The reason for that is because a kalk reactor holds a boat load of kalk! If you add straight kalkwasser to your system via a kalk reactor, it can and will raise your DKH, but that takes a substantial amount. If you use the top off method, you are only using 2 1/4 TSB per 5 gallons of water.... Essentially what I mean is Kalk reactor= tons of kalk where as ATO= very little kalk, diluted into FW.

When I first attempted to dose kalk I put WAYYYYYYYYYYYYYYYYYYYY too much. It shot my DKH to 14 or 15.... Tons of water changes later, I got it back to normal parameters, and did MY OWN research and found out I was putting in too much kalk powder into my ATO reservoir...

I have found it easy to dose with a ph monitor. I use ESV, which is not the best brand, but all I have to do is add the above amount and test the PH. If it's not 12, it's too old to use.