need help with h2o chemistry

[albie611]

two questions for those experts out there.
i noticed the frags in my frag system looked bad for the last 2 days and i ran a set of water test to check quality . this is what i found.

1: my frag tank has just had a sudden ph spike....it was 8.0-8.1 ....when tested this morning it was 8.6 with a alk reading of 8DKH and a calcium of 420ppm.
? how do i get it(PH) back to normal without doing anything drastic or affecting the alk and calcium.
if i added an airline to the tank would it help or make it worse?

2: my show tank(20 gal tall ), when tested today had readings of PH 8.1,alk 6DKH, and calcium 560.
now i know the alk is low and the calcium is way high so the question is how to get them back to the proper relationship again without affecting the PH, and doing anything drastic.
the only thing added to both tanks is kalk for top off and water changes every 4 weeks.

[sjames]

the pH spike is likely a testing error unless you started adding something beforehand, like lime water or a high pH alk booster like baked baking soda.

[Michael]

as for your 8.6 ph have alook at randys article it will help

http://www.reefkeeping.com/issues/2005-03/rhf/index.php

[bertoni]

For the 20 g system, dosing just baking soda for a while will add alkalinity without adding calcium. This calculator will help with a dose:

http://home.comcast.net/~jdieck1/chem_calc3.html