HELP my calcium reactor keeps raising alk WAY To High

So my calcium reactor has been running for awhile now and everything was fine but now it is raising my KH to 11dkh + and not raising my calcium enough (without dosing something else it is only around 370-380 ) . What do I need to do to fix this problem ? I've shut off my cal reactor to get the KH back down to 8-9 but am afraid to turn it back on because last time I tried just shutting it off and turning it back on it spiked to KH again without raising the calcium .... Any advice would be GREATLY appreciated ..