You can subtract Ca from GH (normally Ca+Mg)...

Philippe


"Mark Trueman" wrote in message om...
| "Aqua" wrote in message ...
| Magnesium 3.8ppm (*LOW??*)
|
| How did you calculate this Mg Level?
|
| Its what's on the report from my water people. I dont think you can
| get test kits easily for Mg can you??