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Here's a stand alone option:
http://www.bulkreefsupply.com/catalog/product/view/id/971/
http://www.bulkreefsupply.com/catalog/product/view/id/632/
PS I have the Air King BNIB if you're interested.
Two tsp. per gallon is the saturation point, after that you can add some vinegar. But, kalk by itself may not be enough to keep up with your demand. I would get your Ca and Alk up to where you want them, and start the kalk, and monitor the trend of use between WC's. You could start with 1 tsp...
Most, but not all of the Bristletooth Tangs would be a better choice for a tank of your size.
Here's an article:
http://www.reefkeeping.com/issues/2003-07/hcs3/index.php
Start with one tsp./gal., and watch the trend of your, Ca and Alk, if it isn't keeping up with your demand between WC's increase it. Also keep an eye on your pH.