Why don't you start topping off with kalk using an
ATO. a reservoir is nice and cheap, you'd only have to mix it ever week or so depending on your set up. dont believe all that talk that kalk looses its potency over time; that happens only if the mixture is stirred and exposed to the air (after the initial mixing of course). check this article out, otherwise just do an experiment yourself. kalk would fix your alk struggles too.
http://www.reefkeeping.com/issues/2003-05/rhf/feature/index.php
Start making your own 2 part using dow flake and baking soda, its much, much, much cheaper. there are various ways to automate it. I'm looking into using auqualifters and precision valves on a digital timer. but rigging up a drip or using medical dosing pumps works well too i hear. those hobby dosing pumps are so costly, its really highway robbery.
if dowflake is not available in your part of the woods try from this place (20$ ish no shipping) or buckeye, theyve got the mag flake too. (which is used in conjunction with epson salts to maintain a balance of ions or some such)
http://www.tecprod2.com/files/display2.mv?specchem+IM50F
http://www.buckeyefieldsupply.com/showproducts.asp?Category=124&Sub=0
If you need to read up on how to mix your own 2 part read this good article, its what i follow. ive only used kent marine turbo calcium thus far but will buy dowflake once i run low. honestly even if i were to buy only the turbo calcium and baking soda its extremely cheaper than buying ready made 2 part. that stuff is highway robbery man! honestly to mix a gallon of each it probably costs like 2$ even when using turbo calcium. suffice it to say dowflake would be much cheaper.
http://reefkeeping.com/issues/2006-02/rhf/index.php
Also look into what kind of salt mix youre using, some have much more ca, alk and mag than others.
for reference on salt mixture comparisons check this thread on the RC
http://www.reefcentral.com/forums/sh...readid=1287118
I havn't read the whole thing *disclaimer* but I also started a thread here which evolved into some discussion about salt mixes here
http://www.manhattanreefs.com/forum/general-discussion/39671-where-do-you-buy-your-salt-locally.html