9 years ago, we had our 2.5 ton system replaced with a 3.5. Now, we have visible mold on the vents. Yesterday, we were told that our duct work was sized for a 2 ton, and that was the root cause. Their suggestion was a full duct redesign and replacement and HEPA filter with RGF/REME system. The price tag was staggering. This is a average middle class ranch home in central florida built in the 70's, and we plan on being out of it in 5 years anyway, so no way am I doing massive renovations. Reading here, I already see that the RGF/Reme/Hepa thing is likely just expensive hyped crap. And general research says taking care of my humidity problem, which means taking care of my airflow problem, will cause the mold to die off on it's own. So here is my big question... since the bottom line is I have too little airflow in and out of the air handler, wouldn't adding a few appropriately sized vents and returns fix that problem? I realize it will not be balanced, and it will not make my warmer rooms cooler or my cooler rooms more comfy...all things the proposed complete redesign would do... but I also don't think it will cost me 15k either. Simply looking for the most realistic answer here... would like the mold to be gone, and my system to run efficiently, which will hopefully lower my electic bill; beyond that, I am not looking for massive redesign, perfection, rocket science or magic. Thanx for any input.