Geothermal blue green slime

oldfart

Good Morning ,

I work for a heating and Ac jobber in central Pennsylvania . We do quite a bit of geothermal water to water systems =( low temp , 90 to 120 degrees . ) In the past two months we have found three different systems that have the blue green slime that I have read about in previous threads .  The common link between all of these systems are radiant NB pex tubing . One system has methanol freeze protection , installed by another contractor , the other two have none .They all have  brass manifolds . limited copper and brass . One system was severe enough we lost water flow thru the manifolds . These systems are all well water , closed loop on the source side . Yesterday we found a closed loop system on the source side with methanol that has the blue green slime, but with a slight hint of reddish brown specks . These four homes are probably 20 miles apart . The funny thing is is that we have not seen this in a high temp system ( boilers ) .Previous posts have suggested iron bacteria turned blue . They also have suggested well drillers bringing contamination from well to well .  We have been installing these systems in this same manner for the previous 10-12 years without ever seeing this and now we have been slammed with four systems in two months .



Any help ?

icesailor

Slimey Anti-Freeze:

First of all, are they really using Methanol as a fluid conductor in these Geothermal systems? That's a no-no as is using Ethylene Glycol.

Scrape some of the blue scuzz and put it in straight white vinegar  Let it sit overnight. If it is gone, it is calcium carbonate or some other form of hardness precipitating out of the well water. Have the water tested for what's in it and especially hardness.

If the PH of the well water is historically dropping since the well went in, and the screen is set in limestone, the carbon dioxide, licked up in the limestone can be coming out and the calcium carbonate is dissolving in the water as a form of hardness. It sticks to heated or dissimilar surfaces.

Get the water checked.

Methanol doesn't belong in a potable water system.

oldfart

slime update

These are closed loop , heating only pressurized , radiant, non- barrier pex tubing systems . The source side(wells) are also closed loop systems . We did not introduce the methanol . We inherited the systems . There is no fresh water being used in these systems .