How much calcium needs to be in freshwater for nerite snail?

[JoeQ]

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Understanding TDS lead to a huge step in my planted tank game. My weekly 'range' is constantly abouts 135 ~ 165 through the week. If its out of wack that tells me something is up, either with dead organics that need to be cleaned, filter needs cleaning, or a nutritional imbalance that is causing the inability of my plants to take up nutrients.