Does anyone have any tips on increasing airflow through the scrubber?

I have a 6" 250cfm inline fan hooked up to a cool tube with a 250W HPS in it and my filter at the end. It goes tube -> elbow -> fan -> about 6' of duct -> scrubber at the end.

The temps are too high (> 30 C) with the door closed so I have been leaving it open. Now I'm closing the door but have removed the scrubber. I plan on buying a Vortex fan to fix the problem, unless someone here can help me out.

So has anyone had this problem before? Any ideas?

-canuck :jointsmile:

edit: The scrubber is the same size as this one, 4" and 6" and the roughly same length. This means I have 2x 4-6" reducers at the opening of the scrubber which probably inhibits flow. My fan and duct are 6" and that was the only way to fit it without making a giant filter.