Comparing the CAN 2600 to the GrowBright Pure Flow Jr. Can Filter 2600 Specifications: Max Recirculating (Scrubbing) CFM: 90 cfm / 142 m³h Max Exhaust CFM: 42 cfm / 71 m³h @ 0.1 sec contact time Prefilter: Yes Mounting: Bayonet or Regular Flange: 4" Dimensions: (with pre-filter) ·Outside Diameter: 14cm / 5.5" ·Height: 45.3cm / 18"·Total Weight: 4.5kg / 9lbs.·Carbon Weight: 2.1kg / 4.63lbs Pressure drop at max cfm: 42pa / .20"wg Recommended Fans: FAN Watts Consumed Filtered Air CFM Can-Fan 4" 62 Watts 88 CFM 6" Axial (Com GrowBright: Recommended Max Airflow: 150-265cfm / Carbon Weight 4lbs WHY does the GrowBright Pure Flow Jr. have a HIGHER recommended CFM when it in fact has LESS carbon than the CAN 2600 (4lbs vs. 4.65lbs)? Is it because the GrowBright has a higher static pressure than the CAN and as a result requires more CFM to pull the SAME amount of air through? I think this is the case for a couple reasons: I have the GrowBright Jr. and when you take the pre-filter off you can see that air flows through small holes that have been punctured into the metal (I took a picture: http://i55.tinypic.com/2i27j43.png). If you look at the picture of the CAN 2600, it looks like there is a mesh that allows far more air through. Second, if you roughly calculate the surface area of area that the air will flow through, the CAN 2600 is 20% larger (because it is 6" longer, albeit narrower by 1"). Both these filters are about the same price, but the CAN 2600 requires a much lower CFM to clean the SAME amount of air through! So if you have a 200 CFM rating fan with the GrowBright filter, and a 50 CFM rating fan with the CAN 2600 filter, you are actually venting the SAME amount of air even though you might think you have more ventilation with a 250 CFM fan! Plus, the 50 CFM will be MUCH quieter. I think that given this information, the GrowBright Filter is complete junk and is not worth buying. I think this goes the same for other carbon filters that are built similarly. Someone please check my logic. I am open to any ideas. I got the specs from: Can-Filter Specifications (CAN 2600) High Tech Garden Supply (GrowBright)
In the approximate, immortal words of rumpleforeskin.... "overkill is best with ventilation". I saw him say that somewhere, and that dude is a full blown pro. I think you're reading way too much into this stuff. You wanna cycle the air in the room 3-5 times a minute. You need negative pressure for the filter to do it's job fully. The 6inch fan from HTG is gonna be a bit louder, and you may end up getting a speed control to slow it down. Do the 4 inch fan and filter. Use a seperate fan to cool your light, and run ductwork so it pulls air from outside, through the light and back out, (so no stinky air gets blown out that hole). The difference between those two filters is negligible I think. Maybe one is packed tighter than the other so it needs a bigger fan. I can say from personal experience that I've grown some stinking ass weed, and the the growbright performed above and beyond. My apartment is only 600 square feet, and you could only smell it if you stuck your head into the tent. I'd move more air rather than less. That helps the plants to have more fresh air coming in the intake side.
I am not saying overkill is not bad. I'm saying that even if you think you're going overkill with a 250 CFM fan for a 20 cubic feet grow tent, you're really not. If the carbon is packed more tightly, then that would just increase the static pressure requiring more suction to pull the same amount of air. However, I think you may have a point. The stronger the fan, the less that static pressure affects the CFM of the fan (http://www.hvacquick.com/images/content/sp_td_perf.jpg)
i have a four inch inline fan and hate it.. wish i had gotten the six inch and really slowed it down... only would have cost me 20 more bucks... it sounds like a plane is landing in my cab.... but to others that come over they don't even hear it.... but maybe paranoia has kicked in
hahahaha.. your comparing filters..... make your own.. don't waste money on buying one.. unless you don't have time or your not handy at all..... seriously.. waste