Question on mag dosing.

AquaAdam · 04/17/2018, 07:37 AM

I've been watching my parameters and my magnesium seems to drop 15-20ppm per day. I currently use red sea's abc foundation to dose but they say the max daily increase is only 10ppm for magnesium. So, just wondering what my options are since, in order to stabilize my tank on a daily basis, I would be adding more than the recommended dosage.

Thanks!

mcgyvr · 04/17/2018, 08:13 AM

Yes.. as stated its rather confusing..
OBVIOUSLY if your parameters are swinging more than that daily you need to dose more than that..

Its really saying don't let your mag swing/change by more than 10ppm per day..
Just like don't let your alk swing by more than 1dkh per day..
Its really their "recommended" maximum daily change and when it exceeds that you should start dosing.. So because you are losing 15-20ppm a day you should have already been dosing before you got to 10ppm drop..

You are dosing to prevent that swing/change from happening in the future..

If you want to stick with their recommendation then you can start by dosing 10ppm today and tomorrow your swing is only 5-10ppm and then you can add on the extra 10ppm so that you aren't swinging by more than 10 at one time..
Going forward you are replenishing what is being removed so your net swing is zero even though you might be dosing 20ppm the real daily increase is a net zero..

hkgar · 04/17/2018, 11:44 AM

A drop of 15-20 for Mag seems rather excessive. My mag doesn't move that much in a week or more.

How large is the tank? What are your levels for Alk and calcium? How much are they changing daily.

hbrochs · 04/17/2018, 01:47 PM

I never have to dose Mg and my tank has a bunch of SPS and LPS. I dose Alk and Ca, and the Magnesium stays in range with just regular water changes. Is there a chance this is just testing error? Mg typically has to be brought up when you first set up the tank, but after that I think its unlikely that its truly dropping that fast. There is some inherent bias when we test. You have an expectation that you are trying to verify with the test, and that can color your reading of the result. You could take a sample to the local fish store and get a base line, and then bring them another sample in three or four weeks and compare.

Phixman · 04/17/2018, 03:24 PM

How many days consecutively have you tested? It could be just the margin of error.

Phixman · 04/17/2018, 04:24 PM

Here is mine for comparison, mine always drops during a water change, so I just do 25%, and another 25% the next day so I don't get big swings, I dose 30ish ml of Mag to keep Mag in check during the first water change to prevent swings as well. As you can see from the image my mag has been stable all week, the last test looks to be a drop, but it's just the ME.

bertoni · 04/17/2018, 10:36 PM

I agree that 10-15 ppm per day seems like a huge amount of magnesium consumption. What are the calcium and alkalinity consumption rates.

AquaAdam · 04/18/2018, 06:41 AM

Hello and thank-you for the replies.

mcgyver - Thanks for clarifying that for me. That's what my ultimate goal is - replenishing what is being removed so your net swing is zero even though you might be dosing 20ppm the real daily increase is a net zero..

hkgar - Tank is a 60 cube with 15gal sump - Other levels are usually good. my calcium doesn't drop too much - I didnt have time to check the levels yesterday but I will tonight - and my Alk stays pretty stable. Yesterday it was 8 but I try to keep it at 8.3-8.4.

hbrochs- I don't think it is a testing error. My mag has always dropped rather quickly. I believe it might be due to the live rock I have inside the tank. Whatever kind it is, it seems to eat it up. I do have coral as well but not too much just a couple frogspawn, birdsnest, zoas, and some shrooms at the moment. I'm going to take your advice on having someone else check the levels and take it to a lfs near me one day this week just to verify test results.

Phixman - I didn't know you could monitor Mag on the apex. I don't have one but I definitely want one, as it would be alot easier to visually see the drop on a graph than through test kits. Now all I need is a couple thousand.....

hkgar · 04/18/2018, 09:32 AM

Quote:

Originally Posted by AquaAdam

Phixman - I didn't know you could monitor Mag on the apex. I don't have one but I definitely want one, as it would be alot easier to visually see the drop on a graph than through test kits. Now all I need is a couple thousand.....

Apex does not monitor Mag. The graph is created by posting the results from your testing.

Tripod1404 · 04/18/2018, 10:37 AM

Wow that is very unusual. Biologic consumption of Mg is mainly by coraline algae and even they only have about 4.4-4.5% skeletal weight by Mg.

So the expected Mg consumption of coralline with respect to alk is around 4.4 ppm magnesium for each 2.7 dKH of alkalinity, or 1.6 ppm for each 1 dKH. So a swing of 10-15ppm Mg needs an alk consumption of 7-10 dKH per day.

I think you either have a bad test that gives wildly inconsistent numbers or there is an abiotic reaction going on.

AquaAdam · 04/18/2018, 09:45 PM

Apex does not monitor Mag. The graph is created by posting the results from your testing. - So thats through their app, and you just type in your numbers?

Tripod1404 - I'm fairly certain I purchased a new test kit a while back as I was wondering the same thing then, but got the same results. I'm going to take my water in to have someone else test it and compare. what is an Abiotic reaction?

Tripod1404 · 04/19/2018, 09:54 AM

@AquaAdam , abiotic means there is a non-biological process that consumes Mg.

AquaAdam · 04/19/2018, 10:39 AM

So here are my test results today. I'm going to be taking my water to get tested but just wanted to post them. I'll update once I have the other results.

Salinity 1.024
Mg - 1230 - I let it go for a couple days to try to calculate loss/day according to red sea
Ca - 464 - no issues here really
dkh - 8.1 - I dosed 3 days ago so this tells me I'm loosing .1ppm/day

I'm using a salifert test kit for the mg thats good until end of 2019, so I don't think it's the kit.

Sk8r · 04/19/2018, 11:16 AM

What puzzles me is a drop in alk while the mg is testing over 1200. Do you have some Salifert test kits you can use to doublecheck that alk and cal as well as mg? I'm wondering if those tests are accurate. If your alk is down, that could answer for some screwiness. Also that cal is quite high. If alk and cal get screwed up, it can deposit in your pipes and hoses and such.

bertoni · 04/19/2018, 10:05 PM

If the magnesium is forming magnesium carbonate somehow, that'd explain the drop in both levels. We'd need a chart of measurements for the three parameters and dosing quantities to say much, though.

AquaAdam · 04/20/2018, 09:37 AM

So in store they tested for mg and it came in at 1200; so even lower than my test kit. (Both were salifert) I bought another salifert mg test kit yesterday so I am going to test with the brand new one today, as well as the old and compare results. From what I understand the majority of people are using salifert test kits to test for mg. Is there a better test kit out there, thats reasonably priced? I dont think hanna makes one..

bertoni · 04/20/2018, 09:49 AM

The Salifert kit has been fine, in my experience, but any kit can fail. I'm not sure what's happening here, but a few days of measurement might give us a good trend line. If you could test at the same time for a bit, that might help a bit, but the results in theory should be stable.

04/17/2018, 07:37 AM	#1
AquaAdam Registered Member Join Date: Mar 2016 Location: Ontario Posts: 95	Question on mag dosing. I've been watching my parameters and my magnesium seems to drop 15-20ppm per day. I currently use red sea's abc foundation to dose but they say the max daily increase is only 10ppm for magnesium. So, just wondering what my options are since, in order to stabilize my tank on a daily basis, I would be adding more than the recommended dosage. Thanks!

04/17/2018, 08:13 AM	#2
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	Yes.. as stated its rather confusing.. OBVIOUSLY if your parameters are swinging more than that daily you need to dose more than that.. Its really saying don't let your mag swing/change by more than 10ppm per day.. Just like don't let your alk swing by more than 1dkh per day.. Its really their "recommended" maximum daily change and when it exceeds that you should start dosing.. So because you are losing 15-20ppm a day you should have already been dosing before you got to 10ppm drop.. You are dosing to prevent that swing/change from happening in the future.. If you want to stick with their recommendation then you can start by dosing 10ppm today and tomorrow your swing is only 5-10ppm and then you can add on the extra 10ppm so that you aren't swinging by more than 10 at one time.. Going forward you are replenishing what is being removed so your net swing is zero even though you might be dosing 20ppm the real daily increase is a net zero.. __________________ Who me?

04/17/2018, 11:44 AM	#3
hkgar Registered Member Join Date: Oct 2002 Location: Dewitt MI Posts: 5,051	A drop of 15-20 for Mag seems rather excessive. My mag doesn't move that much in a week or more. How large is the tank? What are your levels for Alk and calcium? How much are they changing daily. __________________ Gary 180 gallon, 40 gallon sump, 3 250 W MH + 4 80W ATI T5's, MTC MVX 36 Skimmer, Apex controller Aquamaxx T-3 CaRx Current Tank Info: A 2 Barred Rabbitfish, Red Head Salon, Yellow/Purple, McMaster Fairy, Possum, 2 Leopard Wrasses, Kole, & Atlantic Blue Tangs, 2 Percula Clown, 3 PJ and 1 Banggai Cardinalfish , Swallowtail, Bellus and Coral Beauty Angels

04/17/2018, 01:47 PM	#4
hbrochs Registered Member Join Date: Oct 2014 Location: Westchester, NY Posts: 439	I never have to dose Mg and my tank has a bunch of SPS and LPS. I dose Alk and Ca, and the Magnesium stays in range with just regular water changes. Is there a chance this is just testing error? Mg typically has to be brought up when you first set up the tank, but after that I think its unlikely that its truly dropping that fast. There is some inherent bias when we test. You have an expectation that you are trying to verify with the test, and that can color your reading of the result. You could take a sample to the local fish store and get a base line, and then bring them another sample in three or four weeks and compare. __________________ 80 Gallon Innovative Marine long shallow reef 30 Gallon tank for raising baby clownfish Current Tank Info: Innovative Marine SR-80

04/17/2018, 10:36 PM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I agree that 10-15 ppm per day seems like a huge amount of magnesium consumption. What are the calcium and alkalinity consumption rates. __________________ Jonathan Bertoni

04/17/2018, 03:24 PM	#5
Phixman Registered Member Join Date: Jan 2017 Location: Lynnwood, WA Posts: 176	How many days consecutively have you tested? It could be just the margin of error.

04/17/2018, 04:24 PM	#6
Phixman Registered Member Join Date: Jan 2017 Location: Lynnwood, WA Posts: 176	Here is mine for comparison, mine always drops during a water change, so I just do 25%, and another 25% the next day so I don't get big swings, I dose 30ish ml of Mag to keep Mag in check during the first water change to prevent swings as well. As you can see from the image my mag has been stable all week, the last test looks to be a drop, but it's just the ME.

04/18/2018, 06:41 AM	#8
AquaAdam Registered Member Join Date: Mar 2016 Location: Ontario Posts: 95	Hello and thank-you for the replies. mcgyver - Thanks for clarifying that for me. That's what my ultimate goal is - replenishing what is being removed so your net swing is zero even though you might be dosing 20ppm the real daily increase is a net zero.. hkgar - Tank is a 60 cube with 15gal sump - Other levels are usually good. my calcium doesn't drop too much - I didnt have time to check the levels yesterday but I will tonight - and my Alk stays pretty stable. Yesterday it was 8 but I try to keep it at 8.3-8.4. hbrochs- I don't think it is a testing error. My mag has always dropped rather quickly. I believe it might be due to the live rock I have inside the tank. Whatever kind it is, it seems to eat it up. I do have coral as well but not too much just a couple frogspawn, birdsnest, zoas, and some shrooms at the moment. I'm going to take your advice on having someone else check the levels and take it to a lfs near me one day this week just to verify test results. Phixman - I didn't know you could monitor Mag on the apex. I don't have one but I definitely want one, as it would be alot easier to visually see the drop on a graph than through test kits. Now all I need is a couple thousand.....

04/18/2018, 10:37 AM	#10
Tripod1404 Registered Member Join Date: Mar 2016 Posts: 1,821	Wow that is very unusual. Biologic consumption of Mg is mainly by coraline algae and even they only have about 4.4-4.5% skeletal weight by Mg. So the expected Mg consumption of coralline with respect to alk is around 4.4 ppm magnesium for each 2.7 dKH of alkalinity, or 1.6 ppm for each 1 dKH. So a swing of 10-15ppm Mg needs an alk consumption of 7-10 dKH per day. I think you either have a bad test that gives wildly inconsistent numbers or there is an abiotic reaction going on.

04/18/2018, 09:45 PM	#11
AquaAdam Registered Member Join Date: Mar 2016 Location: Ontario Posts: 95	Apex does not monitor Mag. The graph is created by posting the results from your testing. - So thats through their app, and you just type in your numbers? Tripod1404 - I'm fairly certain I purchased a new test kit a while back as I was wondering the same thing then, but got the same results. I'm going to take my water in to have someone else test it and compare. what is an Abiotic reaction?

04/19/2018, 09:54 AM	#12
Tripod1404 Registered Member Join Date: Mar 2016 Posts: 1,821	@AquaAdam , abiotic means there is a non-biological process that consumes Mg.

04/19/2018, 10:39 AM	#13
AquaAdam Registered Member Join Date: Mar 2016 Location: Ontario Posts: 95	So here are my test results today. I'm going to be taking my water to get tested but just wanted to post them. I'll update once I have the other results. Salinity 1.024 Mg - 1230 - I let it go for a couple days to try to calculate loss/day according to red sea Ca - 464 - no issues here really dkh - 8.1 - I dosed 3 days ago so this tells me I'm loosing .1ppm/day I'm using a salifert test kit for the mg thats good until end of 2019, so I don't think it's the kit.

04/19/2018, 11:16 AM	#14
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	What puzzles me is a drop in alk while the mg is testing over 1200. Do you have some Salifert test kits you can use to doublecheck that alk and cal as well as mg? I'm wondering if those tests are accurate. If your alk is down, that could answer for some screwiness. Also that cal is quite high. If alk and cal get screwed up, it can deposit in your pipes and hoses and such. __________________ Sk8r Salinity 1.024-6; alkalinity 8.3-9.3 on KH scale; calcium 420; magnesium 1300, temp 78-80, nitrate .2. Ammonia 0. No filters: lps tank. Alk and cal won't rise if mg is low. Current Tank Info: 105g AquaVim wedge, yellow tang, sailfin blenny,royal gramma, ocellaris clown pair, yellow watchman, 100 microceriths, 25 tiny hermits, a 4" conch, 1" nassarius, recovering from 2 year hiatus with daily water change of 10%.

04/19/2018, 10:05 PM	#15
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	If the magnesium is forming magnesium carbonate somehow, that'd explain the drop in both levels. We'd need a chart of measurements for the three parameters and dosing quantities to say much, though. __________________ Jonathan Bertoni

04/20/2018, 09:37 AM	#16
AquaAdam Registered Member Join Date: Mar 2016 Location: Ontario Posts: 95	So in store they tested for mg and it came in at 1200; so even lower than my test kit. (Both were salifert) I bought another salifert mg test kit yesterday so I am going to test with the brand new one today, as well as the old and compare results. From what I understand the majority of people are using salifert test kits to test for mg. Is there a better test kit out there, thats reasonably priced? I dont think hanna makes one..

04/20/2018, 09:49 AM	#17
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The Salifert kit has been fine, in my experience, but any kit can fail. I'm not sure what's happening here, but a few days of measurement might give us a good trend line. If you could test at the same time for a bit, that might help a bit, but the results in theory should be stable. __________________ Jonathan Bertoni