# MGSO4 vs MGSO4.7H2O



## Immortal1 (Feb 18, 2015)

Sunday morning bitch session, LOL.
Just learned something this morning - MGSO4 and MGSO4.7H2O are NOT the same thing.
MgSO4 versus MgSO4.7H2O - Fertilizing - Aquatic Plant Central

Don't know why but I just assumed they were when I started dosing MGSO4 to my tank after water changes. Seemed odd to me that one weekend I would have to add a little MG to the tank, then the following weekend I would need to add a bit of CA to the tank. Now I know why. If you look at post #8 of the above link it pretty much explains things.

So, now my bitch...
Why do both of my favorite calculators, Zorfox and Rotala Butterfly only list MGSO4.7H2O? 

The fertilizer sites I frequent Dry Fertilizer - Individual Fertilizer - NilocG Aquatics and Aquarium Plant Fertilizer | Green Leaf Aquariums only carry MGSO4.

Didn't realize when I went down the planted tank road that I would need to be come a chemist :nerd: to keep the tank looking good!

Ok, ran't over :grin2:


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## Quagulator (May 4, 2015)

I'm curious to know which CaSO4 option to punch into Rotalabutterfly.... 

CaSO4.1/2H2O

or

CaSO4.2H2O


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## Immortal1 (Feb 18, 2015)

LOL, have not got to that problem yet. But I fear sometime soon I will :angryfire


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## MCFC (Feb 12, 2017)

The MgSO4 from Nilocg is actually MgSO4.7H2O, it says so in the description. Same for CaSO4 from him, actually CaSO4.2H2O


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## burr740 (Feb 19, 2014)

nilocg's is MgSO4.7H2O and I'd be willing to be GLA's is too even though they dont specify. Seriously doubt they're selling a water free lab grade version. It'd be a good question to ask them.

Just grab a 3 lb bag of Epsom salt from wal-mart or the grocery store for 2 bucks. Problem solved.


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## Immortal1 (Feb 18, 2015)

Ok, now my head is starting to hurt.
Pretty sure the 1 pound of MGSO4 is from GLA from about 2+ years ago (don't really use much). Or did I get more from NilocG??? 

Ahhhhhhhhh

:grin2:


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## Greggz (May 19, 2008)

I'm almost positive that GLA is MgSO4.7H2O, based on the structure of the granules.

And I'm not so sure Epsom Salts at the store is necessarily exactly the same.

I looked up something called pure epsom salts at Walmart, and here is the list of ingredients:

Magnesium Sulfate (Epsom Salt), Fragrance (Parfum), Cymbopogon Schoenanthus (Lemongrass) Oil, Mentha Viridis (Spearmint) Leaf Oil, Menthol

Either way it's cheap. Two bucks a pound at GLA.


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## burr740 (Feb 19, 2014)

Mine from walmart is just epsom salt, this bag

https://www.walmart.com/ip/Epsom-Magnesium-Sulfate-U-S-P-Salt-8-lbs/49231899

Obviously it pays to read the label to make sure you arent getting anything fancy


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## Immortal1 (Feb 18, 2015)

Greggz said:


> I'm almost positive that GLA is MgSO4.7H2O, based on the structure of the granules.
> 
> And I'm not so sure Epsom Salts at the store is necessarily exactly the same.
> 
> ...


But I "want" my tank to smell nice LOL. Ok, have to say thank-you guys for the chemistry lesson. Guess I should have realized "if" the major sites only list a specific product that there is probably a reason why (i.e. we don't get lab grade versions for our hobby). In the big picture, it likely would not make any noticeable difference to the plants if I just assumed one or the other. But, stubborn me just wants to get things perfect :grin2: - unfortunately I am not smart enough to realize if it wasn't perfect :wink2:


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## JusticeBeaver (Oct 28, 2017)

Immortal1 said:


> But I "want" my tank to smell nice LOL. Ok, have to say thank-you guys for the chemistry lesson. Guess I should have realized "if" the major sites only list a specific product that there is probably a reason why (i.e. we don't get lab grade versions for our hobby). In the big picture, it likely would not make any noticeable difference to the plants if I just assumed one or the other. But, stubborn me just wants to get things perfect :grin2: - unfortunately I am not smart enough to realize if it wasn't perfect :wink2:


You can make the anhydrous version by putting it in the oven at like 450F. It probably won't be completely anhydrous though since that's pretty low but you'd get close. Also it'd be incredibly hygroscopic so you'd need to store it in a very dry and airtight container. It's much easier just to use the hydrated stuff.


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## Jeff5614 (Dec 29, 2005)

Immortal1 said:


> But I "want" my tank to smell nice LOL. Ok, have to say thank-you guys for the chemistry lesson. Guess I should have realized "if" the major sites only list a specific product that there is probably a reason why (i.e. we don't get lab grade versions for our hobby). In the big picture, it likely would not make any noticeable difference to the plants if I just assumed one or the other. But, stubborn me just wants to get things perfect :grin2: - unfortunately I am not smart enough to realize if it wasn't perfect :wink2:


I like a good smelling tank also. Just a bit of useless info here. ADA sells, or did sell, scented CO2 canisters. They had two or three different ones to give you that forest fresh smell. They also sell a device called Air Sweeper that you connect to your air stone and pump for night time aeration that contains beads that absorb odors.

You're all welcome, lol.


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## Seattle_Aquarist (Jun 15, 2008)

Immortal1 said:


> Sunday morning bitch session, LOL.
> Just learned something this morning - MGSO4 and MGSO4.7H2O are NOT the same thing.
> MgSO4 versus MgSO4.7H2O - Fertilizing - Aquatic Plant Central
> 
> ...


Hi Immortal1,

Yes, there is a difference between MgSO4 and MgSO4*7H20 although some sites use the terms interchangeably. MgSO4 is stronger that MgSO4*7H2O but more expensive as well; I've used both and MgSO4*7H20 (aka Epsom Salt) is much more economical (and available). Calcium Sulfate we typically find in the hobby is CaSO4*2H2O which is 100% pure gypsum (if you can find it without additives).


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## Maryland Guppy (Dec 6, 2014)

Immortal1 said:


> But I "want" my tank to smell nice LOL.


I will not tolerate any smell. LOL :grin2:
Don't want to know there is an aquarium nearby from sense of smell.
Only permissible items are plants pulled for a trim.
It is very strange the smells emitted from some of the plants we keep.

There is a rough time in the Spring.
Heating is off and not ready to turn on the A/C quite yet.
It is a humidity thing, not really a smell per say.


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## Raith (Jun 27, 2014)

Just to piggy back a bit, I have two bags of Epsom Salt, about $5 or so, and it's more than what I'll ever need. Dosing however... for a 55G tank, how many grams would that be in this form? I'm trying to find information on this. D: Also... from what I read, Magnesium hardens the water? I'm trying to add some macro nutrients to my plants to thrive, and my water is already hard, so in EI dosing, it should be fine right if I make it so Saturday becomes my water changing day?


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## Grobbins48 (Oct 16, 2017)

Just wanted to throw out a thanks for this thread, as I was having some of these Mg questions myself. I'll add epsom salt to my list next time I am out, starting to run low of my bag from GLA.

Oh, and I'll probably skip on the fragrance 

Sent from my SM-G950U1 using Tapatalk


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