all over the surface. Not sinking down into the water, but always floating. NO cloudiness, only these crazy flakes of who-knows-what! Oh and 1 tetra is now dead. :o(

SECONDARY REMEDY:
Carried out 10% water change daily.
Did not touch filter, furniture, anything else in anyway.
Just siphoned it out, and siphoned it back in. (Siphon is not old, but neither is it new, and is in good repair).
The water changes seem to have solved the problem.

QUESTION: (Finally, huh?!) ;o)
Is it possible that mineral build up on a filter, can become loosened over time, (even though you are scrubbing on it still nothing else seems to come off of it) and make it necessary to just replace the whole filter, and be the cause of such a problem?

Thank you for taking the time to read this tome, I tried to include all of the pertinent info so as to shorten your time spent thinking about this.

Thank you for your time and consideration.

Michelle  

Answer
Hi Michelle,
I know what you are talking about and it is easy to fix.  Surface Scum can be due to anything.  Some fish foods contain the ingredients that cause it.  Like foods that contain fat or type of oils.  All you need to do is increase water agitation.  The water level of the tank must be lower than that of the HOB filter enough to where some a tad bit of splashing occurs.  All it is, is due to lack of water agitation.

The mineral build up happens with most aquarists and is not of a big concern.  It happens more rapidly in those who have hard water.  Majority of the cities have hard water due to metal pipes and etc.  Those with soft water rarely have this issue.  Soft water can be from wells, distilled water, or reverse osmosis water.
-Matt-