What would cause Mg to increase

FireEMT · Sep 2, 2016

I have had my tank up and running now since December 2015. Every month since starting my dosing of BRS Soda Ash and Calcium, my Mg has increased over the month until I do the water change. I don't add any Mg and the calcium steadily increases until I do the water change and then it returns to 1400. What would cause it to increase, I use a new Red Sea test kit. I dose around 59ml of Alk and Cal a day and they stay very steady.

stevo01 · Sep 2, 2016

Something is blocking the Mg from being absorbed? I know calcium and magnesium tie in closely. I forget the exact chemistry on it. Corals don't absorb calcium if the magnesium level isn't high enough. Maybe the calcium level isn't high enough so the magnesium is being absorbed... That's a guess tho.

Randy Holmes-Farley · Sep 2, 2016

How much does it increase?

Is salinity increasing?

What water to replace evaporation?

FireEMT · Sep 2, 2016

Randy Holmes-Farley said:
How much does it increase?

Is salinity increasing?

What water to replace evaporation?

All other parameters stay very solid. RODI water top off automatically

FireEMT · Sep 2, 2016

Randy Holmes-Farley said:
How much does it increase?

Is salinity increasing?

What water to replace evaporation?

The Mg usually increases from 1400 to 1600 over the month.

FireEMT · Sep 2, 2016

The only other things I have been adding is NOPOX daily and the two part has Fauna Marin balling light trace 1,2, &3 added to it. I am going to stop the trace 1,2,3 and switch to red sea energy a & b because my tank has 0 no3 and po4 and my corals show it.

Piranhapat · Sep 2, 2016

What salt are you using?

Randy Holmes-Farley · Sep 2, 2016

Balling light does add some magnesium, I believe. Perhaps you mixed it up wrong?

Or it might just be testing error. How many times has this happened?

FireEMT · Sep 2, 2016

It has happened ever month and ever time I test. I add 10 ml of 1 and 2 to the calcium and 20 ml of 3 to the Alk solution. Its a total guessing game because they only give the numbers for their own salt. The fauna marin really hasn't made a difference but the week or so adding the Energy A and B has made a drastic difference especially in the gonipora. I have never been able to get any NO3 or PO4 so I think the coral are starving. I feed only frozen LRS so the tank stays clean and only have 5 fish in 120ish gallons.

FireEMT · Sep 2, 2016

Piranhapat said:
What salt are you using?

I use HW Marine Reefer salt

rock_lobster · Sep 2, 2016

Thats a lot of magnesium assuming your tank isnt a nano. My best guess would be testing error or something that is causing your test to read inaccurately. You couldnt add that much in additives or food over a month. Maybe if your topoff water somehow were loaded with magnesium not the case if your testing and the ppm is somewhat low.

rock_lobster · Sep 2, 2016

I would try a different test kit.

FireEMT · Sep 2, 2016

rock_lobster said:
Thats a lot of magnesium assuming your tank isnt a nano. My best guess would be testing error or something that is causing your test to read inaccurately. You couldnt add that much in additives or food over a month. Maybe if your topoff water somehow were loaded with magnesium not the case if your testing and the ppm is somewhat low.

I've never tested the parameters of the RODI water but its a newer system 150GPD BRS unit and the TDS meter reads 1 coming from the RO membrane and 0 coming out of the first DI resin.

FireEMT · Sep 2, 2016

rock_lobster said:
I would try a different test kit.

When I tested the HWMarine Reefer it comes in right where the manufacture specs are and thats tested with the same Red Sea kit. Maybe I need to grab something different though. The test for Mg is the biggest pain because you have to mix 15 sec between each drop of part A. I try to be very precise while testing, I'm kind of anal that way.

rock_lobster · Sep 2, 2016

FireEMT said:
I've never tested the parameters of the RODI water but its a newer system 150GPD BRS unit and the TDS meter reads 1 coming from the RO membrane and 0 coming out of the first DI resin.

Thats all the testing needed to be done. the PPM would be like 1000+ if it were loading your tank up with magnesium.

rock_lobster · Sep 2, 2016

FireEMT said:
When I tested the HWMarine Reefer it comes in right where the manufacture specs are and thats tested with the same Red Sea kit. Maybe I need to grab something different though. The test for Mg is the biggest pain because you have to mix 15 sec between each drop of part A. I try to be very precise while testing, I'm kind of anal that way.

Yea I would still try another test before going any further. Try salifert testing can be completed in less than a minute.

Randy Holmes-Farley · Sep 2, 2016

I don't see an actual reason it would rise either and I too think testing error is most likely, or accidently using the wrong solution for supplementing.

stevo01 · Sep 2, 2016

Randy Holmes-Farley said:
I don't see an actual reason it would rise either and I too think testing error is most likely, or accidently using the wrong solution for supplementing.

To what degree are Mg readings effected by salinity?

Randy Holmes-Farley · Sep 2, 2016

stevo01 said:
To what degree are Mg readings effected by salinity?

Same as everything else (except pH and ORP): directly.

So a jump from sg = 1.204 to 1.026 will result in an 8.3% increase in magnesium, say from 1290 to 1400 ppm.