[quote=@Blizz]
[@MonsieurShade]I'd have to assume that electrocution could be a hazard for jack in his ink form, though I don't exactly see how Ptolemy is a high risk person(or fish person) to fight
[/quote]

Water is known as the universal solvent. Enough of it would very easily disperse and dilute ink to a point where it would be near impossible to use properly. Due to Ptolemy's hydrokinetic abilities he could, in time, render the usage of ink by Jack null if Jack were to provide some sort of opening.