Magnesium not dropping

dodgy67 · 12/29/2016, 04:30 PM

I raised my mag levels about two months ago in both my tanks (a 60gall and 20gall) to just over 1600 to help combat some algae problems using Magnesium Chloride Hexahydrate and Epsom Salts, both tanks are now joined together corals are thriving, 10 large clumps of Halimda, I dose Kalkwasser using a ph meter and Bicarbonate of Soda to maintain Ca and Alk..

Mag is still testing over 1600, any ideas why this is not depleting over this two month time period

Tank 1 60gall
Tank 2 25gall
Sump 25gall
ph 8.4 - 8.5
Alk 10-11
Salinity 1.025
Nitrate 0.0
Phosphate 0.02

Sk8r · 12/29/2016, 04:45 PM

Oceanic salt, eg, has a very high mg content. Take a look at your salt mix and see if it's just naturally high: if nothing is using it up and you're continuing to do water changes with high mg salt, it can be real hard to change. I switched to Instant Ocean because of this problem.

dodgy67 · 12/29/2016, 04:59 PM

Sk8r not done a water change in two months only a small top up due to salt creep loss when sal dropped to 1.023

bertoni · 12/29/2016, 08:09 PM

Magnesium often is consumed in very small amounts. My tanks never required magnesium supplementation due to consumption, although they ran for more than 10 years. 1600 ppm probably is safe enough, but you probably would need to do water changes with a lower-magnesium product to drop the level in any reasonable time frame.

tmann51 · 05/20/2019, 10:54 AM

A few months ago I checked my magnesium levels and found them to be low. I started adding BRS mag for two part dosing and monitoring the levels. I'd been using Salifert test that was not expired. I switched to Red Sea magnesium test and discovered my adjusted levels to be off the scale, over 1600! All my water pumps are regularly locking up and my Osmolator also malfunction. I'm also having to dose large amounts of calcium and alkalinity daily. 20 percent water changes weekly have not moved to readable levels. Any help would be appreciated. I'm using Red Sea Pro salt currently.

bertoni · 05/20/2019, 10:27 PM

You probably can get a reading by using two syringes for the final titration, and adding the results. I'd increase the water change rate, if that's not too much work or cost. To cause that kind of problem, I'd expect the magnesium to be extremely high. What is the magnesium level in the freshly-mixed saltwater?

12/29/2016, 04:30 PM	#1
dodgy67 Dave Join Date: Dec 2014 Location: Leighton Buzzard UK Posts: 122	Magnesium not dropping I raised my mag levels about two months ago in both my tanks (a 60gall and 20gall) to just over 1600 to help combat some algae problems using Magnesium Chloride Hexahydrate and Epsom Salts, both tanks are now joined together corals are thriving, 10 large clumps of Halimda, I dose Kalkwasser using a ph meter and Bicarbonate of Soda to maintain Ca and Alk.. Mag is still testing over 1600, any ideas why this is not depleting over this two month time period Tank 1 60gall Tank 2 25gall Sump 25gall ph 8.4 - 8.5 Alk 10-11 Salinity 1.025 Nitrate 0.0 Phosphate 0.02

12/29/2016, 04:45 PM	#2
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	Oceanic salt, eg, has a very high mg content. Take a look at your salt mix and see if it's just naturally high: if nothing is using it up and you're continuing to do water changes with high mg salt, it can be real hard to change. I switched to Instant Ocean because of this problem. __________________ 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%.

12/29/2016, 04:59 PM	#3
dodgy67 Dave Join Date: Dec 2014 Location: Leighton Buzzard UK Posts: 122	Magnesium not dropping Sk8r not done a water change in two months only a small top up due to salt creep loss when sal dropped to 1.023

12/29/2016, 08:09 PM	#4
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	Magnesium often is consumed in very small amounts. My tanks never required magnesium supplementation due to consumption, although they ran for more than 10 years. 1600 ppm probably is safe enough, but you probably would need to do water changes with a lower-magnesium product to drop the level in any reasonable time frame. __________________ Jonathan Bertoni

05/20/2019, 10:54 AM	#5
tmann51 Registered Member Join Date: Jul 2008 Location: Wisconsin Posts: 8	Un readable magnesium levels A few months ago I checked my magnesium levels and found them to be low. I started adding BRS mag for two part dosing and monitoring the levels. I'd been using Salifert test that was not expired. I switched to Red Sea magnesium test and discovered my adjusted levels to be off the scale, over 1600! All my water pumps are regularly locking up and my Osmolator also malfunction. I'm also having to dose large amounts of calcium and alkalinity daily. 20 percent water changes weekly have not moved to readable levels. Any help would be appreciated. I'm using Red Sea Pro salt currently.

05/20/2019, 10:27 PM	#6
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	You probably can get a reading by using two syringes for the final titration, and adding the results. I'd increase the water change rate, if that's not too much work or cost. To cause that kind of problem, I'd expect the magnesium to be extremely high. What is the magnesium level in the freshly-mixed saltwater? __________________ Jonathan Bertoni