# How high SO4 ?



## kekon (Aug 1, 2005)

I found T.Barr article in the internet where he wrote:

Plant inhibition:

Ca over 400 ppm
Mg over 50 ppm
SO4 over 50 ppm
PO4 over 6 ppm (?)
Fe over 2 ppm (?)
K over 50 ppm (?)
NO3 over 75 ppm

(?) - i don't remember an exact value

I wonder what SO4 levels really stop plant growth. Some say they didn't notice any issues even at 200 ppm of SO4 in their tanks. Others say, sulphur excess can induce Ca deficency. I'm confused. Have you noticed any negative effect of elevated SO4 levels ? (once i wanted to use only CaSO4 as a source of Ca to reconstitute pure RO water; Edward said plants don't like CaCO3 - but i didn't notice that)


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## Edward (May 25, 2004)

kekon said:


> I found T.Barr article in the internet where he wrote:
> 
> Plant inhibition:
> 
> ...


Most fish and plants wouldn't be happy in the above mentioned levels. 
In regards to the SO4 toxicity I wouldn't worry. There are no known issues. We dose tons of SO4 from K2SO4, MgSO4 and CaSO4. S is an essential plant nutrient and is mobile. Plants will take it in excess if available. 

CaSO4 is an excellent source of Ca, it does work well. However, it can not be used with dosing pumps as it doesn't dissolve easily. It needs to be dosed dry. The best levels are 20 - 30 ppm Ca. 


CaSO4 0.3622 grams per 100 liters => 1 ppm Ca

grams.per.100.litre.per.1.ppm


Thank you
Edward


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## kekon (Aug 1, 2005)

Thanks for reply Edward. In the past i didn't notice any negative effect of SO4 (i had 74 ppm SO4) but i wanted to be sure about it. However, i had some issues when using CaCl2. Cl above 10 ppm from CaCl2 caused some leaves to wilt.


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## Salt (Apr 5, 2005)

The Ca and Mg values are meaningless unless it's known if they are in a CaCO3 equivalent or not. I'm pretty sure they are, but it's important to specify.


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## banderbe (Nov 17, 2005)

I think it is easy to make this hobby more complicated than it needs to be.


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## kekon (Aug 1, 2005)

banderbe said:


> I think it is easy to make this hobby more complicated than it needs to be.


Come on... I agree that we sometimes go into details too much, but it's also very interesting. My tank is getting better and better, plants grow healthier - just because i learnt many details about the hobby. You know, in my country we don't have access to such products like Flourish, Barr's GH Boosters, TMG etc. (however, TMG is accessible only via internet shops but it's very expensive and only few people can afford buying it). That's why we like (or we have to...) deal with details (making our own ferts, mixtures, salts etc.)


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## detlef (Dec 24, 2004)

Kekon,

where in the internet did you find such data from Tom B.?????

Regards,
Detlef


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## kekon (Aug 1, 2005)

Unfortunately i have the article on the hard disk at work and now i'm on holiday... Anyway i will get it on Monday and it will be available here.


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## fish_4_all (Jun 3, 2006)

http://www.barrreport.com/


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## Zapins (Jul 28, 2004)

Wow thank you kekon, I have been wondering/searching for inhibition levels like you just posted right now for quite some time. 

I suspected that the NO3 inhibition/K inhibition level were pretty close to what you mentioned above, but it is VERY helpful to know the other parameters.


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## detlef (Dec 24, 2004)

Hi kekon,

still waiting for the source T.Barr wrote about inhibiting levels ...

Can't remember seeing those on barrreport.com


Thank you,
Detlef


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## kekon (Aug 1, 2005)

Sorry for the delay. The article i've told about is here:

http://www.plantedtank.net/forums/154535-post24.html


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## detlef (Dec 24, 2004)

Found it,

thanks again, have a good day!

Best regards,
Detlef


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