Jump to content
Pod Your Reef

To dose or not to dose Mg ?


FishFrog

Recommended Posts

After a round of tests this morning, we found out that our Magnesium is really low - at 900ppm.

All of the other results were relatively normal. Ca is at around 400.

 

We do weekly 10% water changes with Reef Crystals salt. The tank mainly has LPS coral.

 

I thought that weekly water changes with a good salt mixture would mean you don't need to dose Mg? We only recently started dosing Calcium, after that was low too. I reckon it is because we have so much coralline - it literally grows like crazy.

 

From what I have read here: http://www.advancedaquarist.com/2003/10/chemistry this could also be responsible for depleting the Magnesium levels.

I am also reading that dosing Mg can take a long time to get it back up to decent levels.

 

Should we do extra water changes or just start dosing? Or a combination of both?

 

Does anyone have any successful experiences to lead us in the right direction?

 

Thanks in advance!

 

 

Edit: all the measurements

Tank:

pH 7,7

Alk 9 - 10

Ca 425

Mg 1060

Sg 1.022

 

WC water:

pH 8

Alk 7 - 8

Ca 400

Mg 1125

Sg 1.022

Link to comment

What's your alk? If it's normal and ca is 400 your mg isn't 900. RC is high in all three and mg isn't depleted much.

Thanks for the reply! Our alk is at 9 right now. Does it make a difference that we are dosing Calcium?

Link to comment
Thanks for the reply! Our alk is at 9 right now. Does it make a difference that we are dosing Calcium?

 

No not really, it would probably just precipitate out with mg at 900.

Link to comment

No not really, it would probably just precipitate out with mg at 900.

Okay. Well we're testing again, if it stays the same I'll take a sample to the LFS and see what they can make of it. We did a WC just Wednesday.

Link to comment

Came out slightly higher this time, but not much: 1060ppm or so I believe. We are going to do a WC and measure it again afterwards.

Link to comment

So there is a lot of missing information from you origianl post.

What is your testing method?

What are all you other parameters, Ca, Alk, pH, SG.......?

 

I would also test your newly mix ASW as the supplier gives what the final results should be. You can then compare yor test kits to what they say you should get at a specific gravity.

 

You should never add something unless you are also testing for it.

 

400 Ca is a fine number, as most reefers shoot for 420 ppm.

 

More info, meands more ability to help.

 

Good Luck!

Link to comment

So there is a lot of missing information from you origianl post.

What is your testing method?

What are all you other parameters, Ca, Alk, pH, SG.......?

 

I would also test your newly mix ASW as the supplier gives what the final results should be. You can then compare yor test kits to what they say you should get at a specific gravity.

 

You should never add something unless you are also testing for it.

 

400 Ca is a fine number, as most reefers shoot for 420 ppm.

 

More info, meands more ability to help.

 

Good Luck!

Thanks for the input!

 

Like I said we are using Salifert test kits, for Sg we are using a hydrometer.

I'll edit the OP too, but this is the info I have now.

 

Tank:

pH 7,7

Alk 9 - 10

Ca 425

Mg 1060

Sg 1.022

 

WC water (getting ready to do one now):

pH 8

Alk 7 - 8

Ca 400

Mg 1125

Sg 1.022

Link to comment

Do you keep your salinity at 1.022 on purpose? It's a little on the low side. If you mix salt at a higher salinity there will be a higher saturation of the elements.

Link to comment

Do you keep your salinity at 1.022 on purpose? It's a little on the low side. If you mix salt at a higher salinity there will be a higher saturation of the elements.

Thanks!

I see I made a typo in the other post, meant to say 1.022.

We thought we should be aiming for between 1.020 - 1.025?

What would you recommend?

 

~ Hester

Link to comment

I'd recommend around 1.025. Or 1.026 is you're keeping SPS. If you do raise it, do it slowly over your next few water changes so that you don't shock anything.

Link to comment

I'd recommend around 1.025. Or 1.026 is you're keeping SPS. If you do raise it, do it slowly over your next few water changes so that you don't shock anything.

We don't have SPS, so I think we'll go for 1.025 then. Thanks for the advice!

Link to comment

Archived

This topic is now archived and is closed to further replies.

  • Recommended Discussions

×
×
  • Create New...