Where to find inexpensive dosing pumps

These are not pumps, but a cheap dosing solution I found. I'm considering them. The lack of sophistication is a little scary to me. I'm also not sure about having big gallon jugs sitting on top of my aquarium.

http://www.marinedepot.com/a_dp_kmad.asp

More information can be found here: http://www.kentmarine.com

Spectrapure sells an electronic pump sump switch that will add make up water to a sump tank etc as the level drops. You could add a 5 gal bucket of Kalk, add the pump and have it fill the sump as evaporation takes place.
Runs about 50$.
Gravity feed evaporation levelers also work well and have no moving parts, nothing to break and can have 1/4-1/2" out piping, nothing will clog.
Cheap, easy, relatively easy to set up to add X amount of Kalk or Ca per week.

If your tanks has 2 gallons of evaporation a week and needs 1 liter of kalk a week, well.....you can do the rest Evaporation rates are pretty stable generally. Sets up in the sump area above the water line, one end of a container is capped and the other is sitting at the water line. As the water line drops, air is allowed into the reservoir and the kalk/water is released until it's above the water line preventing more air from getting into the container/reservoir.
No narrow drip line to clog etc.

Easy to estimate what the Kalk needs are per week(or any other dosing you like), and evaporational losses.

Just add, refill weekly or whatever the routine is and that's it.

Often, simple is better.

Regards,
Tom Barr

Greg Hiller is selling a few over on reefs.org ... Greg is also a great source of frags...I think he still has a few pumps left

http://reefs.org/phpBB2/viewtopic.php?t=25013