low alk (6dkh) and calcium 400ppm ???????
 

I'm cycling a tank, 20g, for 2 months now. I got matured live rock for another reefers tank and threw in a yellow tail damsel a month ago, hes doing good. Now I'm noticing a drop in alk. how can i get this back up, other than the obvious 10-20% water change. I think i herd somewhere that baking soda could raise alk? I am using tap water distilled for 24hrs (i know i should change, but all in good time). Anyone?

Here is a good recipe for calcium and alkalinity dosing:

http://reefkeeping.com/issues/2006-02/rhf/index.php

I have the same problem, so I'm along for the ride....

I punched in some stuff to the reef calculator site....I just always thought stuff was a balance, so I would mess everything up by adding things??

The correct balance of calcium is 400ppm when alk is at 6dKH.

Ahh, ok so what I was thinking was correct, that a balanced increase in both is what will correct the problem... up it to ~450 calcium and around 9 dkh....

That is about right. I personally only target about 430 for calcium and between 7 & 10 for dkh. (always nice to have it higher then NSW in case something happens)

Don't forget that unless magnesium id where it should be (above 1300 ppm) you won't get those numbers, as magnesium helps hold calcium in suspension.

For an explanation on how calcium, alkalinity, and magnesium interact with each other take a read through the link in my signature. I also suggest different products, and dosing methods.

Balanced Calcium and Alkalinity:

1.4 dKH to 350 ppm
2.1 dKH to 375 ppm
5.6 dKH to 400 ppm
9.1 dKH to 425 ppm
12.6 dKH to 450 ppm
16.1 dKH to 475 ppm

Personally, I aim for 9 dKH alkalinity and 420 ppm calcium. Generally, natural seawater contains 7 dKH alkalinity and 410 ppm calcium, so you can't go wrong imitating that either.

RGR, and I assume I have low Mg due to my salt mix......

What salt?

Instant Ocean, reported to be 1070 out of box......Mg tests are expensive so I've neglected to test this one thing...