DIY remineralization problem

[mark0]

Hello, I am trying to solve a weird problem I have with my DIY solution. I used the IFC-fert-calculator to try to duplicate SaltyShrimp but I've ran into a strange problem: my shrimps are going absolutely NUTS after a waterchange (and some shrimplets dissapearing) and I really can't figure out the problem.
How I do my waterchange:
Prepare the solution in a separate container and let it mix (with a powerhead and an airstone) for at least 24 hours. Even though we have low levels of chlorine and the water is filtered through activated carbon I still used de-chlorinator (Tetra Aquasafe) and the result was the same.
What am I doing wrong?
PS: I keep neocaridina and use minerals because my tapwater is extremely soft (40 ppm TDS) - about 2ppm GH and 3-4 ppm KH.
What I mix in the water: CaCl2.2H2O; MgSo4.7H2O; KCO3; CaSO4.2H2O
Symptoms: Shortly after after the waterchange the shrimp become frenetic and swim around like a female just molted. After about 1 hour the shrimp become inactive and sloppy but they quickly recover and are active the next day. I constantly get berried females so the stress is only temporary. Plants in my tanks are doing fantastic. Other fauna like daphnia, seed shrimp, cyclops, blackworms and different types of snails have absolutely no reaction.

What are your opinions on this?
PS: Raw materials are bought from a local Romanian company and are high purity grade. I can provide (and translate) labels and the paperwork the company gave me in which detailed information about the contents can be found.

 

[Hufsa]

I cant see any problem with the numbers you have posted 🤔
I have seen a few user reports of shrimp reacting to potassium carbonate (at least this is what I can recall, so dont quote me on that). But those few reports didnt come to anything conclusive.. Im trying to find if I bookmarked them, but it would appear not.. (Edit: Here and here)
Potassium carbonate would be one potential difference from commercial KH raising salts. The reason is that potassium salts are more expensive, so the companies usually use sodium (natrium) salts.
Its possible that there is something here, but I wouldnt be able to say for sure.
Hopefully our more chemistry knowledgeable people will be able to advise further.

If nothing else, perhaps you could reduce the usage of potassium carbonate for a while, to see if the symptoms lessen?

Also, can you think of anything else that might have changed in the tank or care lately, and write them here for us?

 

[mark0]

Nothing really changed other than switching from Salty shrimp gh/kh+ to my DIY mix and I really think returning to them because my shrimplets population is practically extinct.
I also changed the WC schedule because of this chaotic reaction and instead of changing weekly I do one every two weeks. I avoid introducing new things into my tanks when my colonies get established so I don't buy new shrimp, new plants or really make any change. I do feed different foods but they are always vegetable-based and tested so I know they work.
I'll try to swap the potassium but isn't sodium kind of worse? From what I have read freshwater organisms use little to no sodium.
LE: Thanks for the links. I'll read them thoroughly and also hope for someone more experienced to come by. Many, many thanks!