My system has been running real solid for about 2-3 weeks now but I seem to be losing about a 1/4cm of water level in my t-line approximately every 3 days. My tubing is Masterkleer 7/16" diameter and I probably have about 14' of it total in my loop. What kind of permeability does this tubing have? Is this a normal amount of loss for a completely sealed system or should I look into the possibly of a micro leak somewhere? Thanks for your input.