Adam Clarke on 2 Chronicles 4:5

It - held three thousand baths - In 1Kgs 7:26, it is said to hold only two thousand baths. As this book was written after the Babylonish captivity, it is very possible that reference is here made to the Babylonish bath which might have been less than the Jewish. We have already seen that the cubit of Moses, or of the ancient Hebrews, was longer than the Babylonish by one palm; see on 2Chr 3:3 (note). It might be the same with the measures of capacity; so that two thousand of the ancient Jewish baths might have been equal to three thousand of those used after the captivity. The Targum cuts the knot by saying, "It received three thousand baths of dry measure, and held two thousand of liquid measure.