Efficiency or functional ability of homemade pvc carbon filter

[lx574]

My first post here. I am from a third world country.The cannabis we get here is very low quality and it's also very risky to buy. So this is my first attempt to grow my own. I tried my best but couldn't buy a quality grow tent and it was almost impossible to source a carbon filter. So I have made a wooden grow cabinet myself and made the re-usable carbon filter using pvc pipes based on the information available in internet, thanks to the global cannabis community. The problem I have is, I am really concerned if my carbon filter would work. I don't want to wait till the flowering stage to test if it really works in eliminating the order.
I am growing two plants ( bubba kush auto and blue kush auto) and currently on the seedling stage. I tested it with incense stick but I could smell it outside the grow box, but later understood that its not the right method. It would really help to know if there is any other valid method that I could employ to test my carbon filter. I have attached the pics of my set up. I just hope my filter works. Filter is about 1 foot long and 6 inches in outer diamter.

 

[desertdan]

Put a bag of fresh dog poo in the box and see if it smells outside.

 

[smoorman]

Even the standard sized 8-10" dia filters do not totally scrub the smell clean. That of course depends on how many plants-size Etc. I am not sure but it looks like you need about triple the number of holes in the filter depending on the fan that is attached. Sum up the total area of all the small holes on the inside tube of your filter and then see how big a diameter that is. Your fan will overwork if if there is not a free flow. Are you able to vent the filter outside and up? Have you setup your lights and confirmed the temperature inside the cabinet? So many things to consider but you came to the right place.

 

[lx574]

I am growing two plants only. I am ok to go with even 1, the other is actually for redundancy should something go wrong . I have tested the temperature and it doesn't cross 29C (84F) with full led power (200watts actual) running for few hours. I had initially hung the led inside the cabinet but the temp was reaching 34C(93F) within 1 hour since the led was exhausting within the cabinet. I cut the upperside of cabinet so the led heatsink mechanism is sitting outside and doesn't vent inside the cabinet. luckily it was a perfect fit without air gaps. Led doesn't use the air from inside. Since the entire heatsink is sitting outside cabinet, it uses external air for heat dessipation. As to the carbon filter, when the filter is attached to the exhaust, fan output force is reduced by almost 50%. Since I had tightly packed the activate charcoal, I was under the assumption the resistance was due to that but what you said makes sense. I roughly added up the surface area of inner holes and it comes upto about 400 mmsq (200 holes of 2mm each) which roughly translates to about 3inch diameter wherein the inner pipe/fan diamter is 4inch. So looks like I definitely need an increase of 25% to 50% of inner holes,perhaps even 100%. I can then confirm if the reduced fan force is due resistance from charcoal/air flow or just less number of holes.
Also it doesn't really matter to me if the fan fails in 6 month due to overworking. It's cheap here since it's locally made. Drilling the holes is a real pain if I have to be honest and I'd rather shell out 10 dollars every 6 months than drill another 100 holes on those PVCs. Do you think I can get away leaving it as it is?
One potential problem I see is the positive air pressure within the cabinet due to reduced exhaust and increased inlet air. This might result in air escaping through tiny vents unfiltered. I am planning to counter this by somehow reducing the inlet air and maintain neutral or negative pressure.

 

[smoorman]

It sounds like you're thinking this through pretty well. That was a pretty slick move mounting the LED outside. I think you need to re-calculate the total area of the hole. There are 645 sq mm to 1 sq inch.
Diameter squared times 1/4 pi (.7854) =area of circle. 4*.7854=3.14sqmm. You've actually got less than a square inch of area total. Please correct me if I'm wrong.

 

[lx574]

Thank you sir. You are right. I did the recalculation and look like I need to triple the number of holes.
1. Surface area of each hole = 3.14sqmm.
2. There are about 230 holes, so 3.14X230=722sqmm ( total hole surface area)
3. Diameter of total holes would be = 3.03 cms which is just about an inch. I think earlier I got confused between cms and inch.
I would need a minimum another 400 to 500 holes in each pipe. I'll probably increase the size of the existing holes with bigger nails and add extra holes. Thank you, much appreciated. I will need to do this later this week. Currently both my seedling growth are stunted. They are in Day 10 now and haven't grown much since day 4. I will need to do some reading and will probably post another thread if I can't figure out.