Ventilation question

Hello folks,
I am starting a 48X24X60 grow tent and I just had a few questions about ventilation.
1. My plan is to use a ValuLine 6 in Centrifugal Fan - 435 Cfm for fresh air intake at the bottom of my tent and then an Active Air Blower System - 60 CFM at the top of my tent for exaust. Would this work? It sounds like it could be too much intake and not enough exhaust?
2. My second question is about fan timers. Is it ok to just run these fans non-stop or do I need to invest in timers? If so does anyone know of any economical timers?
Thanks for the help and stay medicated :smokin:

BTW I forgot to mention I am using a sun system 2 400 watt light. MH for veg and HPS for flowering

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Originally Posted by chron legacy

BTW I forgot to mention I am using a sun system 2 400 watt light. MH for veg and HPS for flowering

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You should put the exhaust fan on a thermostat.. Two 400 watters are gonna get very hot. Are your hoods enclosed? The 435 should be used with exhaust and the smaller fan really ain't needed. The exhaust will create a passive flow into the tent while the exhaust is on..

Sorry for the confusion. It is a single 400 Watt light and the brand name or sytem name is sun system 2.

http://www.thehydrosource.com/Lighting/Reflectors/Sun_System_2_400w_Switchable_MHHPS with an MH for veg and HPS for flowering.

Also thanks for the fan advice. Any money that I am able to save is great so I really appreciate it!

Spacey right now haha. But yes the hood is enclosed

Even if the hood is enclosed,you'll need good ventilation. I see a use for the smaller fan now. You should have flex from outside the tent,running to one end of your light and the other end to the fan exiting the tent.Hang the smaller active air fan inside the tent and open a flap on the bottom of the tent for a passive flow. Exhaust the small fan outside the tent as well... You'll have your ventilation working like it should without collapsing your tent,or sucking the sides in..

Thanks man your answers have been way helpful. :stoned:

Cool! Glad to have been some help ta ya!