Magnesium at 1500ppm

[Ralistin]

Randy, I have never dosed any type of magnesium suppliment ever in my tank. The only exception to this was a 1 1/4 cup dose of part three of your recipe about 8 days ago. Before this dose I had a Magnesium reading of 1350ppm. Now it is at 1500ppm and I am ready for a second dose. I don't understand how my magnesium remains so high. All that I add to my tank is food and ro/di water. The last water change was in late November when I moved my tank.

1) Why does my magnesium remain so high?

2) Should I not dose part three since I currently get a reading of 1500ppm.

3) If I don't dose part three, how long before it becomes important to do a water change to reduce the elevated chloride levels?

 

[Randy Holmes-Farley]

The kit may not be accurate, but I wouldn't add any magnesium if the level is above 1350 ppm.

Have you tried measuring magnesium in your salt mix? Some, like Oceanic, have excessive magnesium.

How much did you add, and was it to the 75 gallon tank you mention in your sig? This calculator shows how much the magnesium should have risen:

Reef Chemicals Calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

 

[Ralistin]

The test kit is Salifert. I bought it last month. It could be a bad kit but I have no way of knowing that right now.

I have not mixed my own salt water in months. When I moved my tank in November I did add 24 gallons of salt water from a LFS that says it came from the ocean. Other then that I only add ro/di water for makeup.

I do plan to do a large water change tomorrow.

I just don't understand how the magnesium levels have not dropped at all over the course of the last month since I started to test for it.

 

[Ralistin]

Yes, 75 gallon described in my signature.

 

[Randy Holmes-Farley]

Magneisum is not rapidly depleted, so it would not surprise me that if the water had excessive magnesium in it initially, that it still would. They may be using Oceanic salt, or something they modified, despiite the claim.

Assuming that you made my recipe according to the directions, and added 1.25 cups of the liquid, that would boost magnesium by about 50 ppm.

 

[reverendmaynard]

Re: Magnesium at 1500ppm

<a href=showthread.php?s=&postid=6718269#post6718269 target=_blank>Originally posted</a> by Ralistin
The only exception to this was a 1 1/4 cup dose of part three of your recipe about 8 days ago. Before this dose I had a Magnesium reading of 1350ppm. Now it is at 1500ppm and I am ready for a second dose.

You've used a gallon each of recipe 1 in a 75g tank in 8 days? Must be wall to wall sps in there.:eek2: :eek1: :rollface:

 

[Ralistin]

Yeah, in 8 days is about right. My calcium will drop quickly in a day if I add nothing.

 

[Ralistin]

I do mainly have SPS corals but certainly not wall to wall or even close.

 

[Ralistin]

Randy, I will do a water change with Instant Ocean and see how that works out for me. I figure about 30% will be my target.

 

[Randy Holmes-Farley]

OK, sounds good.

Good luck.

 

[Ralistin]

Hi Randy. I did a 35% water change today and tested my params about an hour later. I am still confused as to why magnesium is so high. I did the water change all at once too. I removed 28 gallons and then added 28 new gallons of water.

Magnesium = 1500ppm
Calcium = 500ppm
Alk = 9.2 DKH

I did not test Magnesium beforehand but calcium was at about 580ppm and Alk was 7.4DKH

Any ideas why this might still be so high?

Thanks!

 

[Ralistin]

I should have tested the new water but I didn't unfortunately.

 

[Randy Holmes-Farley]

Yes, I'd check the water next time. It may be high in magnesium, and maybe calcium. It may also not be NSW.