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Cue
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Another flow hood question
#22247542 - 09/16/15 07:19 PM (8 years, 4 months ago) |
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I know this has been beaten to death, but I'm having issues with my flow hood and was hoping some of you more experienced folks could help me out. I did some gtg last week, and almost 75% are contaminated now. I'm really debating going back to using a SAB.
When running the hood without a prefilter, it almost knocks the flame out. When I have the prefilter on, the flame bends without flickering, but it's not more than 30 degrees. If I put the filter covering half of the intake, the flow is good on the top, but turbulent on the bottom.
Should I try a less intense filter? The one I use now is the black furnace filter from Home Depot. Or if there some other way I can even out the flow at the top and bottom of the hood with half of the prefilter on there.
Thanks.
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vagblast
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Re: Another flow hood question [Re: Cue]
#22247582 - 09/16/15 07:32 PM (8 years, 4 months ago) |
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I would assume u could use a less dense filter or maybe two really weak ones I do the same on my house ac unit. Not that it matters but don't they use the same kinda filters for a pre? Maybe bad advise... Sorry if so
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iSmkGrnBud
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Re: Another flow hood question [Re: vagblast]
#22247777 - 09/16/15 08:02 PM (8 years, 4 months ago) |
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I know most use the 3M Ultra Allergen 1250 as a pre-filter. I don't know if this would make any difference or not, I don't personally own one.
-------------------- iSmkGrnBud's Teks iSmkGrnBud's Wild Mushroom Finds  The Noob Forum's List of Teks “The probability of success is difficult to estimate; but if we never search the chance of success is zero.” -Giuseppe Cocconi
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vagblast
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Re: Another flow hood question [Re: iSmkGrnBud]
#22247810 - 09/16/15 08:08 PM (8 years, 4 months ago) |
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Quote:
iSmkGrnBud said: I know most use the 3M Ultra Allergen 1250 as a pre-filter. I don't know if this would make any difference or not, I don't personally own one. 
Yeah me either. Sryy. Hopefully someone will come along soon with experience and clear this up for op
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maddchef
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Re: Another flow hood question [Re: vagblast]
#22247866 - 09/16/15 08:18 PM (8 years, 4 months ago) |
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If you have a different rate of flow on top vs on the bottom then something is bad wrong. Your filter should develop a given amount of pressure behind it before it even "lets" air pass through.
-------------------- In the land of the blind, the one eyed man is king. All mushrooms are edible, but some only once..... Easier than cakes I do science and shit.
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Cue
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Re: Another flow hood question [Re: maddchef]
#22247967 - 09/16/15 08:31 PM (8 years, 4 months ago) |
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I should mention that with the prefilter, the flow appears uniform throughout. Regardless, just to make sure I'm not crazy, I'll check again tomorrow and post some pics of the airflow at various points.
I'm assuming that if air is passing through without pressure being built up, then it's the hepa filter itself that is faulty
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maddchef
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Re: Another flow hood question [Re: Cue]
#22250042 - 09/17/15 09:08 AM (8 years, 4 months ago) |
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With or without a pre filter it should still have the same static pressure before it allows a steady stream of air through.
Do you remember the stats for your filter? Ie: 1sp @400cfm etc?
-------------------- In the land of the blind, the one eyed man is king. All mushrooms are edible, but some only once..... Easier than cakes I do science and shit.
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maddchef
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Re: Another flow hood question [Re: maddchef]
#22250052 - 09/17/15 09:11 AM (8 years, 4 months ago) |
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If your filter is rated 0.25sp or something low then I could see this happening depending on how you have your blower mounted.
-------------------- In the land of the blind, the one eyed man is king. All mushrooms are edible, but some only once..... Easier than cakes I do science and shit.
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Cue
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Re: Another flow hood question [Re: maddchef]
#22252402 - 09/17/15 05:54 PM (8 years, 4 months ago) |
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It's an astrocel I. Resistance is 0.9 at 1000cfm. I have the blower (Dayton 1TDR7 485cfm) mounted on the top of the box.
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Cue
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Re: Another flow hood question [Re: Cue]
#22252462 - 09/17/15 06:04 PM (8 years, 4 months ago) |
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This is with the new, thinnest filter from HD
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Cue
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Re: Another flow hood question [Re: Cue]
#22252522 - 09/17/15 06:16 PM (8 years, 4 months ago) |
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Cue
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Re: Another flow hood question [Re: Cue]
#22252538 - 09/17/15 06:19 PM (8 years, 4 months ago) |
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I guess my question now would be is the slight fluctuation at the bottom going to cause an issue? Sorry for the multiple posts, was having issues getting the video in there
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micelio
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Re: Another flow hood question [Re: Cue]
#22252573 - 09/17/15 06:26 PM (8 years, 4 months ago) |
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My suggestion would be, place a few agar dishes in front of the hood and see if they come up contaminated..
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Cue
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Re: Another flow hood question [Re: micelio]
#22252603 - 09/17/15 06:32 PM (8 years, 4 months ago) |
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i guess I'll give that a shot. I've done agar work before in front of the hood with good success, but it was in another room. I'll have to report back. It is possible that the g2g I was working with was contaminated, but seems extremely unlikely considering they came from clean wedges and colonized within 7 days. Also, although my sterile technique is still undergoing improvement, I've never had the same levels of contamination as i have recently working with the hood.
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micelio
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Re: Another flow hood question [Re: Cue]
#22252717 - 09/17/15 06:53 PM (8 years, 4 months ago) |
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I think your a little shy on cfm..(485cfm..) If you don't have enough static pressure in your filter box your not going to have a laminar flow. That's what RR was saying..
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99.99
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Re: Another flow hood question [Re: micelio]
#22252760 - 09/17/15 07:03 PM (8 years, 4 months ago) |
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Hey this might not have any bering on your problems but i to had a hell of a a time with mine lately...turns out the hood was fine but I was using the synthetic filter disks for the top of the bottles and for some reason they would not sterilize in the pressure cooker I ended up buying bags and that relieved hundred percent of my problem
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blindingleaf
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Re: Another flow hood question [Re: micelio]
#22252789 - 09/17/15 07:09 PM (8 years, 4 months ago) |
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that video looks good enough to me 
i like it a little stronger than that, so i take pre filter off when working in front of it, and leave it on when i let it run for an hour before.
it made a difference in my contam rate, but the hood i have is only 1' tall, urs is 2' so u have more head room, so a slower flow is probably ok.
if ur blower is 485cfm @ free air, that is technically too low. u would want 485cfm at 1"SP for it to be pushing a minimum of 100FPM off of a 2x2 filter.
-------------------- A few thoughts on cultivation MICROBIAL HUSBANDRY!!!! The whole is greater than the sum of its parts
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micelio
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Re: Another flow hood question [Re: micelio]
#22252799 - 09/17/15 07:10 PM (8 years, 4 months ago) |
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I think you would be in a safe zone working right up against the filter.
Just a thought.. Try blocking off six inches of your filter with cardboard or something form the inside, and just not work in front of that area. It would shorten your working area but you would have laminar flow...
My filter 24"x24"x6" called for a 900cfm blower.. so I went to 1200cfm. and block off my blower intake for flow adjustment.. It's better to be over 20% to 30%..
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Cue
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Re: Another flow hood question [Re: micelio]
#22252941 - 09/17/15 07:35 PM (8 years, 4 months ago) |
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When I don't have the prefilter on there it almost blows the lighter right out (turbulent as hell). If I got the proper sized blower would the flow be more even? Ie : would the thing not be so turbulent that the lighter goes out?
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blindingleaf
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Re: Another flow hood question [Re: Cue]
#22253006 - 09/17/15 07:46 PM (8 years, 4 months ago) |
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Your flow is even enough from the video.
if ur plates start getting weird contamination around the perimeters or outside of the cultures, then i would start to worry.
stronger is generally better though.
-------------------- A few thoughts on cultivation MICROBIAL HUSBANDRY!!!! The whole is greater than the sum of its parts
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micelio
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Re: Another flow hood question [Re: Cue]
#22253172 - 09/17/15 08:17 PM (8 years, 4 months ago) |
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Is your pre-filter tape to your blower intake or do you have a pre-filter box on top of your blower with the pre-filter mounted to the side of it?
By having a pre-filter box you will increase your pre-filter area and will let more air flow through your system..
A cardboard box can be used as a prototype..
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