# What happens to the sulphate?



## EnderUK (22 Jul 2014)

Okay to part question, I'm sure one of you intelligent people can tell me. I stick in MgSO4 and CaSO4 into my tank what happens to the left over SO4? Is it part of the pollution and one reason to do water changes? Also if I changed to CaCl what would happen to the chlorine? just gas off I'm guessing.

Thanks in advance.


----------



## dw1305 (22 Jul 2014)

Hi all,


EnderUK said:


> stick in MgSO4 and CaSO4 into my tank what happens to the left over SO4? Is it part of the pollution and one reason to do water changes?


 Pretty much it just stays there until a water change, plants will take up a small proportion of the SO4-- (it is an essential micronutrient) and a small proportion may form fairly insoluble sulphates (only CaSO4 really, and dependent upon all sorts of factors).


EnderUK said:


> Also if I changed to CaCl what would happen to the chlorine? just gas off I'm guessing.


No it will remain as Cl- ions, nearly all chlorides are soluble. The reason the sea is salty with NaCl is that plants don't have much need of either sodium or chlorine, so over time it has built up in the sea (and the sea now contains more Cl- (and SO4-- ions) than it did ~600 million years ago).

That is also why we can get both magnesium sulphate and sea salt as evaporites from sea water. 

cheers Darrel


----------



## EnderUK (22 Jul 2014)

So the only solution is water changes then, I'm dumping quite a lot into the water, so even with water changes it will have a high ppm since there's none taken up by the plants. Does it have any effect on fish at high PPM?


----------



## dw1305 (22 Jul 2014)

Hi all, 





EnderUK said:


> So the only solution is water changes then, I'm dumping quite a lot into the water so even with water changes it will have a high ppm since there's none taken up by the plants. Does it have any even on fish in high PPM?


 I don't think these sorts of anions have much effect on the fish, you can think of it a bit like nitrogen gas (N2) it is 70% of the atmosphere, but it doesn't really have any effect on anything. 

The ions will contribute to the conductivity, but that is about it. 

cheers Darrel


----------

