Magnesium levels constantly steady???

[Mppp]

I dose Alk & Calc daily, but never have had to adjust or dose magnesium. I've searched the forum and can only conclude by somewhat of a guess that magnesium does not deplete as rapidly as long as small biweekly water changes are being completed. Anyone else find dosing Mg is of smaller proportions than Alk/Ca or maybe never have to bother dosing it at all? (Alk 8.7-9 Ca 400 and I'm using Redsea test kits).

 

[jcates]

I'll check it at least monthly going forward. I recently checked mine after don't remember how long if I'm being honest. And it was at 1100. And causing sps to fade in color. It takes a lot of material to get it back up in a 180 and commitment to spread that dose over days. Always done weekly WC before but switched to AWC a month ago.

 

[jcates]

But I had seen on BRS YouTube, I think, where it says water changes would basically keep that up so I would expect if you check it regularly it would be small doses

 

[Randy Holmes-Farley Verified Community Expert]

Magnesium depletion is too slow to detect by kit in a week or less. Usually it is no more than 1/10th of the calcium depletion rate. Usually 1 ppm per day or less.

 

[ID-Reefer]

I have a 240 gal system and do about 3 gal. water change/day with AWC. I run apex and trident so tests are performed several times a day. I dose two part with DOS and at the moment am adding about 95ml for alkalinity 70 ml. for calcium per day.

My Magnesium stays consistent around 1300 and I never have to dose anything. Like you I assumed my small water changes have kept Mg where it needs to be but do wonder since I see others dosing Mg.

 

[Randy Holmes-Farley Verified Community Expert]

I have a 240 gal system and do about 3 gal. water change/day with AWC. I run apex and trident so tests are performed several times a day. I dose two part with DOS and at the moment am adding about 95ml for alkalinity 70 ml. for calcium per day.

My Magnesium stays consistent around 1300 and I never have to dose anything. Like you I assumed my small water changes have kept Mg where it needs to be but do wonder since I see others dosing Mg.

If you are dosing calcium and alkalinity as separate solutions, I'd still dose the Part 3 at the prescribed rate because it does more than just maintain magnesium. It also maintains the chloride to sulfate ratio. I do not recommend dosing the part 3 based on measurements of magnesium.

The added dosing may not noticeably impact the magnesium, but, IMO, should still be done. Folks using commercial two parts and/or Balling are doing the exact same thing, but just are not basing the magnesium dose on magnesium testing since it is part of the other solutions.

 

[ID-Reefer]

If you are dosing calcium and alkalinity as separate solutions, I'd still dose the Part 3 at the prescribed rate because it does more than just maintain magnesium. It also maintains the chloride to sulfate ratio. I do not recommend dosing the part 3 based on measurements of magnesium.

The added dosing may not noticeably impact the magnesium, but, IMO, should still be done. Folks using commercial two parts and/or Balling are doing the exact same thing, but just are not basing the magnesium dose on magnesium testing since it is part of the other solutions.

Thanks for the response Randy. I guess this just further exemplifies my ignorance in reef chemistry. Im using the BRS DIY 2 part with Mg. I have a mixed up gallon of the Mg mix but was not adding since my Mg was within suggested perameters. So, if I'm not dosing based on MG testing how much are you suggesting I add? What is the ratio I should be using?


I just found your post that states this:

I'd recommend dosing the recommended amount: 610 ml of the magnesium part over the course of adding 1 gallon of the alk or calcium part. Or 1 ml of the magneisum part for each 6 mL of the alk or calcium part.

So I guess thats my answer?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the response Randy. I guess this just further exemplifies my ignorance in reef chemistry. I have a mixed up gallon of the Mg mix but was not adding since my Mg was within suggested perameters. So, if I'm not dosing based on MG testing how much are you suggesting I add? What is the ratio I should be using?

Assuming this is my DIY (as from BRS), and you are using sodium carbonate (not sodium bicarbonate) you dose 610 mL of part 3 per gallon of the alk part used. So its dosed at 16% of the alk part.

Is it a big deal? Likely not. But since you have it, I'd use it.

 

[ID-Reefer]

Assuming this is my DIY (as from BRS), and you are using sodium carbonate (not sodium bicarbonate) you dose 610 mL of part 3 per gallon of the alk part used. So its dosed at 16% of the alk part.

Is it a big deal? Likely not. But since you have it, I'd use it.

Randy,
Just a follow up to this. Yes it’s the DIY BRS system. Per your suggestion I started dosing 16% Mg. My Mg has just slightly increased from about 1290 to 1310. My alk however over a 5 day period has started dropping so I’ve upped my dosing from 85 ml to 120 ml in order to keep my alk at or near my typical 8.7. I’m testing with Hanna and apex. Ca has been stable around 410 with no dosing amount change.
Does the increased amount of sodium carbonate needed because of dosing 16% Mg make sense to you? Is that something you would expect to happen?

 

[Randy Holmes-Farley Verified Community Expert]

Randy,
Just a follow up to this. Yes it’s the DIY BRS system. Per your suggestion I started dosing 16% Mg. My Mg has just slightly increased from about 1290 to 1310. My alk however over a 5 day period has started dropping so I’ve upped my dosing from 85 ml to 120 ml in order to keep my alk at or near my typical 8.7. I’m testing with Hanna and apex. Ca has been stable around 410 with no dosing amount change.
Does the increased amount of sodium carbonate needed because of dosing 16% Mg make sense to you? Is that something you would expect to happen?

I expect it is coincidence as that magnesium increase is pretty small.