auto top off and kalk

[spikehs]

I just bought some float switches off of http://www.floatswitches.net/ on ebay for my auto water top off. I plan on having the switch turn on when the water gets to low (duh!!) and have a back up one to switch it of when the water gets to high, just for added saftey. Anyways I have a big 40gal container that I want to have the kalk top off water in... do you think this would add the kalk to quicky? the switches are supposed to be accurate to withn 1/4 inch....

Thanks.