that is really strange. my 180 varies very little from day to day. i'm not a chemist but your readings seem unreasonable to me. could it be your test procedure or kits? i use the salifert tests and usually my varience is < .4 dKH, 0.0 pH and 20ppm CA between tests and i don't usually do them even weekly. i do all my testing at exactly the same time of night.
this is the best link that i've seen describing CA/alk relationship:
http://www.advancedaquarist.com/issu.../chemistry.htm
if you are sure your tests are good, i would suggest you do the following:
1) do a series of large water changes to get your system back in balance. 30-40% 2 or 3 times.
2) do all of your tests at the same time.
3) use only kalkwasser, c-balance, bionic or a calc reactor to get you where you need to be.
4) don't add too much at a time.
5) make sure you are at full strength 35 ppt saltwater.
i'm trying to get my ca up as well. added a calc reactor a few weeks ago and am still dosing bionic and kalkwasser. my pH is always 8.4, ca is at 340 (going up 20 ppm/week) and alk is at 6.4 dKH.
good luck!
bill
