Huge MG drop after water change

[Javierati]

Chemistry question:

My CA++ and MG have been running on the high end for a few months now. I haven't been dosing CA++ or MG and was just waiting it out until the corals consume these to normal levels.

Suddenly last week the MG dropped 90ppm in a single day. It coincided with a water change. I don't personally do the water change as I have the aquarium specialist come and do it for me. He states that he is using Red Sea Coral Pro Salt.

7/30/2021
MG 1429
CA 540
ALK 8.77
ORP 210

7/31/2021
MG 1338
CA 522
ALK 8.85
ORP 89

Salinity has remained stable at 34.5-35.5

After this sudden drop, the MG & CA has remained stable while the ALK has been rising slowly to 9.2 (on purpose, dosing soda-ash).

This also coincided with a sudden drop in ORP. The drop in ORP remained for 1.5 days and then slowly started to rise to the current level of 240.

The chemistry question comes in the backdrop of me trying to identify a particular reason why my euphylia corals are less vivid and happy as before. Some tentacles are smaller, darker. Others are closed. I am thinking that this sudden change caused stress to these corals.

I have been spot feeding more often reef roids and using restor by brightwell to see if this helps during this stressful period.

Any advice would be helpful. Thanks!

 

[MnFish1]

Chemistry question:

My CA++ and MG have been running on the high end for a few months now. I haven't been dosing CA++ or MG and was just waiting it out until the corals consume these to normal levels.

Suddenly last week the MG dropped 90ppm in a single day. It coincided with a water change. I don't personally do the water change as I have the aquarium specialist come and do it for me. He states that he is using Red Sea Coral Pro Salt.

7/30/2021
MG 1429
CA 540
ALK 8.77
ORP 2010

7/31/2021
MG 1338
CA 522
ALK 8.85
ORP 89

Salinity has remained stable at 34.5-35.5

After this sudden drop, the MG & CA has remained stable while the ALK has been rising slowly to 9.2 (on purpose, dosing soda-ash).

This also coincided with a sudden drop in ORP. The drop in ORP remained for 1.5 days and then slowly started to rise to the current level of 240.

The chemistry question comes in the backdrop of me trying to identify a particular reason why my euphylia corals are less vivid and happy as before. Some tentacles are smaller, darker. Others are closed. I am thinking that this sudden change caused stress to these corals.

I have been spot feeding more often reef roids and using restor by brightwell to see if this helps during this stressful period.

Any advice would be helpful. Thanks!

The 'drop' in Mg may be within the variability of the test (depending on which one you are using). And since it seems stable now - is likely due to the water change.

The drop in Mg was very very small (lets say 1 percent) - that would not affect corals, etc. If the Mg in the new salt was somewhat lower - depending on how much water was changed - this is probably the reason.

For various reasons ORP drops with chemical changes - and it would be impossible to figure out exactly 'why'. An ORP of 2010 is extremely HIGH (unbelievably high) - and 89 is unbelievably low. i.e. - I wouldn't make anything out of it - except to check your probe for dirt, algae, etc - which can make the ORP seem extremely high. (I.e. those results do not make sense)

To answer further - it would be helpful to know - how often you do water changes, what size tank, how much water was changed, was the temperature of the water carefully matched, the salt mixed properly, etc.

I do not see anything hugely significant in your tests - or a significant 'change'. Hope this helps

 

[Javierati]

The 'drop' in Mg may be within the variability of the test (depending on which one you are using). And since it seems stable now - is likely due to the water change.

The drop in Mg was very very small (lets say 1 percent) - that would not affect corals, etc. If the Mg in the new salt was somewhat lower - depending on how much water was changed - this is probably the reason.

For various reasons ORP drops with chemical changes - and it would be impossible to figure out exactly 'why'. An ORP of 2010 is extremely HIGH (unbelievably high) - and 89 is unbelievably low. i.e. - I wouldn't make anything out of it - except to check your probe for dirt, algae, etc - which can make the ORP seem extremely high. (I.e. those results do not make sense)

To answer further - it would be helpful to know - how often you do water changes, what size tank, how much water was changed, was the temperature of the water carefully matched, the salt mixed properly, etc.

I do not see anything hugely significant in your tests - or a significant 'change'. Hope this helps

Thanks for the reply;
Had a typo on the ORP. It was 210 and not 2010. So the drop was from 210 to 89. My ORP usually runs at 240-270 range.

My tank is 450 gallon, with temps ranging from 77.5-78.5. Usually it changes by 1 degree up and down twice a day.

Water changes are done weekly at 25 gallons per water change.

How salt is mixed, I would need to ask my aquarium guy.

I know that water temp of the new water going in is not matched before introducing it to the tank. It will likely be hotter; low 90's

 

[MnFish1]

Thanks for the reply;
Had a typo on the ORP. It was 210 and not 2010. So the drop was from 210 to 89. My ORP usually runs at 240-270 range.

My tank is 450 gallon, with temps ranging from 77.5-78.5. Usually it changes by 1 degree up and down twice a day.

Water changes are done weekly at 25 gallons per water change.

How salt is mixed, I would need to ask my aquarium guy.

I know that water temp of the new water going in is not matched before introducing it to the tank. It will likely be hotter; low 90's

To me - it seems like the drops/changes in some of your parameters are basically in line with the amount of water changed. I do not know how to reconcile the changes you're seeing with your corals with the water change. ORP is notoriously fickle - and I ignore it completely

 

[Spieg]

Any advice would be helpful. Thanks!

My advise is to manage your hobby yourself. Can't even imagine hiring someone to take care of my tank.

 

[Javierati]

My advise is to manage your hobby yourself. Can't even imagine hiring someone to take care of my tank.

I have been considering this strongly over the past 3 weeks. It is an added stress to not know things like: "how is the salt mixed", "what temperature is the added water at", etc etc.