In these case, angels live amongst us.
, just to add info, I got an extra tool for us
I sent a picture showing how much Mg should be added in 600 liters in drydosing using Rotalla and placed it in Dosierberchnung calculation. I increase Mg by 20mg/l (which is correct) but I am just concern about the sulfate that has been added into my tank (78.99mg/l). Is this is safe in Discus aquarium?
In picture 2, it shows how it increases the Hardness of water (+4.6º dGh)
I can’t comment on that website as it is in German (which, I can’t read).
Water hardness (as defined in NA) is based upon magnesium and calcium and measured by GH. I believe that, in Europe, and perhaps elsewhere, the term “hardness” also involves alkalinity, as measured by KH. So, on this forum, when we speak of “hardness”, we are referring to GH. Just want to clarify that before going further.
Based upon your image, you are adding too much Mg at 20 mg/l for my tastes. We generally recommend Mg levels in tandem with Ca and like to see a Ca:Mg ratio of 4:1 or 3:1 (I prefer 3:1). So, if you add 20 mg/l Mg and target a 3:1 Ca:Mg level, you would need to add 60 mg/l Ca. Using RotalaButterfly, if you then add the dGH shown for each (4.62 dGH of Mg and 11.21 dGH of Ca), you will have a total dGH of 15.83 and that would be considered to be very hard water. I believe that most of us would prefer half of that. I target about 3 dGH in my tank, which is considered soft water. Whatever you do add, make sure that it is designed as a function of what you want your tank water readings to end up being.
There are other interactions between nutrients and high levels of Ca and Mg can be involved. For example, we also like to see K be higher than Ca, in addition to Ca being higher than Mg. I suggest that you would gain a better understanding for balancing all of your nutrients by studying both the PPS and EI approaches to nutrients, then choosing one of these approaches to follow. You can find this information by searching this forum.
Addressing your concern about sulfate, it is usually quite a bit higher than Mg because it is also added by other salts.