Halakhah do Mikwaot 7:8

And the law of carving out a vessel before he fixed it [in the ground], or if he fixed it and afterwards carved it out; and how much carving out is [needed] to disqualify - and the difference between an earthenware vessel and other vessels, as an earthenware vessel is not disqualified until it be carved out enough to hold a reviit, whereas a wooden vessel [is disqualified] with the smallest amount. And that which they said (Shabbat 14a) that a mikveh is not disqualified with a change of smell or a change of taste, but rather only with a change of appearance. And any [liquid] from which we do not make a mikveh from the outset - such as wine, milk, blood and also the juice of any fruit - disqualifies the mikveh with a change in appearance. But if some of it fell into [the mikveh] and it did not change its appearance, it is not disqualified. As it is only with drawn water that they decreed and said that three log disqualifies. But fruit juice does not [disqualify] until the appearance of the water changes from their mixing [in] (see Mishnah Mikvaot 7:5).