Magnesium difference for tank upgrade

[UnnamedReef]

Hey everyone, upgrading my Aqueon 55 to a Planet 120. Current setup is a mixed reef mostly comprised of torches, Duncans, zoas, GSP, chalices, gorgonians, cyphastrea, and leathers. 6 or 7 smaller fish, peppermint shrimp, various snails.

Over the past few weeks I've been slowly adjusting the 120 parameters to match the 55 gallon. I went a bit heavy on the magnesium add at the end, because it's IO and I run my mag higher for my torches I needed to does up.

Salinity matches at 1.025. temp matches at 79.

Alk is 8.6 in the 120 vs 8.5 in the 55 gallon
Calc is 423 in the 120 vs 430 in the 55 gallon
Mag is 1584 in the 120 vs 1423 in the 55 gallon

All measured with API to get close, then tweaked with my trident. Same trident for both tank tests.

I'm wondering if I need to do a couple water changes to bring my mag back closer to the 55 or let it ride. I'd rather not waste the salt and RODI water if I don't have to. I moved my GSP over as a trial and the whole mat opened right up and is happy. I'm thinking my torches may be more sensitive to the +140 mag increase, though.

 

[bushdoc]

I would start with more accurate test kit, like Salifert.

 

[UnnamedReef]

Is a trident considered inaccurate for magnesium? Mine has always been very consistent and responded to dosing as expected so I've trusted the results for years.

 

[obanarama]

I just completed a hot-swap upgrade from a 75g to a 180g and the mag in the 180g was about 200 less (1400 vs 1200) in the 180g. My torches didn't care at all and opened right up in the new tank. Though I did increase my mag to 1400 over the course of a few days after the upgrade. Its 8 days later now and all corals still very happy.

 

[UnnamedReef]

That's good to know, thanks! I'm not super worried about it but wanted to get others testimonials before I do the transfer

 

[obanarama]

Is a trident considered inaccurate for magnesium? Mine has always been very consistent and responded to dosing as expected so I've trusted the results for years.

I don't believe any of our hobby-grade tests measure magnesium with much consistency. The test results fluctuate no matter the test kit. However, my trident is VERY good at charting magnesium trends over time after I calibrate it to my manual Red Sea foundation magnesium test results. In the end I just try to keep my mag high enough so that I don't cause a precipitation event with calcium dosing. The corals just don't seem to care what that number is.

 

[UnnamedReef]

That's fair, I really use mine for trends rather than trusting the value within X amount. Mine is consistent test to test, around 3 ppm so I trust it for a differential measurement like this transfer. Doesn't necessarily matter what the value is, just how it compares to the new tank to me

 

[Reeferbadness]

Interesting way to look at the whole magnesium thing from @Randy Holmes-Farley https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

 

[Randy Holmes-Farley]

Do you know that you added that much (a massive amount) or are you going by a test result that is reasonably likely to be inaccurate?

 

[UnnamedReef]

I know that I added a ton. My IO mix used to keep me around 1200 and I used Magnesion to bring it up to 1400+ in my 55 gallon. I knew it took a lot to dose up so I added quite a bit in the 120, too much apparently.

Reading the article I'm comfortable with the tank transfer, at least I won't need to dose magnesium for a looooong time