Proper Alkalinity Level?

[zain]

What should the proper alkalinity level be? Please state the unit of measurement also - not just a number. Thank you for your help.

 

[geoj]

8-10 KH, GH, dH
2.857-3.571 meq/L
142.857-178.571 mg/L CaCO3

 

[ifirefight]

2.5-4.0 meq/l
7-11 dKh
120-200 ppm CaCO3

 

[zain]

Thank you so much! Have a great day.