Levels fluctuating

[iceman86]

I checked the line and everything seems fine.
It can't also be salinity, I got an ATO that kicks in as soon as about a litres of water evaporates.

I wonder if one of my test kits have gone bad and it's giving me bad readings. Can it be caused by calcium or mag actually being too low? My alk kit is faily new and i compared the alk to my old kit and it's only .3dkh difference. The mag is a brand new kit but the calcium is needing replacement soon but still within expiry.