The pressure should be low as low pressure can melt the crystals easier way
According to Gay lussac's law pressure is directly proportional to temperature so temperature should be also low as it's general any thing need to be cooled down inorder to get crystallised
Now for amount of dissolved solids the solution should be super saturated like magma .It denotes that the particles present as solute must be greater than the solubility.
Cooling time also should be long inorder to give time to crystallization
