Mikester
****UPDATED****
Mikester, your too right
I mix a super saturated kalk/lime, and drip right away. That means that I mix till my arm falls off, and then drip (1 drop per seond or so) and let about 1-2 gallons go into system over about 8 hours (after lights out to keep ph in check) try the vinegar method if ph swings too much. The stuff is super cloudy and hasnt settled into clear water. Most folks will let it settle out, the biggest diff is concentraion of calcium that makes it into your tank.
If you mix kalk with ro/di water then all the precipitate in the bottom of the bucket should contain minimal inpurities that would have been precipitated out with mix. City water may contain alot of impurities that mixing with kalk would help drag some of these out of the water and leave them in the bottom of the bucket, hence you shouldnt drip the stuff that settles out of water. They (they being most publications) reccommmend you drip the clear water (yes it contains the dissolved Ca. that you have mixed....)
If you drip the kalk water mix slowly you will affect the ph less than if you drip fast, or pour it staight into system. Pouring in large qty's of kalk too quickly then you can get a precipitate of magnesium, lowering those levels. If your mag is lower than what seawater contains, then your system has a hard time keeping a high level of calcium in solution (they work togther in harmony). But once we start trying to add more magnesium to make up for low mag, then it seems that we are knocking some other element out of whack. So if you cant test for it acurately, then its hard to add the correct amount to get it back into the correct range. I suggest administerring kalk slowly (ie. buy a 6 foot peice of flexible air tubing for an air pump, rubberband a rock to one end so it will sink into bucket, and then use a clamp to adjust the flow rate that drips into your sump, or tie a knot in the tubing and you can control flow by pulling knot tighter to slow flow, or looser to increase flow).. And I also suggest buying a mag test thats accurate (probobly pricey) before dumping mag into your system. Or start doing more water changes to help raise the level if you feel the mag levels have dropped.
Supersaturated (kalk that hasnt settled into clear water and powder on bottom, will give you a more concentrated calcium level that will be added to system, but must be dripped slower) kalk will help maintain levels and also seems to help maintain, and increase corralline algae populations.
BUT THE NUMBER ONE THING TO REMEMBER. Kalkwasser (lime water) is really only capable of maintaining calcium levels, rarely does it increase the levels in your system. If you have a low level of animals that use calcium in your system, then you may be able to raise the Ca. levels slowly with Kalk. If you maintain alot of LPS,SPS, Clams, then you will be able to maintain levels, but you may not be able to supply enough Kalkwasser to increase your calcium levels. And the reason is that you use water that your topping your system off with to make up your kalk solution. Most folks are replacing anything from a cup or two of top off water in those nano's, to 5 gallons + in those monster reef tanks. I run a 60 gallon with fuge and sump, the total possible volume of system is a guess at between 75 to 85 gallons(rock and coral and pumps and sand will displace water volume). I use about 1 gallon per day to top off my system to keep the salinity steady.
And at any given time I use kalk, lime, red-sea bio calcium powder, and kent two part buffer calcium additive. So if your Ca. levels are low, you need to pump the calcium level up with other additives before MAINTAINING it with kalk.
And if your worried about the white mud getting into your tank(dont pour it in your tank, but a little wont hurt anthing as long as its not settling in large clumps on your corals). The Neilsen reactor works by auto mixing a cylinder filled with water and kalk via a pump on a timer, and then slowly adds that to you system, and it has to dump some kalk power along the way as most have them set up on a drip, or top off switch that turns on the reactor empty spout (sorry for the vague terms) when top off needed, so there is not a realistic way to syncronize the mix pump, and the top-off pump to run on schedules that would keep the powder out of system.
I have super saturated for years, and no real problems I could ever link back to kalk. And I have even talked to Eric B about it, and he said that its OK!