2 parts are MUCH easier to use but are also easy to develop an ionic imbalance and do nothing to stabilize pH. Kalk does not effect balance and if done correctly will not throw any params out of wack
dosing kalkwasser can be a pita if your not set up to do it but it is the most time tested method of meeting a tanks need for Ca while mantaining ALK and pH - it alone however will not meet the needs of a full blown SPS reef with large growing corals, that is why many high tech heavy people have gone to Ca reactors or Kalk stirrers and low tech people like myself use two part solutions and a kalk drip. now realize - i ran my 125 reef tank for over 10 years without any supliments of any kind but that is when i had mostly softies, shrooms and LPS's. i can't stress enough MOST TANKS DO NOT NEED any supliments at all, water changes are better, cheaper, and more effective. but if/when you start down the SPS road - suppliments do become neccessary.
for example, i do not dose anything in either of these 2 tanks of mine ever!:
so here are your options if your Ca and ALK are becoming high demand:
2 part - with your tank i estimate about 1/4 of a cup of liquid mix each per day (assuming your using a balanced solution like randy's 2 part) i add the buffer part at dusk and the Ca part at dawn. test weekly to see if that works, you may have to cut back or add more depending on your results. also before you do this you should have your params in order by doing a couple water changes and read randy holmes farley's many articles on the subject
kalkwasser - you need a mixing container. with your evap a 5 gallon bucket may work - i use a 35 gal plastic garbage can because my daily topoff is 2.5 gallons. the reason you need a seperate mixing container is that there will be a precipitate on the top and on the bottom and you want the clear liquid in the middle. i used a 5 gallon bucket for a while it had a hole with a valve 1" above the bottom so i could just open up the valve into a pitcher to fill my dripper. Now i have a pump in the resevoir with a hose leading to my dripper so all i have to do is hit a switch to fill my dripper - much more convient.
then using a dripper like this one
http://www.drsfostersmith.com/product/p ... 3677&rel=1
you drip ALL your top off water to the sump at night in the form of clear kalkwasser
my method is obviously not the easiest or only way to do any of this - but it works for me - look at my banner! there are many many ways to do the same thing, just keep in mind the simpler the better.
as far as feeding - i said that because so many people go to there LFS and buy frozen or liquid food suppliments and end up poluting their tanks. randomly adding anything to your tank is not a good practice, but LFS make their living selling people things they don't need. i do occationally target feed frozen mysis/cyclops/vitamin mix to my LPS just cause i like to watch them eat...
if you do target feed - do it first thing in the morning when the lights come on cause their feeding tenticles will be out already