Question about Magnesium, Calcium,Alk and water Changes

[Harville]

Hello Randy,

please bear with my ignorance.

I have been trying something new these few months and, so far, everything has improved greatly.

My new thing is using "reef crystals" (instead of I.O.) and I have went from changing five gallons of aquarium water a month ( 90 gal. tank ) to five gallons a week ( that's what I do now.)

I believe it has made a remarkable differance even though all water test kits have always indicated optimal water chemistry.

Also, I have been dosing ESV 2part Ca+Alk for the last two years or so. ( about 5ml of each twice a week ) Ca=stays between 390-430ppm Alk=2.6/8dkh according to Salifert.

But I have NEVER dosed or tested Mag. ( I know it is directly linked to Ca) A good friend of mine brought it to my attention ( he has an awesome sps only tank ) He tests for and doses Mag. on a regular basis. Whatever he does is definatley working for him, if you only saw his tank.

My question is this something I should work into my routine? I have always liked to keep things as simple as possible. Would the increased amount of water changes be sufficient to replenish Mag or will I be needing to buy another test kit soon?

Also what negitive effects would happen if I were to dose Mag? Would I have to increase the amount of Alk buffer?

I wouldn't start dosing this until I find out what level it was supposed to be at and got a quality test kit to help me monitor it.
But do you dose Mag. or do you think this is something I shouldn't worry about too much?

Thanks! Sorry this was so long!

[Randy Holmes-Farley]

My question is this something I should work into my routine? I have always liked to keep things as simple as possible. Would the increased amount of water changes be sufficient to replenish Mag or will I be needing to buy another test kit soon?


That depends on what the magnesium level in the salt mix is, how much is used by the tank, and how frequently and large you change water. I went for many years with only checking magnesium once in a few years. But in many aquaria it may be a necessary additive.

It also depends a lot on how you supplement calcium and alkalinity. If you use my DIY two part system, magnesium may (should) never get depleted. With B-ionic I am not so sure as I do not know exactly how much magnesium they add.

There are no negative effects of increasing magnesium to normal levels if it is low.

These articles may help:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php