Doeseing kalk

[bear27]

Ok heres my dilema

I have a 20 gallon tank,with a mixture of everything in it,sps,lps,softand clams

Know i had my perameters in check and was going to use the kalk to keep them level at 400ppm=ca and 9 dkh=alk but i found that i cant add enouf kalk before myph goes to high and my perameters are falling off right know there at 375ppm and 6 dkh

Im currently mixing 1 tbl spoon per 4 liters and its still falling off

Thats why I was hopeing the viniger would allow me to put more kalk in my tank unless you guys have a differnt solution