Plus the size of your tank, what type of shrimp you are keeping , and the size of the coral .
For smaller tanks within the 1 to 5 gallon range you hardly need any coral unless you have a massive calcium deficit.
In my opinion that coral chunk is far too big for a 15 gallon tank , and could cause the water to be too hard. This would cause failed moults from their shells being too hard.
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Depends entirely upon your ph , gh , and kh.
Plus the size of your tank, what type of shrimp you are keeping , and the size of the coral .
For smaller tanks within the 1 to 5 gallon range you hardly need any coral unless you have a massive calcium deficit.
In my opinion that coral chunk is far too big for a 15 gallon tank , and could cause the water to be too hard. This would cause failed moults from their shells being too hard.