Lawdawg wrote::welcome:
Well, the first questions usually asked are about the tank itself (setup) and your water parameters...that helps us to look for clues so if you could fill us it that'd be a help

Hi, thanks for the welcoming.
My tank info. 72 gal with plumbed 20 gal sump.I use a controller (rke v2) to keep temp @ a basepoint of 78.5F.Limewater is dosed through it as well 24/7 with the aid of a floatswitch and diaphram pump; no other chemical additives.Iuse seperate reactors for regular maintenece of rox carbon & gfo.
Parameters that I test for:
Ca.- 420ppm salifert
Mg.- 1500ppm salifert
Kh- 8.3-8.6 salifert
No3- 1ppm salifert (averaged,hard to tell but its between 0-2 per the higher range testing method
Refractometer calibrated with a commercial prepared indicator 35ppt before each use.
About the refractometer.I believe this might have been atleast part of the cause.I had no previous knowledge or experience with using one, and assumed it was accurate once calibrated.Over time I discovered it had drifted down to 1.020-1 or thereabouts.This is when I started to see what I think might be polypbailout but, Im not really sure if it is.Started around dec.2010/jan2011 it continues this progress to date.