The producers realized after the success of the first season the show needs to grow more as the fans are too,so season 2 was full of action with Charlotte stealing people and powers to her side ,
my thoughts about season 3 it was the most grown season , Bella came with her story of being a mermaid since she was 9 , the season was all about understanding the mysteries of Mako , as Bella is the new mermaid , logically we should know more about her so that's why the first episodes were about her , that brings me back to people who think that season 3 was just about Bella , that's wrong!
Bella's singing isn't for fame , like other people think , she was just practicing a hobby , the goal of season 3 was to show that fans are growing along with their favorite mermaids , and that goal in my opinion is the most important and mature thing!

h2o can mature with every season as the characters mature so can the storylines. My opinion of Bella is that if Emma hadn't of left she still would have been introduced as we learn that there are other places that you can turn into a mermaid as it helps if there's a character that has been transformed somewhere other than Mako.

johnathan shiff said in an interview that he's competing with shows like hanna montanna.
and suprise bella can sing.
kindergartners are more mature than hanna montanna.
shiff is turning h2o into a kiddie pool.

da boss?
oh come on.

one last idea. shiff if you are reading this, it's obvious that claire holt leaving gave you cause to dumb down the show and cheapen it making it buubble gum for the younger viewers. or in this case salt water taffy. minds might explode but bring back holt!
she wasn't my favorite but she's obviously the most mature.

Ok ,First Claire signed a movie before season 3 , there was going to be just 2 seasons but cause of people demands they made season 3! so Claire for sure was going to film season 3 if she hasn't signed any work!
Second Johnathan Shiff didn't make any show about singing if he was going to compete against those type of shows why the bother , he could've made a new show just about singing , not a spin-off of H2o ! So season 3 wasn't about any other shows it was just H2o!