Carbonate lowering techniques?

[medic_eva]

So, if my test is correct, my carbonate hardness is 140. And, according to my kit, I am to contact my local authorities. So, is just a partial water change in order? The tank has been up for a week, had lotsa cured rock and sand go in it.

0 ammonia,
0 nitrites,
less then 5 nitrates...
And my pH, I have no idea what it is, the color the kit turns the water is PURPLE, and well, that's just not an option for chosing the color on the pack page. My guess is that it's either 8.3. or 8.5.
Calcium is around 440
Phosphate is 1

So what do I do about the carbonate? Is something else affecting it? In my books it only tells me about what to do if it's too low! grrrrr

Thanks!

Eva