The invention relates to a method for casting a melt (15) and to a casting tube (3) for a continuous casting system. The aim of the invention is to provide a method and casting tube (3) by means of which a cast product having a homogeneous, fine microstructure having a low proportion of segregation can be obtained. Said aim is achieved by a method comprising the following method steps: feeding the melt (15) from a casting distributor (1) into a chill mold (5), wherein the melt (15) is fed at least partially in the interior of at least one casting tube (3), and wherein the melt (15) is cooled in at least one casting tube (3), such that the melt (15) comprises a solid proportion of 10 to 60 wt % when exiting the casting tube (3); cooling the melt (15) in the chill mold (5), wherein an at least semi-solidified cast product is formed; and drawing the cast product out of the chill mold (5), wherein the cast product is supported, guided, and optionally further cooled by a strand support device downstream of the chill mold (5); wherein the cooling of the melt (15) takes place by means of at least one heat tube (8) or at least one thermosiphon.