Thanks for the input guys, the problem got much worse, so yesterday during the rainstorm here in Jersey, I decided to clean EVERTHING.
I had both coarse blue foam pad replacements for the canisters, and the soft white fleece pads as well.
I also removed all the filter hosing including the plastic intake tube, and plastic outlet tubes.
MAN!! All the tubing was loaded with limescale. I ran super hot water through each tube, limescale gunk came pouring out, I then ran hot water through each rubber hose same thing.
Because I had no brush I also filled each rubber hose with vinger, gave it a few pinches with vinger in hose, to remove lime, and flushed again.
Then I removed each canister filter, gently washed Substrat Pro and BioMax, washed canisters out, replaced blue-coarse-filter and white filter cloth fleece and the problem is gone.
The top filter tray on each canister was LOADED with those limescale chunks that were on the filter lines.
Took me like 6 hours to clean everthing, but what the hell, its was a Tropical rain-storm here in NJ, something you don't always see, had plenty of Coors and Vodka so made a day of it.
First time doing a complete service on a canister filter, there are some delicate parts in the pump part of the Pro3e, like the ceramic shaft for the impeller.
Used to cleaning AC110's.. Not looking forward to opening these filters anytime soon.
Took 1 photo and 1 quick video clip the next morning after the cleaning.
I think MR JAGGY likes it
video link
http://www.youtube.com/watch?v=MlmQ6Zh-d8M