Auto Top off with Kalk Reactor

I have been having trouble with my kalk system on my 20g.  Mostly the powerheads don't last because they get so encrusted with Calcium Carbonate.  I have been thinking of a way to make the kalk system work without having Kalk push through a powerhead. 

Here is what I have come up with:  Have a reservoir to hold the RO/fresh water, build an auto top off similar to jfinch's design that will pump water into the bottom of a reactor/kalk reservoir.  this pumping of the water into the reactor will serve as the only mixing agent.  The reactor will simply overflow into the sump/'fuge. 

I know that everyone has suggested that you only use the clear effluent from a kalk reactor, but isn't the biproduct almost entirely Calcium Carbonate?  Isn't that what our sand is made of?  If I put this contraption in the refugium where there is sand already won't it just put a small layer on top of the already dissolving sand?  The top off points would have to be really close together so that not too much kalk would get added at one time and cause large pH swings.

What do you think?  Let me have it, I have thick skin.

Thanks,

Fax

If it doesn't throw your pH too high it'll be just fine (this goes for any/all methods of adding lime).  I doubt you'll be adding a saturated solution doing it as you suggest, but that may not matter anyway.

How much does your top off system pump out at one time?

My auto top off or my kalk reactor?  My auto top off is RO/DI water and it will add until the upper float switch in my sump is lifted.  My kalk reactor uses a peristaltic pump from www.reefdosingpumps.com and maxes out at 300 ml/hr (almost 2 gallons per day) and will drop down to 1 ml/hr.  I am currently trying to make up all my evaporated water with my kalk reactor and it's adding 125 ml/hr (0.8 gallon/day).

With a relatively fresh charge the pH in my current reactor is only about 10 or so.

Yeah, that is a very weak solution.  pH isn't the best way to measure the strength of kalkwasser.  A saturated solution will have a pH of 12.4, but even a very under saturated solution will have a pH above 10-11.