Diy Carbon Filter

[distracted 27,593]

I needed to vent a small attic grow using an in line fan duct but i couldn't afford much of a filter. Raz's biscuit tin version is really good but the fan I had seemed a bit big for it so I made this:

To make you need:

welded wire mesh (Rabbit hutch stuff)

7" shallow round baking tray/ metal pie tin

2 x 6" plastic flower pots

self adhesive plaster board scrim tape (like sticky net curtain)

Silicon sealant or glue ( I used "liquid metal" as I had a tube already)

sharp wire cutters/ pliers

2 kg of activated carbon

cooker hood filter

First roll a strip of mesh 18" x 25" into a 6" diam. 18” long tube. If you trim the mesh so that it’s got wires sticking out (frayed looking) these can used to fix everything to itself, otherwise just tie it off with loose wire. Once you have the tube the whole thing can be wrapped in scrim tape, overlapping the tape quite a bit as you go.

Now do the same with a 14” x 40+” piece of mesh to make a 7” diameter tube covered in scrim tape.

Now glue the baking tray into the end of the 7” tube.

Push a 6” plant pot into the end of the 6” tube as far as it will go and trim the pot down so that only half an inch sticks into the tube, glue it in place. Put a ring of glue on the plant pot free end of the 6” tube and put it inside the 7” tube (so it sticks centrally to the pie tin). You should now have two tubes one inside the other with a ½ inch gap all round. Fill this gap with carbon, tapping and shaking the carbon down as you go (don’t push it in, just shake it in.) Once it’s full and you are sure no more shaking, vibrating etc will help its time to seal it up. I used a 7” plastic tub lid with a 6” inch hole cut in it (use a plant pot to mark out the 6” circle) which I stuck on and sealed with glue.

Optionally the whole thing can be wrapped in cooker hood carbon sheet to finish it off. Once completed the protruding stub of the 6” tube is wrapped in tape and the fan duct connected to the plant pot.

I run a 680 m3/h duct fan blowing in and as it is outside the grow-room the black filter is not a problem, however if you wanted the filter inside the room a white filter cover would reduce light absorption. I have no odours and it doesn’t seem to affect the fans performance. I originally ran mine inside the grow room but temp issues forced me to extract from an inch from the back of the lamp using flexible 6” pipe. The barn style reflector has a sheet of horticultural plastic sheeting (clear polytunnel plastic) stretched across it so the air is forced to travel over the bulb (600w HPS). So its extraction from reflector > through axial fan > into filter (which just sits upright on the attic floor)

Hope this helps someone or inspires a better version

[Guest Blabblabberbab]

Nice - top stuff mate

B

[adddw 2]

indeed top show...think i may have a go at this

[distracted 27,593]

Cheers for the comments B)

Just to finish off here are a couple of extra photos

This is the filter in action, been on continous for 11 or so weeks and not a whiff

This is the "cooler tube" super cheap style Its polytunnel grade horticultural plastic and it works well even though you would have thought the 600 watter would have fried it

There may be a loss of lumens but for me it wasn't a big consideration. The plastic is held in place with double sided tape and the spring in the reflector keeps it nice n tight. It has to be really well stuck on though otherwise it will get sucked up onto the lamp and melt

[deanbo 10]

That's really good work.

My DIY CF isn't all that good anymore so i was going to save up but i think i might just copy this now.
I caught a little whiff outside earlier,and i'm getting a bit para about it now.

I think i understand how you made it OK,but what is scrim tape ? and more importantly where can i get it ?

I've got plenty of activated carbon,and the mesh and plant pot,and this fitted to a 6 inch dia ?


RVK 150 size ?

That the exhaust fan i've got,but no idea what scrim tape is ?

Edited January 30, 2015 by distracted

[cf 1,076]

scrim is the tape that plasterers use across the joints in the p/boards under the finish coat to stop cracking

any builders merchants will stock it and its very cheap too

[distracted 27,593]

I think i understand how you made it OK, but what is scrim tape ? and more importantly where can i get it ?

I've got plenty of activated carbon,and the mesh and plant pot,and this fitted to a 6 inch dia ?

RVK 150 size ?

That the exhaust fan i've got,but no idea what scrim tape is ?

As CF says the scrim tape is easy to get and cheap. Mine came from B&Q coz I'm lazy. It looks like your grans net curtains in a 2 inch thick roll and it is sticky on one side to help it stick to the plasterboard. You wrap it around the mesh like selotape but its perforated so the air passes through but the carbon stays put

Mine was made for a 6" ostberg fan but the central bit of the filter that you connect to should be basically the same size as your fan. The 7" pie tin sets the gap all the way round so that the air passes through 1/2 an inch of carbon. I blow into the filter using a 680 m3/h fan on full power and its still going great, ran it on suck for a while as well without probs. B)

[Gom Jibbar 2,096]

Fantastic bit of DIY. The only bit I can't quite follow is what the green bit is all about. If that seals the carbon in, how come there is mesh above it? I would have thought the green think would 'cap' the top of it.

[distracted 27,593]

The only bit I can't quite follow is what the green bit is all about. If that seals the carbon in, how come there is mesh above it? I would have thought the green think would 'cap' the top of it.

Sorry it wasn't clear..... it was meant to be covered by this bit "I used a 7” plastic tub lid with a 6” inch hole cut in it (use a plant pot to mark out the 6” circle) which I stuck on and sealed with glue"

here in a better way may be:-

There is a long mesh tube and a short mesh tube both stuck to the pie tin. The gap between the tubes is filled with carbon. A ~7" plastic lid (mine was a tile grout lid) with a 6" hole in the middle is slid over the thinner tube till it hits the top of the shorter wider tube. This is glued into place. The "green" lid now has the 6" tube sticking out of it (with a flower pot in the end) the mesh protruding is then sealed with tape and its done.

[Gom Jibbar 2,096]

Aaah.. I see. Nice one. I had read that the mesh cylinders were different lengths but it hadn't quite sunk in

I get it now B)

[popshire 0]

if my plants survive and start to smell i might consider this for my grow...thanks for such a good idea

Edited January 25, 2013 by distracted

[FAZZ711 0]

Thanks you probly saved me and a lot of other peopl a lot of cash

[Napolean 0]

HOW LONG DOES THE ACTUAL FILTER HAVE TO BE PLEASE MATE SO I HAVE A ROGUH IDEA?

[distracted 27,593]

HOW LONG DOES THE ACTUAL FILTER HAVE TO BE PLEASE MATE SO I HAVE A ROGUH IDEA?

The one decribed at the beginning of this post is 14 inches, but it can be any lenght you want I suppose. The dimensions given were used to make my filter which works great for my 6" fan.

[Napolean 0]

Ok mate i see, thanks.

Did you have to put something on the bottom of the inside tube to stick to the metal pie tray, cos it seems pretty tricky to glue a thin frame to get a sturdy fix to a flat object.

I was thinking that maybe a bottom of a plant pot about an inch high could be glued to the end of the tube and then onto the tray to make life a little easier.

Also..... when you mention that the plant pot thats inserted into the 6" tube has to be cut down so that there is only half an inch inside. could this also be done by inserting the whole plant pot in there and just cutting the base of it off or am i mising something?

thanks mate

Edited February 10, 2007 by Napolean