fan controller question

[FitoPharmer]

I have a 6" ~600 CFM 115w inline fan I am using to vent my new fish room. I was wondering if I can use one of these to control the speed of my fan:
Dimmer switch (http://www.homedepot.ca/product/decora-sureslide-dimmer-with-preset-switch-for-single-pole-3-way-applicatio/813929)
Or will I have to use something like this:
Speedster fan controller (http://www.amazon.com/SE-Electronic-Stepless-Speed-Controller/dp/B000HQAVNI)

I would like to use the switch because it will look cleaner, I have an extra slot left in a 2 gang box I would like to fill, and it is slightly cheaper. I have no idea about electronic though, I was told by others it was a bad idea since AC motors do not like variable current. If that is the case then I would imagine the speedster fan controller would not work either.

[sphelps]

You can only change the speed of the fan if it the fan itself uses a multi-speed motor which is not likely for the type of fan you have. If it did it would either come with a speed controller or reference an optional one. The fan speed controllers you buy are designed to replace existing speed controllers for multi-speed motors. They are not for any old AC motor.

What you should use for control isn't a dimmer anyway but a humidistat that will turn the fan on or off based on the humidity level in the room. You can get ones that fit in standard gang boxes (http://www.canadiantire.ca/AST/browse/3/HouseHome/RangeHoodsExhaustFans/BathroomExhaustFans/PRD~0528200P/Dew+Stop+Humidity+Sensing+Control.jsp?locale=en).

[FitoPharmer]

I already have a dehumidistat wired up to control a socket for the fan. Now I just wanted a speed controller to help make the fan quieter. These fans are sold either with or without control kits, the speedster version. When I was looking up my problem on the internet one site suggested that the speedster unit may change the frequency of the voltage going into the fan to control the speed.