Dosing Magnesium (Seems like it drops way more than Alk or Cal)

psychicmind

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Hello Reefers,

1) Why do I have to dose way more Magnesium compared to Alkalinity and Calcium?

2) What is the beast way to raise Magnesium in salt mix during storage (Red Sea Blue Bucket)?


My tank is a 5 gallon nano containing mostly LPS and a few softies. I plan to add SPS Montipora in the future.

I use Red Sea products, Blue Bucket Salt with liquid Magnesium, Alkalinity and Calcium for dosing.

Regarding Question One:

I have been testing Mag, Alk, and Cal with Salifert Text Kits daily.

I'm trying to figure out how much to dose and get an idea of what is going on.

My goal is to maintain 1350 Mag, 9 dKH Alk, and 440 Cal.

On average, I am having to daily dose 6 ml Magnesium, 1 ml Alkalinity, 0.3 ml Calcium.

It seems like a lot of Magnesium and dosing that much affects salinity.

It seems that Magnesium drops from 1350 to 1320 daily. This requires 6 ml of Magnesium to bring it back to 1350.

Why do I have to dose so much Magnesium? Is this normal? Or is something wrong?

Regarding Question Two:

Because of the above, I test my salt mix and try to raise it to my goal of 1350 Mag, 9 dKH Alk, and 440 Cal.

After mixing to 1.025 it tests at 1220 Mag, 8.5 dKH Alk, and 435 Cal

The very slight low level of Alk and Cal is not a problem.

But I would like to raise the Magnesium to 1350.

I premix my salt and store for up to a month (this is why I do not use Rea Sea Pro).

Using Res Sea liquid Magnesium to raise it takes a lot and I'm not sure it stays stable.

Is there a better way to raise Magnesium in salt mix for storage?

Right now I am manually dosing, but I would like to setup auto dosing once I get this figured out and stable.
 
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Sean Clark

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Testing Mg daily would be my first suspect. This interval if testing is far from necessary and is likely leading to your presumption of fluctuations. Mg should never deplete faster than Ca. A 10 to 1 ratio consumption of Ca to Mg has been well established. Add the lack of precision and consistency of hobby grade magnesium test and I think that you are chasing ghost that are not there. I would consider the variance of your test and then the importance of magnesium before I made any changes.
 
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psychicmind

psychicmind

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Testing Mg daily would be my first suspect. This interval if testing is far from necessary and is likely leading to your presumption of fluctuations. Mg should never deplete faster than Ca. A 10 to 1 ratio consumption of Ca to Mg has been well established. Add the lack of precision and consistency of hobby grade magnesium test and I think that you are chasing ghost that are not there. I would consider the variance of your test and then the importance of magnesium before I made any changes.

I do understand what you are saying. I also agree I might be chasing a ghost.

What throws me off is that once I test and get a reading of say 1320 and add 6 ml Red Sea Mag following instructions, then next test an hour later reads 1350. This has been consistent when testing.

Normally I test one a week. This tank is 3 months old, so I am testing twice weekly. Since I am trying to narrow down what my daily dosing should be, I have recently been testing daily. I am considering an auto doser, but my cal requirements don't seem to warrant that.

I am aware my mag should not be dropping fast than cal, so something is off.

More comments would be helpful, but skipping mag for now and focusing on Alk and Cal does make sense.
 
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Randy Holmes-Farley

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Magnesium consumption is not more than about 1/10th of the calcium consumption. Anything more is test error or a change in salinity. Real magnesium consumption is typically 0-2 ppm per day. There’s no special condition that makes it more.
 
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psychicmind

psychicmind

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I’ve been reading about this all day.

I am definitely chasing a ghost :)

I think for now I will just focus on Alk and Cal.

I already know I need 1.0 ml Alk and only 0.2 ml Cal daily. I don’t need an auto doser for that.

Based on Cal, I should only need 0.02 ml Mag which is not enought to worry about. That’s less than half a drop.

Red Sea Salt at 1220 Mag should be fine for now.

I’m a little concerned what my Mag levels really are now since I dosed a ton several times. Enough to raise salinity from 1.025 to 1.026. Should I be worried about that?
 

Randy Holmes-Farley

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I’ve been reading about this all day.

I am definitely chasing a ghost :)

I think for now I will just focus on Alk and Cal.

I already know I need 1.0 ml Alk and only 0.2 ml Cal daily. I don’t need an auto doser for that.

Based on Cal, I should only need 0.02 ml Mag which is not enought to worry about. That’s less than half a drop.

Red Sea Salt at 1220 Mag should be fine for now.

I’m a little concerned what my Mag levels really are now since I dosed a ton several times. Enough to raise salinity from 1.025 to 1.026. Should I be worried about that?

Do you know what the ppm amount of the magnesium dosing amounted to?
 
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psychicmind

psychicmind

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Do you know what the ppm amount of the magnesium dosing amounted to?

I’m not sure how to answer that.

I added 9 ml Red Sea Magnesium C liquid to 5 gallons tank water. My Salifert test kit said I started with 1320 ppm and then it tested to 1350 after dosing.

I did something similar to the salt mix before adding to the tank (in several water changes starting two weeks ago). 15 gallons fresh saltwater measured 1290 after mixing and I added 50 ml Red Sea Magnesium C liquid which then tested 1350 after. This water was in the tank today before I tested and dosed as outlined above.
 

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I am also using the red sea blue bucket and also using salifert. Salinity at 1.026 according to Milwaukee digital reader

I get 7.0 alk
1250 mag
420 cal

I am also manually dosing to bring my mag up slowly but it definitely does not go down faster than my calcium
 
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psychicmind

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I checked the PPM to the best of my ability.

Dosing 9 ml to 5 gallons should have raised it by 1.8 ppm.

To the salt mix made prior to water changes, adding 50 ml to 15 gallons would have raised it by 30 ppm
 
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psychicmind

psychicmind

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I am also using the red sea blue bucket and also using salifert. Salinity at 1.026 according to Milwaukee digital reader

I get 7.0 alk
1250 mag
420 cal

I am also manually dosing to bring my mag up slowly but it definitely does not go down faster than my calcium

Although I try to be very careful testing with Salifert so the results are accurate, the swings I’m seeing range between 1300 to 1350 in my tank and in just testing the Red Sea Blue Bucket after making fresh, 1240 two batches ago to 1290 this last batch. That is an averag difference of 50.

Maybe it is my test kit that is giving me these swings in readings.

So then maybe my magnesium in my tank is actually somewhere between 1300 and 1400 which should be OK?

I’m glad I’m asking here and getting this straightened out. Dosing 5.0 ml Mag a day and only 0.2 Cal sounds like a recipe for disaster.
 

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I think your fine in regard to your mag level. Hows your corals? 6ml of mag a day on a 5 gallon nano is quite a lot. Is your tank full of corals? I dose maybe half a mil every other day to bring it up slowly. and this is on a Red Sea 200XL 53gallon total volume. .5 mil of mag every other day on a 53 gallon tank with newly added corals 20 frags of mostly lps , softies.



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Lavey29

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Although I try to be very careful testing with Salifert so the results are accurate, the swings I’m seeing range between 1300 to 1350 in my tank and in just testing the Red Sea Blue Bucket after making fresh, 1240 two batches ago to 1290 this last batch. That is an averag difference of 50.

Maybe it is my test kit that is giving me these swings in readings.

So then maybe my magnesium in my tank is actually somewhere between 1300 and 1400 which should be OK?

I’m glad I’m asking here and getting this straightened out. Dosing 5.0 ml Mag a day and only 0.2 Cal sounds like a recipe for disaster.
A 3 month old 5 g nano tank with some LPS and softs should not require any dosing just simple water changes. You are throwing your balance completely off.
 
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Sean Clark

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What throws me off is that once I test and get a reading of say 1320 and add 6 ml Red Sea Mag following instructions, then next test an hour later reads 1350. This has been consistent when testing.

I added 9 ml Red Sea Magnesium C liquid to 5 gallons tank water. My Salifert test kit said I started with 1320 ppm and then it tested to 1350 after dosing.

15 gallons fresh saltwater measured 1290 after mixing and I added 50 ml Red Sea Magnesium C liquid which then tested 1350 after.

Dosing 9 ml to 5 gallons should have raised it by 1.8 ppm.
I think you have you answer right here. These dosing amounts are not consistent with your testing results.
First 6ml in 5 gallons gave you a 30ppm rise.
1ml=1ppm/gallon

Second 9ml in 5 gallons gave you a 30ppm rise. (I think one of these was a typo and it was either 6 or 9)
1ml=0.66ppm/gallon

Third 50ml in 15 gallons gave you a 60ppm rise.
1ml=0.08ppm/gallon

So if the dose of 9ml in 5 gallons should have raised it by 1.8ppm then the results you are seeing are just a combination of the resolution and accuracy of the test (if performed perfectly).
 
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psychicmind

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I think you have you answer right here. These dosing amounts are not consistent with your testing results.
First 6ml in 5 gallons gave you a 30ppm rise.
1ml=1ppm/gallon

Second 9ml in 5 gallons gave you a 30ppm rise. (I think one of these was a typo and it was either 6 or 9)
1ml=0.66ppm/gallon

Third 50ml in 15 gallons gave you a 60ppm rise.
1ml=0.08ppm/gallon

So if the dose of 9ml in 5 gallons should have raised it by 1.8ppm then the results you are seeing are just a combination of the resolution and accuracy of the test (if performed perfectly).

1 ml of Red Sea Magnesium C added to 25 gallons of saltwater raises magnesium 1 ppm. That’s from their website.

After checking the Salifert test kit, the difference between 1290 and 1350 is only 2 drops of reagent to get the color change. Plus sometimes it takes 2 drops to see a defined color change.

I think it is clear, it’s my test kit.

Thank you for helping me solve this mystery.

if anyone is judging me. That’s ok. I had saltwater fish only and reef tanks from 1990 to 2005. Then I stopped for 17 years until starting back up this year. The hobby has changed a ton since I started 25 years ago. I consider myself a total newbie and am learning all over again. Back then, we didn’t test or dose magnesium.

I purposely started with a 5 gallon nano because I know how hard it is to maintain stability. I figured it would be a great way to learn all over. It took me 3 weeks during the cycling period just to stabilize temp and salinity. Sounds crazy, but in the olden days I lived in a cold climate which required a heater. Now I live in the equatorial tropics. So I had to learn how to lower the temp. First I tried a temp controller to turn a fan on and off. That didn’t work well and created evaporation issues. Eventually I got a chiller and temp is stable between 78 to 79. At the same time salinity was up and down so I got an ATO which then stabilized it.

Even the cycling process is different now in 2022. Back in 1990, we threw in damsel fish or used raw shrimp. It was so much easier and faster to use Dr Tim’s Ammonia this time. Quarantining is different now too; observational, copper treatment, TTM hybrid. TTM hybrid seems to work best for me and is less stressful to the fish.

I say this because I’m not a total “dumb dumb” lol. I’m simply experimenting and learning about Mag, Alk, and Cal and how to maintain stability in a 5 gallon nano which is known to be more difficult. Now I know I don’t need an auto doser and there is not enough coral to warrant dosing Mag or Cal. I simply need to dose 1 ml Alk daily and water changes will take care of the rest.

I’m still working on keeping nitrate and phosphate low, not over feeding which is easy to do, and getting my skimmer functioning properly. I have not stabilized that yet.

Reef2Reef is a super awesome place for newbies to ask questions and learn from those more experienced.
 

gbroadbridge

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1 ml of Red Sea Magnesium C added to 25 gallons of saltwater raises magnesium 1 ppm. That’s from their website.

After checking the Salifert test kit, the difference between 1290 and 1350 is only 2 drops of reagent to get the color change. Plus sometimes it takes 2 drops to see a defined color change.

I think it is clear, it’s my test kit.
Just to be clear, the test kit is as accurate as any hobby grade test kit, so I wouldn't spend money trying to find something more accurate.

+/- 50ppm Mg almost makes no difference as long as you are around 1200-1400
 

Sean Clark

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1 ml of Red Sea Magnesium C added to 25 gallons of saltwater raises magnesium 1 ppm. That’s from their website.

After checking the Salifert test kit, the difference between 1290 and 1350 is only 2 drops of reagent to get the color change. Plus sometimes it takes 2 drops to see a defined color change.

I think it is clear, it’s my test kit.

Thank you for helping me solve this mystery.

if anyone is judging me. That’s ok. I had saltwater fish only and reef tanks from 1990 to 2005. Then I stopped for 17 years until starting back up this year. The hobby has changed a ton since I started 25 years ago. I consider myself a total newbie and am learning all over again. Back then, we didn’t test or dose magnesium.

I purposely started with a 5 gallon nano because I know how hard it is to maintain stability. I figured it would be a great way to learn all over. It took me 3 weeks during the cycling period just to stabilize temp and salinity. Sounds crazy, but in the olden days I lived in a cold climate which required a heater. Now I live in the equatorial tropics. So I had to learn how to lower the temp. First I tried a temp controller to turn a fan on and off. That didn’t work well and created evaporation issues. Eventually I got a chiller and temp is stable between 78 to 79. At the same time salinity was up and down so I got an ATO which then stabilized it.

Even the cycling process is different now in 2022. Back in 1990, we threw in damsel fish or used raw shrimp. It was so much easier and faster to use Dr Tim’s Ammonia this time. Quarantining is different now too; observational, copper treatment, TTM hybrid. TTM hybrid seems to work best for me and is less stressful to the fish.

I say this because I’m not a total “dumb dumb” lol. I’m simply experimenting and learning about Mag, Alk, and Cal and how to maintain stability in a 5 gallon nano which is known to be more difficult. Now I know I don’t need an auto doser and there is not enough coral to warrant dosing Mag or Cal. I simply need to dose 1 ml Alk daily and water changes will take care of the rest.

I’m still working on keeping nitrate and phosphate low, not over feeding which is easy to do, and getting my skimmer functioning properly. I have not stabilized that yet.

Reef2Reef is a super awesome place for newbies to ask questions and learn from those more experienced.
No one is judging. We are all here for the same goal.
 

92Miata

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A 3 month old 5 g nano tank with some LPS and softs should not require any dosing just simple water changes. You are throwing your balance completely off.
I very much disagree with this.

My IM10 was dropping more than 1/2 a dKH a day at 3 months. It doesn't take much growth to affect a small water volume like that.
 

Lavey29

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I very much disagree with this.

My IM10 was dropping more than 1/2 a dKH a day at 3 months. It doesn't take much growth to affect a small water volume like that.
All tanks are different but the majority consensus adheres to my recommendation so whatever floats your boat go for it. 3 month old tank should not even have coral in it yet or lights on.
 
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92Miata

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All tanks are different but the majority consensus adheres to my recommendation so whatever floats your boat go for it. 3 month old tank should not even have coral in it yet or lights on.
"majority consensus" means "made up" without data.


Water changes are a horrifyingly inefficient way to dose alkalinity. Dose what your tank needs. The early parts of the nitrogen cycle consume alkalinity.

A 3 month old reef tank can be a fully functioning reef tank if you stop doing things poorly. Like ignoring alkalinity usage.
 

gbru316

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A 3 month old 5 g nano tank with some LPS and softs should not require any dosing just simple water changes. You are throwing your balance completely off.

huh?

my 3 month old 40 breeder with a half dozen small SPS frags and 3-5 small LPS frags (all around an inch) consumes about 0.25 dKh per day. I’ve got no visible coralline growth and as they’re all relatively new (< 1 month) only 3 of my frags have noticeable growth.

if I left it go a week, it’d swing about 1.5 dKh. My 10% weekly water change only adds 0.8 dKh.

I went from dosing 5 ml/day of AF component 1, 2, 3 to dosing 30 mL/day in about 2 weeks. And rate of consumption has been increasing daily.
 
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