I just went through the same thing with my Red Sea Test Kit. My readings were 380 and I was increasing my dosing. In the end I was well over 500 and my kit still read 380. I stopped dosing and it took over 2 weeks for the level to drop to 400. New Red Sea Test kit compares to my Salifert one now. Mine was not in the recall range as well.

I would suspect the Red Sea kit if my other kits readings where different but they where exactly the same.

Tested again after my water swap with all 3 kits, all read 500.

Also checked the expire date on all the kits as well, not even close to the date of expire.

Will do another water swap tomorrow night.

What salt brand are you using?

I am setting up a new system using IO and have high readings.

From my understanding, high levels of calcium do not cause adverse effects on anything except on inverts. Corals can only absorb so much. With a high alkalinity, it can be a problem - but if your alkalinity is fine, I don't think there is much to worry about, except for calcification doing damage to pumps and equipment.

If you do a dramatic decline in calcium, you would also see a decline in alk.

http://reefkeeping.com/issues/2006-06/rhf/index.php

You are much more educated on the subject than I am. However; the article above might help your mind ease regarding the increase.

Using Reef Crystals as always :biggrin: