RH... your input please!

[Phalguy]

Hello everyone!

My name is Claude and I live in Montreal. I grow mostly Phal species in a shelving unit in my kitchen.
I grow in SH culture.
( you can see my installation at: www.picturetrail.com/phalguy )

It`s a wooden shelving unit. Top, bottom and 3 sides are covered with heavy duty plastic.
Each shelf ( 3 ) has 4 40 watts, 48 inches fluorescent tube.

I can maintain an average of 24 to 25 C daytime and 18 nighttime.
Here is my problem.... I can hardly maintain a 32 % humidity. I have tried to cover my entire unit with plastic but it`s not enough. I added 2 fans, blowing through a cotton cheese, soaking in water and the RH went up to 50% max.
I would like to know what is the best way to increase RH in my installation without beeing too costly !

thanks for your input

Claude