For years I struggled with hard water residue from ballasting my gliders. Calcium / lime spots under the wings and tail dump valve leaks were very annoying. Suggestions to remove the spots under the wings and along the rudder went from fine grit sandpaper to CLR or Lime Away. Both methods work, but take some elbow grease. CLR in the tail ballast tank once or twice a year took care of my Discus 2b tail tank valve leaks quite nicely.
However, some years ago I went one step farther and decided to treat the water before I loaded up my glider. I stopped by Walmart and bought an RV water filter ( https://www.walmart.com/ip/Camco-40043-Tastepure-RV-Marine-Blue-Inline-Water-Filter-with-Flexible-Hose-Protector/249436248 ). This is a common item wherever RV supplies are sold. Use this inline when filling ballast tanks. Flying my ASH 31 at desert or mountain soaring sites for the past 5 seasons I've never had to remove hard water spots from under my wings.
Give it a try. it's cheap and easy.
Craig

On Friday, October 29, 2021 at 2:34:32 PM UTC-7, Craig Reinholt wrote:
> For years I struggled with hard water residue from ballasting my gliders. Calcium / lime spots under the wings and tail dump valve leaks were very annoying. Suggestions to remove the spots under the wings and along the rudder went from fine grit sandpaper to CLR or Lime Away. Both methods work, but take some elbow grease. CLR in the tail ballast tank once or twice a year took care of my Discus 2b tail tank valve leaks quite nicely.
> However, some years ago I went one step farther and decided to treat the water before I loaded up my glider. I stopped by Walmart and bought an RV water filter ( https://www.walmart.com/ip/Camco-40043-Tastepure-RV-Marine-Blue-Inline-Water-Filter-with-Flexible-Hose-Protector/249436248 ). This is a common item wherever RV supplies are sold. Use this inline when filling ballast tanks. Flying my ASH 31 at desert or mountain soaring sites for the past 5 seasons I've never had to remove hard water spots from under my wings.
> Give it a try. it's cheap and easy.
> Craig

Try using a ceramic protective coating. I did that and have no deposits on my wings. I have previously described how to apply this coating.

Tom

On Friday, October 29, 2021 at 4:29:46 PM UTC-7, 2G wrote:
> On Friday, October 29, 2021 at 2:34:32 PM UTC-7, Craig Reinholt wrote:
> > For years I struggled with hard water residue from ballasting my gliders. Calcium / lime spots under the wings and tail dump valve leaks were very annoying. Suggestions to remove the spots under the wings and along the rudder went from fine grit sandpaper to CLR or Lime Away. Both methods work, but take some elbow grease. CLR in the tail ballast tank once or twice a year took care of my Discus 2b tail tank valve leaks quite nicely.
> > However, some years ago I went one step farther and decided to treat the water before I loaded up my glider. I stopped by Walmart and bought an RV water filter ( https://www.walmart.com/ip/Camco-40043-Tastepure-RV-Marine-Blue-Inline-Water-Filter-with-Flexible-Hose-Protector/249436248 ). This is a common item wherever RV supplies are sold. Use this inline when filling ballast tanks. Flying my ASH 31 at desert or mountain soaring sites for the past 5 seasons I've never had to remove hard water spots from under my wings.
> > Give it a try. it's cheap and easy.
> > Craig

That's interesting because my understanding was that filters can't remove calcium from water. The advertisement for the filter you link has a long list of stuff it does but removing calcium isn't on their list. It is described as a KDF plus activated carbon filter. I just did some googling confirming that medium does not pull calcium from the water. So how can it be preventing the hard water buildup on your wing? Perhaps there's something more to making a hard water deposit than just calcium and that something more is being removed? Is there a chemist in the house?