Mg Keeps dropping, why?

Tmcgoo13 · May 22, 2018

Today woke up to cloudy water in my Peninsula 650. Tank is about 4 months old. I’m guessing that is a bacteria bloom.

The main problem I keep having is Magnesium keeps dropping. I’m using Red Sea Coral Pro salt, and Reef Foundation A, B, C

MG had dropped all the way to 1200 before I started raising it slowly. I had it at 1360 two days ago and now its at 1280.

Mg 1280
DKH 8.4
Ca 365 (this keeps going down as well)
Nitrate 0
Phosphate 0.04
Salinity 1.024
Ammonia 0

Any ideas what would consume the MG and Ca, hardly any coral in the tank.

Randy Holmes-Farley · May 22, 2018

There is zero possibility the magnesium dropped 160 ppm in 2 days. That is testing error.

Consumption is in about the ratio of 2.8 dKH of alk, 18-20 ppm of calcium, and 0-2 ppm of magnesium.

Tmcgoo13 · May 22, 2018

Randy Holmes-Farley said:
There is zero possibility the magnesium dropped 160 ppm in 2 days. That is testing error.

Consumption is in about the ratio of 2.8 dKH of alk, 18-20 ppm of calcium, and 0-2 ppm of magnesium.

I know doesn’t make sense, tested with Red Sea and Salifert, got same result within 10

Randy Holmes-Farley · May 22, 2018

There’s still no chance. Might be right now and wrong before, but there’s no mechanism for magnesium to drop like that. [emoji3]

Scorpius · May 22, 2018

I use Salifert Magnesium test kit and I usually get 30-50 ppm variance from test to test. Best practice is to test three times and average them out. Remember these are hobby grade test kits with hobby grade results.

Tmcgoo13 · May 24, 2018

Randy Holmes-Farley said:
There’s still no chance. Might be right now and wrong before, but there’s no mechanism for magnesium to drop like that. [emoji3]

Randy, so its clearly low, regardless of how fast it drops. I measure 1260 and need to raise it. What’s the amount of change that is acceptable in a day? I have Red Sea Reef Foundation C (MG). Your calculator doesn’t show that, so I’ve seen as high as 100ppm per day. But Red Sea shows 10ppm per day.

Scorpius · May 24, 2018

I do 50ppm a day without any issues. YMMV.

Randy Holmes-Farley · May 24, 2018

Tmcgoo13 said:
Randy, so its clearly low, regardless of how fast it drops. I measure 1260 and need to raise it. What’s the amount of change that is acceptable in a day? I have Red Sea Reef Foundation C (MG). Your calculator doesn’t show that, so I’ve seen as high as 100ppm per day. But Red Sea shows 10ppm per day.

How high do you want it?

IMO, the magnesium change is not so much the concern as impurities that may come with it. There’s no fixed amount, but slower is better. 25 ppm in a day is usually fine.

Tmcgoo13 · May 24, 2018

Randy Holmes-Farley said:
How high do you want it?

IMO, the magnesium change is not so much the concern as impurities that may come with it. There’s no fixed amount, but slower is better. 25 ppm in a day is usually fine.

Trying to get to ~1350. I’m using Red Sea, I saw another post of yours about the impurities comment. Would you consider Red Sea a high grade (ie low impurities) option?

Randy Holmes-Farley · May 25, 2018

Tmcgoo13 said:
Trying to get to ~1350. I’m using Red Sea, I saw another post of yours about the impurities comment. Would you consider Red Sea a high grade (ie low impurities) option?

Probably, but I don't really know. The value you are at currently is perfectly fine, and so is raising it. Consequently, there's no rush and I'd spread the boost out over a few days.