the ratios were varied at/by three levels

[Nucleara]

Hi,

This is part of a project abstract. I want to say that there are three treatments (levels of the the ratios) but I am unsure about the prepositions here:

1. The ratios of brown rice flour and rice flour were varied at three levels: 60:40 70:30 and 80:20.
2. The ratios of brown rice flour and rice flour were varied by three levels at 60:40 70:30 and 80:20.

Which one looks better?

I didn't want to put another at in 1. because it looks repetitive, so I used a colon instead.

Thank you.

 

[Myridon]

Nothing is varying (changing) - three are simply three things.
There were three ratios of brown to white rice flour: 60:40, 70:30, and 80:20.

 

[Nucleara]

Nothing is varying (changing) - three are simply three things.
There were three ratios of brown to white rice flour: 60:40, 70:30, and 80:20.

Thank you Myridon.
I mean I vary the ratios to 60:40, 70:30,... Doesn't it make sense to the sentence?