Two part vs Limewater


New member
I'm in two minds over which setup would be best for my tank.

I'm currently planning on using dosing pumps, one for limewater and the other for the Mg.

I've read the articles and there are too many factors for me to compare.
Can I have a short and sweet comparison between the two part system and the limewater. Because I don't really see why you would use the two part except if dosing in different portions.

:D :D

rick s

Premium Member
This is just my opinion and I'm only replying to help you understand the differences.

If you have a low demand for calcium and alkalinity (not too many calcifying corals) then limewater will usually be the easiest, least expensive way to supply Cal and Alk. Many people add limewater to their top-off system. That is the easiest way to "dose" it. Limewater can only be mixed "so strong." You can only add as much as your tank evaporates each day.

As you add more and more calcifying corals, and they grow, the use of limewater alone may not keep up with the demand for Cal and Alk. You can then switch over to Randy's 2 part system, or continue to use limewater and start to dose Randy's 2 part system.

In a nutshell: Randy's 2 part system is much more potent (concentrated) than limewater. Therefore, you are not limited by your evaporation rate.

Many of us use limewater until it no longer keeps up. Then we look for other methods. By-the-way: Why are you setting up a dosing pump for Mg? Mg will not need to be added that often.


New member
Thanks rick that clears it up good and proper.

I'll just use the limewater until it's no longer sufficent.

A couple of reefers near me dose a fair bit of Mg to keep it up round 1350. Thought it would be better to trickle it in rather than dosing a heap each week.



New member
Just trying to find info on how much lime to add to the water. Read in the grandma article 3 teaspoons of lime and 45ml of vinegar per gallon.
Is this the saturated solution?
How do I work out how much calcium this will put into my system? and alkalinity changes? Thanks KP

Randy Holmes-Farley

Reef Chemist
Premium Member
Yes, that is about saturated. So is two teaspoons of lime and no vinegar. :)

2 teaspoons of lime per gallon of freshwater is about 80 ppm in calcium and 41 meq/L in alkalinity.

In what context do you need to know that?


New member
How is it that god made a supplement so perfect and in balance to califying corals available to reefkeepers. As it seems nothing in reef aquariums is without technicalities! :lol:

Thank God for lime :D (and its phosphate removal capabilities too)