choosing a diffuser for small tank

[markp35]

i was going to do a big planted tank , but have decided to be sensible and use my empty 112L to learn on 1st. it will be filtered by an internal filter with a powerhead providing the rest of the turnover. this means il be using a glass diffuser in the tank instead of the inline atomiser originally planned . are there any considerations when choosing the right 1. obviously they all claim to be fantastic etc but what seperates a good 1 from a not so good 1?

im thinking about this 1 . any good?

http://www.aquaessentials.co.uk/ae-desi ... -5430.html

or theres this in tank atomiser by UP .

http://www.aquaessentials.co.uk/up-co2- ... -2161.html