KH 170, Ca 260, Can't get it up.

[Ruth]

You should reveiw Bev's chemistry links that are a sticky in this forum to fully get the whole picture. I like to try to keep my levels at close to NSW (Natural Sea Water) so here is what I try to shoot for - a little more or less is not that big of a deal:
Alk - 2.9 meg/L or KH of 8 dKH
Calcium - 400 - 425 ppm
Magnesium - 1300-1500ppm

I have always used Salifert test kits to test the majority of my levels in my aquariums. They are easy to use and from what I have read fairly accurate. The only one that I am convinced is not very accurate is the Phosphate test kit.

As with everything in this hobby good things happen slowly and bad things happen quickly.

If I was you I would be tempted to either take a sample of your water into a LFS to have it tested or to a friend that has all 3 of the above test kits to double check for accuracy. See where you are at with all 3 and then go from there - slowly adjusting, testing and re-testing. Over the course of a week or two you should be able to adjust.

I can't remember what size of a system you are running but if it is not that big the easiest thing to do may be to just do a few large (50%) water changes.
HTH