My problem is witch one of arduino should i choose ?? Uno is probaly to small, i dont know how to connect it together because when Touch Screen shield is pluged in it take all of pins UNO.
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Are you sure you absolutely need a touch screen? It would be much easy if you make a webapplication... then you can control and administer your aquarium from everywhere you go... even a smartphone app is a possibility 8)
I'm allso planning an automated aquarium with the use of one or multiple arduino's... If you can google "arduarium practical maker" It's a complete system, always under construction off course...
I can follow your frustrations about using so many pins for just one component. I'm in the very early phases of making my own aquarium controller, and currently learning to program the Arduino and learning how the different components operate.
About the screen, I was recommended a screen from 4D Systems, and went for the µLCD 3.2PT (SGC). It only requires 2 pins (1 for TX, 1 for RX) + of course VCC and GND) and together with avenue33's libraries it's quite easy to program.
The screen is a bit more expensive than the one you link to (79$ + shipping) but it seems to be up for the task. It's quite fast, has built in SD card reader and even a little speaker.
Good luck with your project, and let us know how it goes