<Tr> <Th> 43 </Th> <Td> 17 </Td> <Td> "The Merman Code" </Td> <Td> Grant Brown </Td> <Td> Sam Carroll </Td> <Td> 7 June 2015 (2015 - 06 - 07) </Td> <Td> 29 May 2015 </Td> </Tr> <Tr> <Td_colspan="7"> Ondina and Erik are spending increasingly more time together causing Mimmi to feel neglected . Meanwhile, Cam studies a photo of the stone pedestal from the merman chamber and discovers that the stone carving matches a satellite photo of Mako Island . He also suspects that the symbols on the carving correspond to the outcrops on the reef surrounding the island . He shares his thoughts with Erik and the two decide to investigate the outcrops on the reef . The two find a symbol of a trident on the outcrop but when Erik touches it, he is teleported into a realm of endless water with no way out . Cam rushes back to land and asks Zac and the three mermaids for their help to rescue Erik . While out on the island, Ondina and Mimmi get into a heated argument about their different opinions of Erik causing a rift between them . The group soon realize that they must risk activating the chamber to rescue Erik . Mimmi is able to figure out the order of the pedestal's code and Erik is set free when Zac activates the chamber . Afterwards, Ondina and Mimmi reconcile with Ondina promising never to let Erik come between their friendship . </Td> </Tr> <Tr> <Th> 44 </Th> <Td> 18 </Td> <Td> "The Siren" </Td> <Td> Grant Brown </Td> <Td> Sam Carroll </Td> <Td> 14 June 2015 (2015 - 06 - 14) </Td> <Td> 29 May 2015 </Td> </Tr> <Tr> <Td_colspan="7"> Sirena sees a video of a mermaid enchanting a kayaker with an enchantment song and it has unexpected consequences . Sirena falls under an enchantment that causes her to care for nothing more than being with David and she begins following him obsessively . Mimmi manages to obtain the video and watches it . She realizes Sirena is under the spell of a northern mermaid siren song that affects men and southern mermaids . Mimmi, being a northern mermaid, is immune to the effects of the song . That night, Sirena enchants David with the song and takes him to the Moon Pool to make him her man . Fortunately, Ondina and Mimmi are able to break the spell by singing a counter enchantment song . Sirena comes back to her senses and Ondina uses her moon ring to send David back to his boat with no memory of what happened to him that night . </Td> </Tr>

When does zack find out about the other mermaids