Something like the Airoflow is better for a tent from the research I have done. The cool tubes are nice but a coolable hood like the Airoflow can be cooled just as well but have a bigger footprint. I just got an Airoflow and a 600w Digi HPS and it is great. I can add another 600 with no problem when I move and cool them both with the same fan I bought.
If you have a 4x4 tent you will want a 600w. A 400w is okay for a smaller tent