# Too much Mg in tank?



## hbosman (Oct 5, 2006)

You could always do a 50 % water change and see if they look happier. 50 ppm isn't much at all but maybe you could increase it in smaller, more gradual steps.


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## Seattle_Aquarist (Jun 15, 2008)

Hi gray fox,

The recommended level for Mg in a planted tank is 2 - 5 ppm. You have 10-20 times the recommended level. I am not familiar with Mg overdose symptoms, but if it were my tank I would be doing 50% water changes daily for the next several days.

BTW, plants grow best if the proper Ca:Mg ratio is maintained. Did you also add extra Ca? Excessive Mg may effect the uptake of other nutrients and result in reduced plant growth.


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## gray_fox (May 9, 2011)

I will do a 50% water change when i get home....cant hurt anything besides screw up my dosing schedule. I don't add anything extra for Ca. I have very hard water, so i have never added Ca. Just Mg... The water straight out of the tap is 0ppm Mg...So i just started to dose it a few days ago....I have a 125 gallon tank...I put about 2.5 tablespoons of Mg in.. I thought the proper levels of Mg was supposed to be 50-100 ppm...????


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## happi (Dec 18, 2009)

how did you add the Mg in your tank, how many Tsp etc. plants don't need that much Mg, 10ppm of Mg is enough for heavy planted tank. adding too much Mg does help fight the algae IMO.


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## gray_fox (May 9, 2011)

I was told to use epsomsalt. I was told to put in about 3 tablespoons. I mix it in a bucket of water then once it's desolved, I pour slowly into tank.


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## Seattle_Aquarist (Jun 15, 2008)

Hi gray fox,

What did you use as your Mg source? If it was Epsom Salt (MgSO4*7 H2O) then 2.5 level tablespoons should result in a Mg level of about 10ppm (assuming 100 gallons of water in your 125 gallon tank).

I don't know where you got 50 - 100 ppm Mg as the recommended level. I like the APC Fertilator to help determine target ppm levels that the ppm level that should result from dosing.

If it were me, I would re-test again when I got home and do an H2O change if the levels are still high.


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## gray_fox (May 9, 2011)

Ok, i will double check the levels when i get home and go from there... I will probably end up changing the water again..bleh. Just took out 50% last night since its been awhile since i last changed it :/ Just hope the fishies aren't dead. Ill flip if i killed my piranhas! They were just started to show signs of breeding!


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## happi (Dec 18, 2009)

gray_fox said:


> Ok, i will double check the levels when i get home and go from there... I will probably end up changing the water again..bleh. Just took out 50% last night since its been awhile since i last changed it :/ Just hope the fishies aren't dead. Ill flip if i killed my piranhas! They were just started to show signs of breeding!



do the water change, if possible do 70% water change and don't add any Mg this time. in your next water change add Mg, in my 50g i add 1 table spoon every water change, which gives around 7ppm of Mg.


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## Hoppy (Dec 24, 2005)

Seattle_Aquarist said:


> Hi gray fox,
> 
> The recommended level for Mg in a planted tank is 2 - 5 ppm. You have 10-20 times the recommended level. I am not familiar with Mg overdose symptoms, but if it were my tank I would be doing 50% water changes daily for the next several days.
> 
> BTW, plants grow best if the proper Ca:Mg ratio is maintained. Did you also add extra Ca? Excessive Mg may effect the uptake of other nutrients and result in reduced plant growth.


How did you arrive at 2-5 ppm as the recommended level of Mg in a planted tank? If you have 4X that in calcium, or 8-20 ppm, you only have around 1 degree of GH, which is pretty low. I would expect that the recommended amount of Mg would be in the 50 ppm area. Also, I don't recall seeing that a ratio between calcium and magnesium is significant for aquatic plants.


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## Seattle_Aquarist (Jun 15, 2008)

Hi Hoppy,

Because our water is soft here in Seattle when I first started with planted aquariums I had deficiency issues which I traced to low Ca and Mg. 

I did some research on proper dosing for the two and found that the recommended ppm ratio of Ca:Mg is approximately 4:1. FYI, the ppm ratio in Equilibrium is approximately 3.3:1.


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## happi (Dec 18, 2009)

Seattle_Aquarist said:


> Hi Hoppy,
> 
> Because our water is soft here in Seattle when I first started with planted aquariums I had deficiency issues which I traced to low Ca and Mg.
> 
> I did some research on proper dosing for the two and found that the recommended ppm ratio of Ca:Mg is approximately 4:1. FYI, the ppm ratio in Equilibrium is approximately 3.3:1.


30ppm Ca and 7-10ppm Mg is what i was told when using EI.


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## OverStocked (May 26, 2007)

Hoppy said:


> How did you arrive at 2-5 ppm as the recommended level of Mg in a planted tank? If you have 4X that in calcium, or 8-20 ppm, you only have around 1 degree of GH, which is pretty low. I would expect that the recommended amount of Mg would be in the 50 ppm area. Also, I don't recall seeing that a ratio between calcium and magnesium is significant for aquatic plants.


Target dosing according to Wet's calc is around 5-11 ppm, as best I can tell(for EI). 

http://calc.petalphile.com/

50 ppm is pretty high.


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## plantbrain (Dec 15, 2003)

I do not think any EI article I ever wrote stated a Ca or Mg, but anything over 2ppm up to 30ppm I guess for Mg is fine.and Ca, it can be anywhere from say 3-5ppm up to 100ppm.

Big target.


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## gray_fox (May 9, 2011)

what a discussion i started lol  Well, i changed my water, didnt do quite 70% but darn close....probably ended up at 60% wc. Didnt add anymore Mg. Retested Mg levels and i brought it down to about 50... Should be ok. Ill see how the piranhas are in the morning. My Pelvicachromis Taenatis are doing quite well so hopefully this was part of the cause of the breathing heavily!
Thanks!


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## HD Blazingwolf (May 12, 2011)

i read that you hadn't changed water in a while. you might try doing it more often. it helps keep the water chemistry balanced. also mg is capable of raising your ORP or oxygen reduction potential. doesn't mean it wipes out oxygen but it starts breaking down organics. you may have an ammonia spike if this is the case. 
i'm assuming the spike is possible based on non frequent water changes


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## gray_fox (May 9, 2011)

oh i am well aware of that, but thanks though  I got married in July and my life just went crazy since, and is just now starting to calm down... All myplants and everything died, just didnt have time to keep up with it... Life is finally starting to calm down enough to the point where now i can actually just sit and do testing and other necessities.


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## gray_fox (May 9, 2011)

oh and by the way, fish are looking better this morning, more active and not breathing as rapidly.


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## Seattle_Aquarist (Jun 15, 2008)

Hey gray fox,

Glad to hear the fish are improving. I believe that Piranha are a soft water fish from the Amazon so they probably don't appreciate a lot of Ca/Mg in their water.


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## gray_fox (May 9, 2011)

actually to my surprise, they do quite well in my hard water tank..... i havnt lost one yet, they are about 8 inches in length. I want to get more but cant find anyone near me that sells them.....My LFS carried them but since the new management, they stopped getting them  But ya, hard water and the Piranhas are doing great :-D


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