a lot of Water flow sensors

Hi all,

I’m a beginner with Arduino but i want to use it for a project at work.
I like to measure water flow with an arduino but i want to measure about 90 different flows.
So i will be measuring 90 different flows on the most simple way.
I’ve read about a piece of code that can activate internal pull up resistors of the arduino, i hope this would make it possible not to use separate resistor and make connecting them to the arduino more easy. My questions are:

  • is this right? about the pull-ups?
  • i’m thinking of using a arduino mega or multiple but how much???
  • also thinking of a shield to make connecting more easy, are there any???

Hope someone can help me,

greetz Bert (from Holland)