High Alkalinity and Magnesium Consumption

[Clownfishy]

Question 1 - Magnesium
Several weeks ago, I noticed my magnesium levels dropping and I am now supplementing Magnesium at a rate of 2ml of Aquaforest Magnesium daily to a 75 litre (20 US gallon) nano reef. My understanding is that high coralline algae growth can be the cause of this? If so, why is it only Magnesium it consumes as I have not seen any drop in Calcium?
Since dosing Magnesium at this level, my red Montipora has really coloured up and I had noticed it looking a drab colour previous to this.

Question 2 - Alkalinity
A couple of weeks ago, I added 10lbs of Natures Ocean Samoa Pink live sand to the same nano reef which had previously been bare bottom. I understand that it is expected for Alkalinity consumption to increase after adding sand but any ideas how long I should expect this process to take as I am now dosing approximately 16ml of Alkalinity for every 7ml of Calcium!!! By the way, all the corals look great so this level of dosing has not "yet" caused any issues.

 

[blaxsun]

Assuming something's not off with your testing kit(s), coralline growth can especially suck magnesium (for that size of tank, it still seems high, though).

 

[Clownfishy]

Changed to a new Magnesium test kit and it is still reading the same. I have just tested my Calcium and I now see that dropping as well. Hard to say if it was the sand or whatever the cause of the Magnesium uptake, or a combination of both but has dropped from 460 to 430. Therefore, I have now increased my two part to dose 16ml Alkalinity and 8ml Calcium and 8ml Aquaforest Minerals. Still dosing an additional 2ml of Magnesium a day so will keep it like this and see how we go. I am now hoping either my Calcium dosing will need to increase to the Alkalinity dosing levels or my Alkalinity dosing will need to drop to my Calcium levels.

I did not expect it to drift this far apart for so long!

 

[gbroadbridge]

Changed to a new Magnesium test kit and it is still reading the same. I have just tested my Calcium and I now see that dropping as well. Hard to say if it was the sand or whatever the cause of the Magnesium uptake, or a combination of both but has dropped from 460 to 430. Therefore, I have now increased my two part to dose 16ml Alkalinity and 8ml Calcium and 8ml Aquaforest Minerals. Still dosing an additional 2ml of Magnesium a day so will keep it like this and see how we go. I am now hoping either my Calcium dosing will need to increase to the Alkalinity dosing levels or my Alkalinity dosing will need to drop to my Calcium levels.

I did not expect it to drift this far apart for so long!

Exactly which Aquaforest products are you using?

I use Aquaforest in my main tank, but there are a number of products you could be using.

 

[Clownfishy]

Aquaforest Mineral salt as my 3 part (with the addition of their Magnesium). I also use their Components Strong in Calcium Chloride and Soda Ash (Randys DIY formula). When my Magnesium started to drop, I made up some Magnesium from their Magnesium product and that is what I am dosing in addition to try and bring my Magnesium levels back to 1350.

 

[gbroadbridge]

Aquaforest Mineral salt as my 3 part (with the addition of their Magnesium). I also use their Components Strong in Calcium Chloride and Soda Ash (Randys DIY formula). When my Magnesium started to drop, I made up some Magnesium from their Magnesium product and that is what I am dosing in addition to try and bring my Magnesium levels back to 1350.

The reason I asked, is because if you are mixing Mag per their instructions (10g/1000ml water) a 2ml dose in a 75l tank will not make a measurable difference.

If you're seeing a difference it must be a test error.

 

[Randy Holmes-Farley]

Magnesium consumption is never more than about 1/10th of the calcium consumption, even for coralline.

 

[gbroadbridge]

Aquaforest Mineral salt as my 3 part (with the addition of their Magnesium). I also use their Components Strong in Calcium Chloride and Soda Ash (Randys DIY formula). When my Magnesium started to drop, I made up some Magnesium from their Magnesium product and that is what I am dosing in addition to try and bring my Magnesium levels back to 1350.

If you're using the Aquaforest basic elements as designed (which is a modified Balling method), you should be dosing all three parts *equally*. This will maintain the tank water balance.

This is especially important if you are adding the Components Strong Trace elements mix to the three dosing solutions.

If you need to make one off adjustments to correct a deficiency, use the reef dosing calculator below and select the Aquaforest element needed, mix the appropriate amount with some RODI water and slowly add to a high water flow area.

To bring Mag up from 1250ppm to 1300ppm in a 75 litre tank requires the addition of 32g of Aguaforest Magnesium over a couple of days.

Reef Chemistry Calculator

 

[Clownfishy]

Many thanks for the responses. As my Calcium is now decreasing, I am bringing my Calcium and Mineral salt dosing inline with the Alkalinity dosing. @gbroadbridge , you are right, I should have kept all the dosing inline all along. I only increased the Alkalinity initially as it began dropping so quickly and I did not see the same drop in Calcium so that was a mistake on my part, especially as I am addin Aquaforest Components Strong.