Help with high temps in my PC case!

[distagon]

This is my first real attempt at growing. I've got one White Dwarf auto plant under 75 watts of CFLs - she's about 2 weeks old, looking pretty good and starting to stink just a little. I fashioned a new carbon scrubber which seems to be working pretty well for now - it's just proving a bit much for my CPU fan.

I've got one 140mm Antec Tricool fan running at full speed, which is about 95cfm, and a static pressure of ~1.6. I think the low static pressure is what's holding it back. My temps are around the low 90s....how much longer will my plant continue to do well under these temps.

I was researching other fans, but can't seem to find another 140mm fan with high static pressure. My other thought would be to put an old 120mm case fan on low speed blowing on the lights. I'm just worried if I do that, It'll mess up the negative pressure of the box.

Any thoughts?

 

[ukganjafarmer]

personaly i have grown from seed to harvest in higher temps than 90f, its far from ideal but i certainly dont think it will kill your plants probaly just slow growth a little?

 

[thehappyguy]

what type of carbon filter are you using?

a 120mm fan between the lights and the canopy would help with the plants not getting hit with as much heat, but that heat still needs to leave the box somehow

 

[Maj.Cottonmouth]

I don't do micro grows but I have read on here about people who stack PC fans together to help overcome static pressure. Do you have another fan that you can attach so it is helping pull or push the air? Make sure the air flow is going the same direction on both fans and from my experience with cooling PCs I would recommend a pack of small zip ties for attaching fans.

 

[Fuzz420]

How thick is the carbon layer around the fan?Try decreasing the amount of carbon to increase airflow

 

[Harvest]

http://www.tigerdirect.com/applications/category/category_tlc.asp?CatId=99&name=Cooling-Products

 

[Scrogerman]

75w CFL & your Cab-Temps are in the low 90's, you must live in a hot country ah?
CFL's dont give off alot of heat & are easy to keep cool, im struggling to see why you have this heat problem. What is the temp in the room that you have your PC Cab in? Can you cool the room temp down? Have you considered using plexi-glass or tempered-glass in front of the light/heat source, that should do the trick, also stacking fans in series/parallel will help with your cab static presure.

 

[VerdantGreen]

scrogerman hit the nail on the head, the first thing you should do is try to cool your ambient room temps or move it to somewhere cooler, or run the lights during the night when it may be cooler also.

 

[grow1620]

can you show a diagram of your airflow and filter and stuff? I use smaller fans and have no problem pushing through small filters with them...perhaps a differnt filter design would help?

..and these guys are absolutely right about ambient temps...if you can't cool your bedroom or w/e putting it on the floor or in a corner can help with temps, as well as pointing a deskfan or something at it.

also how are you measuring your temps? measuring in the light will give you a false reading and will usually show 5-10 degrees hotter than it actually is. Try to put your thermometer in the shade and let us know those temps too. 90 really isn't too incredibly high, of course 78 or so would be much better...but as long as you keep them well watered and they have a break form the heat once and a while (lights out) they should be ok. Definitely try to get it cooler though of course!

edit: is your fan running at 12volts? if you're using a phonecharger or something it will run it a little slower...

 

[distagon]

I'm back with a picture of my setup...

So my 140mm exhaust fan is mounted in the top of the case. I just took a tupperware container, cut the bottom out, put a screen in, and filled it with about 3/4" of activated carbon. It does seem to be controlling the smell - although we'll see how well it works when it's in flower.

I have two 120mm intakes at the front of the case - I'm using some aquarium carbon sheets in front to help block the light - although it still glows like hell. I need to work on that as it's probably the biggest giveaway at the moment. This case, an Antec 300, has proven to be a real bitch to work with - so many nooks and crannies it's impossible to seal all the cracks.

You can see where my digital thermometer is mounted on the wall....you think that's giving me a good reading?

Also, I have noticed some burning of some of the older leaf tips. It showed up after my first feeding on day 10 or so, so I didn't think much of it. The new growth seems to be looking good, but I'm starting to wonder that tip burn was because of the heat issue.

Thanks for the watering tip - I've probably been too careful about overwatering given my heat situation, waiting til the soil surface is totally dry and hte pot is fairly light before giving it a good drink.

And the ambient temps in my apartment today are probably around 67 F, and the thermometer in the case reads 89. Warmer temps are coming too so I'll have to figure this out.

For one plant (indica, auto), how thick of a layer of carbon would I need to control the smell?


thanks for the help

cheers

 

[grow1620]

sorry bud, not seeing the picture, there's a link in my sig of how to do it. and make sure your gallery is set to public not private.

I use a pencil holder type carbon filter...works like a charm but it needs a little room. sounds like you're using a "sugarbear" type filter...perhaps you don't have enough surface area to disperse the air pressure? with a carbon filter you should try to have as much surface area as possible..the more you have, the more efficient your carbon filtering will be.

Your leaf tips could be overfeeding...I usually don't give new seedling any ferts till I actually see some yellowing leaves or other deficiancies. IMO seedlings are just too delicate, clones however are a different story. It also could be the heat too as you said. Keep an eye on them and if the leaves begin to curl down then it's probably nute burn, but if the edges of the leaves and the teeth are curling up, then it's heat stress.

If your plants are heat stressed then the leaves will try to kinda fold up and the teeth will point up, this is the plant trying to reduce it surface area so that it won't transpire (sweat) as much and also to try to reduce the light/heat it's subjected to.

I've built plenty of pc and other small cabs, if you need suggestions to improve airflow...just get that pic up and we'll see what we can figure out.

Thickness of your carbon filter is really dependent on your surface area of your filter as well as your static pressure...my filters are anywhere from 1/4 inch thick to 1 inch thick...depending on surface area and airflow, as well as whether it's a flowering or veg cab.

 

[distagon]

Hey...I changed my gallery to public. Any luck seeing that pic?

Also, about my filter: I tried making a pencil holder filter, but it was much smaller than the 120mm fan I was mounting it to, and it seemed really hard to make sure the fan was pulling only through carbon. The idea I made was basically a shrunken, simplified version of RedGreenery's tupperware scrubber for his Rubbermaid grows.

Another thing I'm noticing which I'm curious about: It seems like with the filter attached, my fan is only exhausting around the perimeter of the blades. In the center of the fan there is actually suction. Is this normal?

 

[grow1620]

yeh i see the pic now...still kinda hard to see ..lol. maybe take one of your input fans (the lower one) and add it to the filter..so it's like fan-->filter-->fan. sleek air flow is most important. I'm gonna go draw a pic.

nothin special really..just showing how to switch fans...just drew the pencil style one cuz I like it better . the zigzaggy things are scrubninja lighttrap thingies, just hit the link in his sig to check em out. also if you did dual fans like that on the filter you'd have to build a lil plenum (sp?) box to direct airflow...just kinda a lil box with fans on each side and the filter between...


sorry gtg. ... also i dont get your filter does it pull airflow from underneath? or from the side closest to the bulbs?