Dosing 2-part - Are Magnesium Swings Normal?

[bzb]

I've started dosing BRS 2-part to try to get my levels stable. I'm testing just about every day, especially Alk, and I'm getting unstable readings on Magnesium. Alk and Calcium seem to have stabilized from the dosing, but I'm sure both will drop (or increase?) again with the magnesium issue.

I test everything at least twice to make sure I'm counting correctly.

Is this normal - especially the rapid drop in Mg? I haven't done a water change since I began adjusting/dosing.



Test kits are:
- Hanna pH checker.
- Salifert and Rikka for Ca and Mg. Both of these come out to be within 10-15% of each other in readings.
- Salifert and Hanna for Alk. Within .5 of each other in dkh.
- Giesemann for Nitrate, Seachem for Phosphate.

Tank is approx 5 months old. No visible coralline growth. Bit of GHA on the gyre, but otherwise fairly nuisance-free.

 

[civics14]

that is some serious drops with your current system. are you doing water changes between those test? mg usually don't get used that much in my experience.

 

[fidofence1]

Are you dosing Magnesium as well? It looks like you need to dose to get it back up but as long as calcium and Alk are staying steady magnesium isn’t real important. Also I would increase your nitrates


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[gill]

I am doing 2 part for a year now, and my mg never moves at all. Cal a little, and Alk drops like crazy if I do not supplement.

 

[bzb]

that is some serious drops with your current system. are you doing water changes between those test? mg usually don't get used that much in my experience.

Haven't done a water change since 12/8. Been trying to figure out how much my tank is consuming to start dosing pumps. But that's proven... difficult to figure out

 

[bzb]

Are you dosing Magnesium as well? It looks like you need to dose to get it back up but as long as calcium and Alk are staying steady magnesium isn’t real important. Also I would increase your nitrates


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Yes - I dosed Mg 600mL the first day I got the BRS kit, then 300 mL the next day to get it above my target.

As far as Nitrates and Phos, Jin suggested I do the same... I'm scared. The crazy thing (at least, crazy to me) is that I feed this tank an incredible amount for just 4 juvenile fish.

I think you guys would freak out how much if I were honest.

 

[civics14]

Yes - I dosed Mg 600mL the first day I got the BRS kit, then 300 mL the next day to get it above my target.

As far as Nitrates and Phos, Jin suggested I do the same... I'm scared. The crazy thing (at least, crazy to me) is that I feed this tank an incredible amount for just 4 juvenile fish.

I think you guys would freak out how much if I were honest.

lol - you should see how much I feed my tank, but then again I can't get my nitrates to go below 15ppm.

Regarding your mg - I'm stumped. are you seeing in precipitation on your equipment?

 

[bzb]

No precip from what I can tell and the equipment all seems fine. In fact, the skimmer is running the best it ever has after the cleaning I gave a few weeks ago.

I still have zero noticeable coralline growth. Softies are reproducing and growing. LPS/SPS seem to have pretty good polyp extension.

 

[Adam]

I've never used the Rikka tests. I do use Salifert for Mag and it's been the most reliable for me. Seeing swings like that are probably due to user testing irregularities. Try to maintain the exact same procedure for each test. Even then these are hobbiest test kits expect to see 3-5% variance between tests and no two different kits report the exact same results.

Mag is one of the highest element concentrations in our tanks and doesn't fluctuate quickly without outside manipulation. Being water changes or manual addition.

 

[bzb]

I've never used the Rikka tests. I do use Salifert for Mag and it's been the most reliable for me. Seeing swings like that are probably due to user testing irregularities. Try to maintain the exact same procedure for each test. Even then these are hobbiest test kits expect to see 3-5% variance between tests and no two different kits report the exact same results.

Mag is one of the highest element concentrations in our tanks and doesn't fluctuate quickly without outside manipulation. Being water changes or manual addition.

To be clear: I don’t want to be chasing numbers. But I’m testing everything multiple times and the whack-a-mole game of these numbers is getting frustrating!

It seems to be a steady decline, but it just seems way too much to be accurate. I just don’t understand where the Mg is going, unless it’s precipitating out somewhere that’s not evident to me.

 

[ichthyoid]

If you are saying the Mg was 1350 on 12/8 & dropped to 1056 on 12/13, that’s a 22% drop in 5 days. Is that correct?

If so, something is amiss & I would suspect the test kit. Take samples of your water to your LFS for verification.

 

[bzb]

That’s correct, and why it’s concerning me. I’ve got two Magnesium test kits, and they’re both saying my Mg has dropped.

 

[Dmitri]

If your mag dropped and you have verified with two different test kits, just manually dose corrective amount to increase it. BRS has a calculator for that on their website.

Also remember if you are doing corrective dosing for magnesium, it may be necessary to spread the dose out throughout multiple days to avoid raising the magnesium level more than 100ppm per day.

 

[ichthyoid]

Have you added any new corals, sand or rock?
If not, then I’m thinking your coraline growth has taken off. It can sink quite a bit of Mg when growing fast.

 

[ichthyoid]

I did a quick search and found this post by RHF -

 

[ichthyoid]

Here’s the r2r thread, from above. RHF does a great job explaining why Mg doesn’t drop fast -

why does my magnesium drop?

hey guys this is my first post on here. i always watch the vivd aquariums videos on youtube and i enjoy everyone of them. but i have been having little problem with my water parameters. im currently doing the red sea coral growth program and following their recommended water parameters. and it...

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[Adam]

I agree. There's only two ways the mag dropped that much so quick. #1 is testing error or bad kit. #2 is dilution via salt water removal and top off water added to refill, which would correspond with a salinity drop.

Taking in a sample to a LFS or to another member for verification would be a good idea. I'm in Flowery Branch and can test it for you anytime.

 

[bzb]

I am having considerable evaporation, but nothing that has dropped salinity. Skimmer is pulling out approximately 2 cups each week - again, nothing that's dropping salinity that much.

I suppose it's my testing procedure *shrug*. Going to see if I can get my water tested today - but even after that, I'm not sure what I'll be doing going forward for dosing if I can't get consistent readings from my own kits.

 

[Shawn]

I hate that all of the magnesium tests are titration tests. That's why I love using Hannah checkers otherwise. Digital readings and easy to use reagents = less room for error. I did magnesium tests for the first time last night - and that's a pain in the rear for sure. And on top of all of that I'm colorblind... sigh

 

[Adam]

I'm colorblind too. I need my wife or someone else around to do Mag and a couple other tests.

There are a few apps out there that help some, like Aquarium Note. But it's no help for the Mag test