Alkalinity & Magnesium dropping

[Clownfishy]

I have an issue where my aquarium is getting through more Alkalinity and Magnesium than I am Calcium. Therefore, is it possible or wise to dose just small amounts of Alkalinity rather than a two part? Since increasing my lighting period from 10 hours to 12 hours, I have noticed my Alkalinity and Magnesium dropping which I guess is expected as corals increase their growth due to the longer lighting. However, the calcium hardly drops. I slowly increase and decrease the lighting so there is not long periods of intense lighting.

Background Information
The aquarium is approx 190 litres and I change 10% of water weekly using Reef Crystals. I dose 2 litres of kalkwasser during the week and small amounts of Tropic Marin Bio Calcium http://charterhouse-aquatics.com/sh...ing/salt-water/tropic-marin-bio-magnesium-5kg. Could the problem be that there is an imbalance in this product?

I also, I seem to have to add quit a bit of Magnesium to maintain my levels. What would cause a high consumption of Magnesium over Calcium? I use Tropic Marin Bio Magnesium to maintain my levels http://charterhouse-aquatics.com/sh...ing/salt-water/tropic-marin-bio-magnesium-5kg

Water Parameters
Nitrate 5ppm
Phosphate 0ppm (I have a little bit of algae which I think it taking it up)
DKH 8.7
Calcium 460ppm
Magnesium 1310ppm
RedSea N0304-X 4ml daily
Bacteria dosing once a week

 

[Randy Holmes-Farley Verified Community Expert]

It is never the case that magnesium is being consumed and calcium is not.

The Tropic Marin Bio Magnesium and Biocalcium products are also adding alkalinity, despite the poor descriptions.

DO NOT try to dissolve the Tropic Marin BioMagnesium or Biocalcium in water (fresh or salt) before adding to the tank. It essentially makes them useless by precipitating calcium carbonate and/or magnesium carbonate/hydroxide. They must be added dry.

 

[Clownfishy]

It is never the case that magnesium is being consumed and calcium is not.

The Tropic Marin Bio Magnesium and Biocalcium products are also adding alkalinity, despite the poor descriptions.

DO NOT try to dissolve the Tropic Marin BioMagnesium or Biocalcium in water (fresh or salt) before adding to the tank. It essentially makes them useless by precipitating calcium carbonate and/or magnesium carbonate/hydroxide. They must be added dry.

Thanks for the info, I have been sprinkling them on top of the water and it certainly raises my Magnesium but I seem to maintain Calcium but Magnesium and Alkalinity seems to drop quicker. Can I just use the baking soda recipe you provide to maintain just the alkalinity or would i start to run into imbalance issues?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the info, I have been sprinkling them on top of the water and it certainly raises my Magnesium but I seem to maintain Calcium but Magnesium and Alkalinity seems to drop quicker. Can I just use the baking soda recipe you provide to maintain just the alkalinity or would i start to run into imbalance issues?

Magnesium never drops more than about 1-2 ppm per day. Anything substantially more is testing error, and magnesium testing error is super common. People seem to especially have issues with the Red Sea kit.

How much are you adding?

The whole world of newer reefers says their alk is dropping and not their calcium, when in reality both are usually dropping in the expected ratio and they just do not see the calcium drop because it is often below the sensitivity level of the kit.

If you are seeing a 0.3 dKH per day drop in alkalinity, the expected calcium decline is only about 2 ppm, and the magnesium drop is well below 1 ppm. Neither the calcium nor magnesium drop will be detected by kit for a long time of experiencing this drop.

 

[Clownfishy]

Thanks, I have some new test kits so I will try them tomorrow as it sounds like I may have a testing issue. Will report back, many thanks

 

[Randy Holmes-Farley Verified Community Expert]

OK, let us know what you find.

 

[Clownfishy]

Tested with a new test kit today and it read the same. Will continually add a level spoon of Bio Magnesium each day which is well within the maximum until I get to about 1400. Will keep an eye on the alkalinity levels. Below are the last 3 weeks reading of Alk, Calcium and Magnesium.

9.1 455 1300
8.7 460 1320
8.9 455 1320

 

[Randy Holmes-Farley Verified Community Expert]

Just be careful that alk doesn't rise too much since that magnesium additive is boosting alk too.

 

[Clownfishy]

Just be careful that alk doesn't rise too much since that magnesium additive is boosting alk too.

Thanks I didn't realize that. Will test Alk before adding any more.