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sandman420
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx] 1
#27461466 - 09/09/21 08:32 AM (2 years, 5 months ago) |
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yea yours is way worser lol
you just needed about 550 cfm...
Why is everyone strapping a 1tdu2 to everything?
also a 1tdu2 is 1 speed what you mean turned to low?
Edited by sandman420 (09/09/21 08:34 AM)
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sandman420
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Re: Help me troubleshoot my flow hood [Re: sandman420]
#27461470 - 09/09/21 08:40 AM (2 years, 5 months ago) |
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Oh I see you used a controller...1tdu2 says specifically not for speed controller FYI...
You said you have a 3" pack those have different what brand I'll look up the specccccccccccccs
but this filter is fucked sorry
Edited by sandman420 (09/09/21 08:41 AM)
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: sandman420]
#27461511 - 09/09/21 09:14 AM (2 years, 5 months ago) |
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I chose the 1tdu2 because after looking every day for a month straight I still never found a different blower where the math worked.
I was really concerned about getting a blower that wasn’t powerful enough, and every fan curve had me barely on the edge of enough.
Having actually put a flow hood together now I know that concern shouldn’t have been as big.
The filter is a Flanders Astrocel II which had the .99% rating meaning it was scan tested from the mfgr.
I also am aware the recommendation not to be used with a speed controller but a) couldn’t get it low enough by choking the intake (even almost completely), and b) have seen plenty of examples of people doing it anyway and it working out.
Are you saying the filter was fucked when I got it, and that’s why the uneven flow?
Or are you saying the overpowered fan somehow ruined it?
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sandman420
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx] 1
#27461551 - 09/09/21 09:45 AM (2 years, 5 months ago) |
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Man ... this brings me no joy alright but you kinda botched it. These astrocel ii 3" packs are just crazy low static pressure.

This filter runs only ~0.27" at 90 fpm... So you needed about 540 cfm @ only 0.47" when you account for a prefilter. (this filter is basically as resistant to air as a furnace filter, that is loosey goosey ! ) But you gave it 1120 cfm or so with the 1tdu2 at these pressures.
You probably have a crazy turbulent plenum from this huge fan and it may have loaded the filter unevenly if you ran it long like this. In that case the filter will never be able to have laminar flow. Having half the face sucking air is...concerning.
You can replace the fan with the proper one because as you can see even blocking 100% of the intake will only get you so far, and the speed controller isn't getting you there.
You need a fan that blows about ~500 cfm (when account for frame) @ 0.47" 1tdt8 on low would be a good choice. Or maybe high and ~quarter blocked.
Edited by sandman420 (09/09/21 09:50 AM)
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: sandman420]
#27461560 - 09/09/21 09:51 AM (2 years, 5 months ago) |
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I did see those early on but when I picked up the filter I went with the 1” wg that the sticker on the side says.
I could definitely try a lower powered fan..
Also for what it’s worth I never ran it at the full open 1202 cfm for more than a few seconds at a time before choking or lowering speed, no more than a minute total.
damn what a waste of time and effort
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sandman420
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx]
#27461577 - 09/09/21 10:01 AM (2 years, 5 months ago) |
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As you can see from that graphic static pressure is a function of airflow. So it may have said 1.0" at what CFM??? You can't just say a filter has 1" static pressure that doesnt make any sense without the speed or volume of air it is a totally useless number. That's what you have to look at and extrapolate the cfm at the speed you will use it. Or just look at the graphic they gave you. Expensive lesson I am sorry for you. Hopefully with the lower fan it will still work out.
Edited by sandman420 (09/09/21 10:04 AM)
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: sandman420]
#27461620 - 09/09/21 10:38 AM (2 years, 5 months ago) |
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It says 1” at 700 cfm 
with all my months of research and looking at graphs I threw it all out of the window when I got the filter and misunderstood the sticker.
I mean, I get it now.
I already boxed up the blower and submitted for a replacement. When the new one gets here I’ll update the thread, cross your fingers for me.
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx]
#27471527 - 09/17/21 09:29 AM (2 years, 4 months ago) |
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Just wanted to do my part for the forum and update this thread.
I exchanged the larger blower for a smaller one, mounted it up, and I still had similar uneven airflow issues.
After further inspection/troubleshooting I noticed that the front face of the filter was unsealed with silicone — I didn’t think I needed to because of a)how snug the fit was and b) I thought I had sealed those openings on the inside from the back when constructing the box.
My filter had a ‘flange construction’ as opposed to what we usually see here in the forum and on videos known as ‘box-style construction’. The flange meant it didn’t sit flush on its own so I had some tedious parts with the construction and it made sealing everything more intensive.
That being said, this fixed 90% of the issue.
Seeing how drastic a difference that made, I went ahead and sealed up my prefilter box as well. I hadn’t done it before then because I was still troubleshooting it and wanted the option to detach if I needed to get back in.
Sealing the prefilter box fixed the rest of my issues, except one tiny dead spot in the far upper left corner. I can’t seem to get that one worked out. I checked and re-sealed the area around it but it doesn’t look to be changing. Hoping it’s not going to be an issue but watching the smoke flow from around that area seems like it isn’t causing a disturbance.
I left some blank petris out open for 20 minutes or so, so hopefully they remain blanks over the next 3-4 days.
If they do, here I come bags 👍🤞
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sandman420
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx] 1
#27471561 - 09/17/21 10:02 AM (2 years, 4 months ago) |
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good luck with everything!
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: sandman420] 1
#27471589 - 09/17/21 10:43 AM (2 years, 4 months ago) |
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Hey sandman I do appreciate your help troubleshooting this with me 👍
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sandman420
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Re: Help me troubleshoot my flow hood [Re: dirtybirdx]
#27471637 - 09/17/21 11:24 AM (2 years, 4 months ago) |
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how big is the dead spot?
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dirtybirdx
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Re: Help me troubleshoot my flow hood [Re: sandman420] 1
#27474647 - 09/19/21 03:37 PM (2 years, 4 months ago) |
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I’d say it’s about ~2” x 2” in the top left hand corner
Agar plates which were left out for 30 mins or so in front of the hood are still clean today 4 days later …
I suppose that’s a good sign 🤩
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