1200ppm Mg with Salifert test

[Karen00]

Hello fellow saltines,

This is my first time doing a magnesium test. I bought the Salifert test kit. There are no coral in the tank yet and I don't do any dosing. There are a couple fish and at some point I want to keep softies. The test gave me 1200 ppm. Should I raise this with dosing if I want to keep softies? My Google searches gave me 1250-1350ppm for mag for softies. The tank is only a few months old but CA has been pretty steady at 440ppm and Alk at 214ppm.

 

[JGT]

That seems rather low with no corals in the tank. Even with corals MG depletion is slow. I would run another test. Make sure you stop adding drops as soon as you see color change from purple to blue or gray.

 

[Karen00]

That seems rather low with no corals in the tank. Even with corals MG depletion is slow. I would run another test. Make sure you stop adding drops as soon as you see color change from purple to blue or gray.

Thanks for this. I too thought it was low. I've been meaning to look at my bag of salt to see what it "should" be. Have you used Salifert? Maybe I'm doing/reading the test wrong although I read the instructions thoroughly and watched a YT vid. When I draw out the mg-3 solution to 1ml I get an air gap of about .2ml leaving .8ml of solution (supposedly this is normal?). When I added the drops to change the color (for me it turns blue) the plunger is at .2ml then there is an air gap and then about .02ml of solution. If I'm understanding the instructions correctly then I read the level at the plunger. If I read at the level of the remaining solution then it's more like 1475ppm.

I guess my questions are:
- Am I reading the results correctly (at the plunger)?
- Is .2ml of an air gap correct when drawing out the mg-3 solution?

I will definitely redo the test.

 

[JGT]

Yes, you read what’s left at the bottom of the plunger. The air gap is normal. This accounts for the liquid that goes into the tip of the plunger so it offsets. Again make sure the bottom of the plunger goes to 1 ml when you draw it out.

 

[redfishbluefish]

Yes, your syringe reading appears correct.

My questions are:

1. What salt are you using?
2. At what salinity?
3. And what are you using to measure salinity?

 

[Saltyreef]

I always test 2-3 times if i didnt get what i expected.

Read the salifert syringe @ the black plunger line. I always draw a full syringe and squirt it back into the bottle slowly then draw another full syringe and purge the air out while pushing the plunger to the 1ml mark.

Ive had airgaps before sucking the solution up too fast.

 

[Karen00]

Yes, your syringe reading appears correct.

My questions are:

1. What salt are you using?
2. At what salinity?
3. And what are you using to measure salinity?

Thanks for your reply...
1. Fluval Sea Pro salt. I was given this bag for free (new/unopened) so I didn't want to waste it. Since opening it I have had a lot of clumping from humidity in the air. I haven't purchased an air tight container yet. The salt used to mix clean but since it started clumping I have noticed a lot of particles at the bottom of my mixing bucket. Could this be precipitate that's affecting the mg?
2. 1.026sg
3. A digital salinity meter for saltwater but I confirmed the reading with my LFS.

 

[Karen00]

I always test 2-3 times if i didnt get what i expected.

Read the salifert syringe @ the black plunger line. I always draw a full syringe and squirt it back into the bottle slowly then draw another full syringe and purge the air out while pushing the plunger to the 1ml mark.

Ive had airgaps before sucking the solution up too fast.

Thanks for this. I will definitely try it again. I thought I was drawing it up slowly but it still could've been too fast. Ironically when I remove the tip it draws up with almost no air gap however I used the tip to do the test.

Come to think of it I removed the tip to do the drops of the mg-3 solution. Does this make a difference? Should I leave the tip on? This might be my "ah-ha" moment.

 

[Saltyreef]

Thanks for this. I will definitely try it again. I thought I was drawing it up slowly but it still could've been too fast. Ironically when I remove the tip it draws up with almost no air gap however I used the tip to do the test.

Come to think of it I removed the tip to do the drops of the mg-3 solution. Does this make a difference? Should I leave the tip on? This might be my "ah-ha" moment.

Pink tip stays on

 

[Karen00]

Pink tip stays on

That is probably why I got those results. I will retest and post here.

 

[redfishbluefish]

I also just looked up Fluval salt and had to calculate magnesium at 1.026 salinity, and it came to 1287 - 1338.


EDIT TO ADD

Just found a reference of Fluval salt at 1.026 (HERE) and these are the published values.

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Ca (ppm)................... Alk (dkh)....................Mg (ppm)

Fluval Sea

490

8.6

1425

 

[Karen00]

I also just looked up Fluval salt and had to calculate magnesium at 1.026 salinity, and it came to 1287 - 1338.


EDIT TO ADD

Just found a reference of Fluval salt at 1.026 (HERE) and these are the published values.

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Ca (ppm)................... Alk (dkh)....................Mg (ppm)

Fluval Sea

490

8.6

1425

Thank you! After seeing this I'm quite certain I messed up the test. I'm sure it's because I took the tip off the syringe when adding the mg-3 solution and I should have left it on. Doh (sound of Homer Simpson ringing in my head). Haha. I'm going to retest and repost my results.

 

[redfishbluefish]

My "Doh" list is endless.

 

[Karen00]

So I did the test again with the tip on the syringe and it's a bit better at 1260ppm. I think I'm getting too much of an air bubble. I'm going to try again in the morning. I'm also going to test the water in my mixing bucket. I'm contemplating buying the Hanna Checker for this one. I feel like the mad scientist with all of my powders and liquids and syringes when I do this test. I have flashbacks to high school chemistry class (I won't say whether they're good or bad).

@redfishbluefish My list of doh's is near endless at this point. Haha.

 

[Billdogg]

All the advice you've gotten so far is spot on. The only thing I would add is that of all the test kits, the Mg is the most finicky. Do it exactly as it says. I use the stopwatch on my phone to time the swirling. Also, try doing the test 2 or three times in a row and average the results. That will minimize any user error in the testing process.

 

[Karen00]

All the advice you've gotten so far is spot on. The only thing I would add is that of all the test kits, the Mg is the most finicky. Do it exactly as it says. I use the stopwatch on my phone to time the swirling. Also, try doing the test 2 or three times in a row and average the results. That will minimize any user error in the testing process.

Thank you for this! Finicky is an understatement for this test. Haha. I'm going to try again today on my tank as well as my freshly mixed salt. Being new to the hobby it's a bit distressing when tests return results quite different than what you expect, especially when, in my case, it's a fish only tank at the moment. Aargh!