Compensate for the increase of salinity from dosing Magnesium?

Etoimos · 08/08/2018, 09:40 PM

I just started dosing Magnesium and it is raising my salinity. Should I be compensating for this increase in any way (removing saltwater and replacing with RODI?)?

Thanks,

Keith

Uncle99 · 08/09/2018, 06:30 AM

Yes, add RODI to keep salinity stable.
This increase is normal when adding larger amounts of MG, especially DIY powers, for some reason.
I assume your bringing MG up to around 1350 ish, then maintaining from there.
I have noticed no change in my salinity in my 70g. I use Seachem magnisum and it only takes 10ml per week to maintain 1350 ish...

bertoni · 08/09/2018, 12:15 PM

I agree that some RO/DI will solve the problem. I'd do that gradually, though. How high is the SG currently?

Etoimos · 08/09/2018, 02:09 PM

It's about 2ppt higher than what it normally is. Digging into it further, I don't think it is solely related to the dosing of Mag. It seems to have crept up slowly over a much longer time frame looking at the Apex logs.

Uncle99 · 08/09/2018, 02:19 PM

ATO will fix that and add great stability to this important parameter

outssider · 08/09/2018, 05:46 PM

dosing cal/alk/mag will increase salinity over time

bertoni · 08/09/2018, 09:23 PM

I agree that dosing a 2-part will increase alkalinity. 2 points up is a bit high, but I'd bring it down over a period of at least a few days, or maybe a week or so.

gargoylenest · 08/12/2018, 04:36 AM

I don't see how magnesium, calcium or alkalinity would raise "salinity". I can understand that it can raise "gravity" or "conductivity" (our affordable means of measurement), but not chloride and sodium? Going from this principle, since only gravity and conductivity is changing due to the addition of metal (mg) to the water, should you realy care about adjusting your salt level, or you are only risking changing actual "salinity" level by trying to adjust "gravity"...

bertoni · 08/12/2018, 03:19 PM

The supplements usually are made of calcium chloride, magnesium chloride, and sodium carbonate or bicarbonate. The corals consume the calcium, magnesium, and carbonate, and leave the sodium and chloride in the tank. The effect can be measurable very quickly in a tank with a lot of calcification. A month is plenty of time.

rvareef · 08/12/2018, 03:31 PM

what kind of mag supplement are you dosing?

08/08/2018, 09:40 PM	#1
Etoimos Registered Member Join Date: Mar 2017 Posts: 161	Compensate for the increase of salinity from dosing Magnesium? I just started dosing Magnesium and it is raising my salinity. Should I be compensating for this increase in any way (removing saltwater and replacing with RODI?)? Thanks, Keith

08/09/2018, 12:15 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I agree that some RO/DI will solve the problem. I'd do that gradually, though. How high is the SG currently? __________________ Jonathan Bertoni

08/09/2018, 05:46 PM	#6
outssider Registered Member Join Date: Nov 2009 Location: Reseda, Ca. Posts: 1,717	dosing cal/alk/mag will increase salinity over time __________________ Please don't feed the bears because the bears will become dependent on free handouts and forget how to take care of themselves …... Current Tank Info: 75 Gal. Mixed reef mostly sps

08/09/2018, 09:23 PM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I agree that dosing a 2-part will increase alkalinity. 2 points up is a bit high, but I'd bring it down over a period of at least a few days, or maybe a week or so. __________________ Jonathan Bertoni

08/12/2018, 03:19 PM	#9
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The supplements usually are made of calcium chloride, magnesium chloride, and sodium carbonate or bicarbonate. The corals consume the calcium, magnesium, and carbonate, and leave the sodium and chloride in the tank. The effect can be measurable very quickly in a tank with a lot of calcification. A month is plenty of time. __________________ Jonathan Bertoni

08/09/2018, 06:30 AM	#2
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	Yes, add RODI to keep salinity stable. This increase is normal when adding larger amounts of MG, especially DIY powers, for some reason. I assume your bringing MG up to around 1350 ish, then maintaining from there. I have noticed no change in my salinity in my 70g. I use Seachem magnisum and it only takes 10ml per week to maintain 1350 ish...

08/09/2018, 02:09 PM	#4
Etoimos Registered Member Join Date: Mar 2017 Posts: 161	It's about 2ppt higher than what it normally is. Digging into it further, I don't think it is solely related to the dosing of Mag. It seems to have crept up slowly over a much longer time frame looking at the Apex logs.

08/09/2018, 02:19 PM	#5
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	ATO will fix that and add great stability to this important parameter

08/12/2018, 04:36 AM	#8
gargoylenest Registered Member Join Date: Jan 2015 Location: montreal,canada Posts: 135	I don't see how magnesium, calcium or alkalinity would raise "salinity". I can understand that it can raise "gravity" or "conductivity" (our affordable means of measurement), but not chloride and sodium? Going from this principle, since only gravity and conductivity is changing due to the addition of metal (mg) to the water, should you realy care about adjusting your salt level, or you are only risking changing actual "salinity" level by trying to adjust "gravity"...

08/12/2018, 03:31 PM	#10
rvareef In Memoriam Join Date: Jun 2014 Posts: 664	what kind of mag supplement are you dosing?