Dosing Mag Wiped Out Fish Population

[adityaw]

So last night I dosed Kent's Tech M Mag into my tank. Using the calculator listed on http://reef.diesyst.com/flashcalc/flashcalc.html to bring my mag to 1280 from 1170, I dosed 44 tsp (1/2 of the required dose needed.)

My system volume is ~280L. Before the dosing here are some of the params:
Alk : 7.7
Mag: 1170
Cal: 360

Filtration : A skimmer rated for 700L, DSB, and that's it. (all in the sump)

This morning, after I found out that the only clownfish is lying dead on the sump, and the other 2 fishes (diadema and cleaner common wrasse) were missing (I assumed they are dead) I immediately did water test, here are the result:

Mag : 1200 (increase of 30PPM)
Nitrite : 0
Free Ammonia : 0
Nitrate : 10 (steady for the last 2 weeks with 10% weekly water change)
Phos : 0.25

Now, the tank is only 1 month old last Sunday. It's been through its cycle and passed its diatom bloom. Currently the tank is experiencing copepod bloom. Other than that the tank was cycled using Prodibio start up on day 1 and been dosed 2 bioptim and 1 biodigest ampules after the first week.

I don't have any idea what's happening in the tank right now. The corals looks normal, and all the inverts are alive (turbo snails, Debelius' Reef Lobster, and I haven't see the sand-sifting star yet.)

Did I dose my tank with Mg too fast? 1200 is not overdose right? What should I do now? Water change? What a sad morning

 

[RubberFrog]

You shouldn't have corals and fish in a one month old tank. And you really shouldn't be dosing ANYTHING at this point.

Water changes never hurt, especially with nitrates and phos that high. The truth is, anything could have killed those fish and the mag dose could just be coincidence.

 

[bertoni]

30 ppm of magnesium added shouldn't cause fish to die. I suspect the timing is a coincidence, but maybe the magnesium supplement got contaminated somehow.

 

[adityaw]

Found the diadema!

Found the diadema!

After creating the thread and before leaving for office I look at the tank once more and found the diadema!

I hope I can find the cleaner wrasse too and conclude that this event is coincidental.

@RubberFrog: Yeah I understand that I shouldn't put anything there but since the filter of my old tank cracked (inside the MT), I had to rebuild the tank. So I really had no choice to where to put the fish and corals. Thus the idea of using prodibio came up.

:beer:

 

[bertoni]

Okay, that sounds like good news!

 

[jbannick18]

One month old tank is fine for fish and corals

 

[Randy Holmes-Farley]

I agree that the Kent magnesium supplement nor magnesium itself should not be a concern at these levels. Many people use it for really big boosts to magnesium treating bryopsis and see no problems with fish.

 

[klondike4001]

What test were you using? Could it have been bad? Pushing Mg past 1700 can cause a die-off, but I will agree with the first few posters, at 1 month old for a reef, could have been several different reasons for the fish to die, and Mg of 1200 would not do that.

 

[Randy Holmes-Farley]

What test were you using? Could it have been bad? Pushing Mg past 1700 can cause a die-off, .

Die off of what?

 

[klondike4001]

I've read it can kill inverts.

 

[Sk8r]

44 tsp is quite a lot. I find it best to divide a large correction over the course of a week, allowing 8 hours for a dose to 'settle in'---then testing to see where that got me; and maybe adjusting the total if I find it's trending differently than I first thought. IANAC (I ain't no chemist!) but there are situations in which a bad test result can lead to a real high accumulation of something: in my situation I had an alk test go bad. It was reading low, and I kept pouring in buffer---and more and more buffer. I couldn't straighten it out. Then I realized the bad test problem---and had loaded my tank with SO much stuff that I had precipitated deposits in all my hoses and a coating all over my pump interior.

First be sure your test is accurate if the test gives you a strange reading and don't chase it until you're sure it's right. The things expire.

 

[Randy Holmes-Farley]

I've read it can kill inverts.

Maybe, but I do not recall seeing evidence of that at 1800 ppm.

FWIW, folks dosing a lot of a particular magnesium supplement might see problems due to impurities, not the magnesium.

 

[killarsox]

Maybe, but I do not recall seeing evidence of that at 1800 ppm.

FWIW, folks dosing a lot of a particular magnesium supplement might see problems due to impurities, not the magnesium.

Randy is it true that magnesium test kits are off on average of 80-100ppm?

I've got a buddy who swears by running his magnesium at 1700-1800. (well at least 1700-1800 ppm according to test kits) His tank looks amazing and the growth rate is amazing.

Do you think that these higher Mag levels contribute to the superior growth in anyway?

 

[Randy Holmes-Farley]

It seems there is substantial inaccuracy with magnesium kits in that many folks report changes that can only be due to testing errors, but some kits or some users might get pretty good results.

Higher magnesium might help coralline, but I've not heard it is any help to corals in general.

 

[adityaw]

What test were you using? Could it have been bad? Pushing Mg past 1700 can cause a die-off, but I will agree with the first few posters, at 1 month old for a reef, could have been several different reasons for the fish to die, and Mg of 1200 would not do that.

I'm using salifert. Are their mg test accurate?

44 tsp is quite a lot. I find it best to divide a large correction over the course of a week, allowing 8 hours for a dose to 'settle in'---then testing to see where that got me; and maybe adjusting the total if I find it's trending differently than I first thought. IANAC (I ain't no chemist!) but there are situations in which a bad test result can lead to a real high accumulation of something: in my situation I had an alk test go bad. It was reading low, and I kept pouring in buffer---and more and more buffer. I couldn't straighten it out. Then I realized the bad test problem---and had loaded my tank with SO much stuff that I had precipitated deposits in all my hoses and a coating all over my pump interior.

First be sure your test is accurate if the test gives you a strange reading and don't chase it until you're sure it's right. The things expire.

If I remember correctly, the instruction on the back of the bottle said to not dose more than 100ppm per day. Maybe if the dose was pure magnesium it should be okay, but as randy said there may be some impurities on the supplement.

It seems there is substantial inaccuracy with magnesium kits in that many folks report changes that can only be due to testing errors, but some kits or some users might get pretty good results.

Higher magnesium might help coralline, but I've not heard it is any help to corals in general.

The reason I dosed magnesium was to actually help increase my calcium. My alk and calc was on the low side, so I dose my tank with kalkwasser, however the calcium was having a hard time to get above 380. So I figure it might be caused by low mag. Is my approach correct?

Anyway, I've found the cleaner wrasse. And to be honest the clownfish was plagued with Lymphocystis from the last 2 weeks. From the information that I've read on the web, lymphocystis is not fatal at all. And the fish seemed eating and behaving normally the night before the event. So I'm not sure whether adding the 44tsp of the suplement had anything to do with this. My plan now is to add 11tsp of the suplement/day until reaching the recommended dose and test again. Thanks everyone for the feedbacks! I'm really happy to be able to learn from much more experienced reefers here

 

[disc1]

is it true that magnesium test kits are off on average of 80-100ppm?

I did substantially better than that with both Salifert and Seachem tests when I was playing around with the standard solutions. But then again, I have done a LOT of titrations in my lifetime.

I think there is a tendency, especially with magnesium kits, for people to over titrate them. There is a bit of an art to finding the end point. In the end, what you get is wide variation from user to user.

There is also a high importance on sample size. If your sample size is off by 10%, then that will create a 10% error at the end. Lots of kits have you measuring your sample with a 2ml or 5ml syringe. Those are not known to be particularly accurate instruments. There is usually a luer or tip on them, and the volume of that doesn't count. If it did, there wouldn't be a zero mark on the syringe. So when you draw the plunger up to the 2mL or 4mL mark or whatever, there should be a bubble in there that represents that tip volume. Then, make sure you get all of that into your sample cup. Don't leave a drop behind in the syringe.

Alternatively, you can fill the syringe with no bubble, but when you put the sample into the sample vessel you have to make sure you leave the tip full. I can't really pull that off nearly as easily as leaving the bubble and just making sure it all comes out.

 

[adityaw]

I did substantially better than that with both Salifert and Seachem tests when I was playing around with the standard solutions. But then again, I have done a LOT of titrations in my lifetime.

I think there is a tendency, especially with magnesium kits, for people to over titrate them. There is a bit of an art to finding the end point. In the end, what you get is wide variation from user to user.

There is also a high importance on sample size. If your sample size is off by 10%, then that will create a 10% error at the end. Lots of kits have you measuring your sample with a 2ml or 5ml syringe. Those are not known to be particularly accurate instruments. There is usually a luer or tip on them, and the volume of that doesn't count. If it did, there wouldn't be a zero mark on the syringe. So when you draw the plunger up to the 2mL or 4mL mark or whatever, there should be a bubble in there that represents that tip volume. Then, make sure you get all of that into your sample cup. Don't leave a drop behind in the syringe.

Alternatively, you can fill the syringe with no bubble, but when you put the sample into the sample vessel you have to make sure you leave the tip full. I can't really pull that off nearly as easily as leaving the bubble and just making sure it all comes out.

This has always been a big question in my head when drawing the water. Thanks for claring this up.

Also regarding test kits that changing color, let's say to blue .. do you stop when you see the color change or you keep titrating until you see solid blue (not violet)? I hope my question make sense.

 

[Randy Holmes-Farley]

The reason I dosed magnesium was to actually help increase my calcium. My alk and calc was on the low side, so I dose my tank with kalkwasser, however the calcium was having a hard time to get above 380. So I figure it might be caused by low mag. Is my approach correct?

I wouldn't first put the finger on magnesium issues.

You cannot use limewater (kalkwasser) to boost calcium substantially because alk will get too high, causing precipitation of calcium carbonate.

Use calcium chloride for a one time correction of calcium to the right levels, then use the kalkwasser to keep it and alkalinuty at that level.

 

[Randy Holmes-Farley]

FWIW, some people read the syringes in the Salifert kits backwards, so be sure you are reading it such that delivering a full syringe during the titration gives a decent magnesium value, rather than near zero.