Just say NO to magnesium testing: RMM is born

[Randy Holmes-Farley]

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing.

I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good methods need a catchy name.

Here it is.

1. NEVER measure magnesium. If it comes free from an ICP, sure, take a look. It's probably fine anyway. Don't buy or use a kit. Chances are the results are not very reliable, and most of the time, if there is a value out of the range of acceptable, it is more likely an error of some sort than a real result.

2. Use a decent salt mix at a decent salinity that has a starting level of magnesium and calcium that you like. If you cannot find one, it is easy to add a fixed amount of magnesium to a salt mix. I did that for many years, and rarely measured the tank itself.

3. ANY time that you add calcium, add 5-10% as much magnesium (so for 10 ppm calcium, add 0.5 - 1 ppm magnesium). If coralline is the main user of alk in your tank, use the 10%, if corals are, use 5%. A lot of products, like commercial two parts, AFR, CaCO3/CO2 reactors with suitable media, and my DIY two part systems all add magnesium for you, without measurement.

4. It will take a very long time for any sort of significant deviation to show, and if you also do water changes, it likely never will.

To some this will sound like a joke, but I think many reefers, especially newer reefers, would be better served by RMM than testing and retesting, dosing and redosing and then getting a new kit and testing again. Just a few minutes ago I finished a thread where a kit change gave a 200 ppm difference in magnesium.

Just say no. Exact magnesium levels are just not that important.

 

[Vailj123]

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing.

I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good methods need a catchy name.

Here it is.

1. NEVER measure magnesium. If it comes free from an ICP, sure, take a look. It's probably fine anyway. Don't buy or use a kit. Chances are the results are not very reliable, and most of the time, if there is a value out of the range of acceptable, it is more likely an error of some sort than a real result.

2. Use a decent salt mix at a decent salinity that has a starting level of magnesium and calcium that you like. If you cannot find one, it is easy to add a fixed amount of magnesium to a salt mix. I did that for many years, and rarely measured the tank itself.

3. ANY time that you add calcium, add 5-10% as much magnesium (so for 10 ppm calcium, add 0.5 - 1 ppm magnesium). If coralline is the main user of alk in your tank, use the 10%, if corals are, use 5%. A lot of products, like commercial two parts, AFR, CaCO3/CO2 reactors with suitable media, and my DIY two part systems all add magnesium for you, without measurement.

4. It will take a very long time for any sort of significant deviation to show, and if you also do water changes, it likely never will.

To some this will sound like a joke, but I think many reefers, especially newer reefers, would be better served by RMM than testing and retesting, dosing and redosing and then getting a new kit and testing again. Just a few minutes ago I finished a thread where a kit change gave a 200 ppm difference in magnesium.

Just say no. Exact magnesium levels are just not that important.

I like it lol

 

[Miami Reef]

I like this method. I hate testing magnesium.

 

[Battlecorals]

Works for me!

 

[Borat]

I am generally against any form testing - every time you test something that something changes. However I noticed that if I don't test at all, it does not change!

 

[14 foot reef]

@Randy Holmes-Farley
This is the best method I've ever read for testing mg. Its the most time consuming, most inaccurate test in the hobby. What a relief you have given to so many reefers. Brilliant Randy !!!!!
I do not know 1 person who looks forward to magnesium testing !!!!!

 

[hexcolor reef]

Reef Advantage Calcium also has 17mg of magnesium. If you have a coralline algae and lots of it boosting maybe needed if you have LPS dominant tank

 

[hexcolor reef]

@Randy Holmes-Farley
This is the best method I've ever read for testing mg. Its the most time consuming, most inaccurate test in the hobby. What a relief you have given to so many reefers. Brilliant Randy !!!!!
I do not know 1 person who looks forward to magnesium testing !!!!!

You don’t have to test magnesium as frequently as you would test calcium/alk
Dosing by hand could be more of problem but if you have dosing pumps it’s less of a bother as you know magnesium is in its range without needing to test

 

[Alexraptor]

Actually sounds rather sensible, especially considering how extremely toxic some of the magnesium test reagents are.

 

[Kraig]

I've always had higher Magnesium. My (home) test results ALWAYS shows above 1500, somewhere between 1500-1600.

I've had 2 ICP tests in the last year, one about a year ago at 1394 and one the end of this past August shows 1470. I contribute my higher Magnesium to the FritzPro salt that I use (states 1425 Magnesium mixed to 35ppm). I do not dose Magnesium.

I've wondered if higher Magnesium levels in my tank can lead to ill effects on the corals (I don't have that many right now) but wasn't sure if I should do anything about it or not.

I've also wondered why my tests at home with both a Red Sea Pro Magnesium test kit and a Salifert test kit both always showing above 1500.

think this post convinces me to just forget about testing Magnesium at home and just adjust if I need to after ICP tests.

 

[rtparty]

It has been a VERY long time since I cared one bit about magneisum. As long as it is around 1300 or more, I never care. My tank has pretty good coral coverage and growth going on and yet, I haven't dosed magnesium specifically in the 20 months it has been up. My tank gets magnesium mainly from water changes and Tropic Marin Part C. Part C has very little but seems to be plenty to keep up with my tank.

 

[gfox]

Sounds like a good idea.One less test to have to do.I never tested it anyways.

 

[SliceGolfer]

I test Mag once per month. In the past year, I found two times the value was not my preferred number. Was it grossly out of balance? No, not in the least. Off by 20 points. I'm onboard with this line of thinking.

I dose Kalkwasser in the evenings and have found the same to be true with Calcium. Test it once per month, it's always at 440-460. It's another "Why bother testing" element for me.

 

[thatmanMIKEson]

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing.

I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good methods need a catchy name.

Here it is.

1. NEVER measure magnesium. If it comes free from an ICP, sure, take a look. It's probably fine anyway. Don't buy or use a kit. Chances are the results are not very reliable, and most of the time, if there is a value out of the range of acceptable, it is more likely an error of some sort than a real result.

2. Use a decent salt mix at a decent salinity that has a starting level of magnesium and calcium that you like. If you cannot find one, it is easy to add a fixed amount of magnesium to a salt mix. I did that for many years, and rarely measured the tank itself.

3. ANY time that you add calcium, add 5-10% as much magnesium (so for 10 ppm calcium, add 0.5 - 1 ppm magnesium). If coralline is the main user of alk in your tank, use the 10%, if corals are, use 5%. A lot of products, like commercial two parts, AFR, CaCO3/CO2 reactors with suitable media, and my DIY two part systems all add magnesium for you, without measurement.

4. It will take a very long time for any sort of significant deviation to show, and if you also do water changes, it likely never will.

To some this will sound like a joke, but I think many reefers, especially newer reefers, would be better served by RMM than testing and retesting, dosing and redosing and then getting a new kit and testing again. Just a few minutes ago I finished a thread where a kit change gave a 200 ppm difference in magnesium.

Just say no. Exact magnesium levels are just not that important.

are you selling any RMM test kits?

 

[Randy Holmes-Farley]

are you selling any RMM test kits?

Absolutely.

They are best kept on a shelf next to pet rocks.

 

[Notsolostfish]

What about those people who says lps prefer 1500 mag? Is that not true? As a new reefer i hear it all the time

 

[trmiv]

Pretty much my experience. Only mag testing I do is because my trident does it, but otherwise I never would. I have never supplemented magnesium on my tank and never seen the point to doing so because I do water changes.

 

[thatmanMIKEson]

What about those people who says lps prefer 1500 mag? Is that not true? As a new reefer i hear it all the time

(imo) all that elevated elements is just a sales tactic and Unnecessary use of material, probably started by the ones selling the additives..

but yes this is heard all the time.

 

[Snoopy 67]

What would you consider a good range for magnesium?

 

[YOYOYOReefer]

I’ve always used magnesium in my calcium reactor, i used to run separate calcium and magnesium reactors but I found just putting the top 2-3 inches with ma medium in my calcium reactor works and only need 1 reactor.