Constant low magnesium… any advice?

[Miemaes]

Hi all,

I’ve been noticing low magnesium in both of my tanks (6g and 33g). I’ve been dosing magnesium to get it to 1350 ppm… but every time I do a waterchange it drops again. First I used reef crystals salt and just recently I switched to Red sea blue bucket. I never used a power head to mix the salt and always stirred it manually like the basic person I am . I read that you have to stir it for at least 30 min but no longer then 4 hours. Today I did another water change (with wave maker in the bucket) and my magnesium dropped again to 1275 ppm. Am I doing something wrong? Am I missing something?… Any feedback or personal experiences are more then welcome

 

[jackson6745]

My blue buckets mix to 1200mg. What does yours mix to? Probably pulling down the levels. Always use a powerhead to dissolve salt.

 

[Miemaes]

My blue buckets mix to 1200mg. What does yours mix to? Probably pulling down the levels. Always use a powerhead to dissolve salt.

My blue buckets mix to 1200mg. What does yours mix to? Probably pulling down the levels. Always use a powerhead to dissolve salt.

I’m guessing it’s close to that number because I try to keep mine at 1350. I will keep using a powerhead from now on but I don’t get why it mixes lower then the numbers displayed on the bucket. All the rest is fine.

 

[jackson6745]

I’m guessing it’s close to that number because I try to keep mine at 1350. I will keep using a powerhead from now on but I don’t get why it mixes lower then the numbers displayed on the bucket. All the rest is fine.

It's not going to hurt anything at 1200 but a small MG addition each water change should keep it in check. Also, keep in mind that MG level is also dependent on salinity. 1200 is what I get at 35ppt/1.026. If you run a lower salinity the MG will be a little lower.

 

[besskurz]

I had something similar.
I tested, tested and tested.
Wc after wc, always under 900.
I could not believe. Everything was fine.

My issue was:
ME.

I have the redsea test kits for Mg.
I was reading the values upside-down.
Instead of reading how many liquid was left in the syringe, I was supposed to count how many reagent I used.

Instead of 3.2 which is 700ish mg.
It is 6.8 ish = 1360mg

If salinity and kh are fine.
WC's are done.
I would narrow the possibilities to a incorrect reading or bad / expired reagents.

That's my two cents after going thru this during the weekend and willing to punch myself.

 

[gbroadbridge]

Hi all,

I’ve been noticing low magnesium in both of my tanks (6g and 33g). I’ve been dosing magnesium to get it to 1350 ppm… but every time I do a waterchange it drops again. First I used reef crystals salt and just recently I switched to Red sea blue bucket. I never used a power head to mix the salt and always stirred it manually like the basic person I am . I read that you have to stir it for at least 30 min but no longer then 4 hours. Today I did another water change (with wave maker in the bucket) and my magnesium dropped again to 1275 ppm. Am I doing something wrong? Am I missing something?… Any feedback or personal experiences are more then welcome

I'd say you have a measurement error and should just ignore it.

You really do not need to test magnesium.

Let's say your tank is 1350 and your water change is 1200. That is a difference of 150ppm.

If you change 10% of water in your tank, you will be dropping the magnesium by 10% of 150, so it will drop by 15ppm i.e. 1350 to 1335.

There is no hobby magnesium test kit that can give you any better than about 30-50ppm accuracy, so that difference cannot be measured by you.

Additionally, ocean is around 1200 and nothing in the tank cares less whether it is 1200 or 1500.
Under about 1150 you may end up with chemistry issues but that won't happen.

Ignore it... And throw the Mg test kit away - unless you like doing tests for fun.

 

[taricha]

This is why Randy started advocating not testing Mg, but instead using a trusted salt, getting your salinity right, and doing a normal amount of water changes.
Under that scenario, Mg can't get far enough off to matter.
https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

 

[Randy Holmes-Farley Verified Community Expert]

Hi all,

I’ve been noticing low magnesium in both of my tanks (6g and 33g). I’ve been dosing magnesium to get it to 1350 ppm… but every time I do a waterchange it drops again. First I used reef crystals salt and just recently I switched to Red sea blue bucket. I never used a power head to mix the salt and always stirred it manually like the basic person I am . I read that you have to stir it for at least 30 min but no longer then 4 hours. Today I did another water change (with wave maker in the bucket) and my magnesium dropped again to 1275 ppm. Am I doing something wrong? Am I missing something?… Any feedback or personal experiences are more then welcome

These rapid changes are test error.

My suggstion is to ignore magneisum for the moment.

Can you describe the aquaria themselves and how you are maintaining alkalinity?