DIY Passive cooling with PIN Heatsinks SST120 and SST140
- Thread starter robincnn
- Start date
ttystikk
Well-Known Member
Cold temps? How cold? I'm having a similar issue.
ttystikk
Well-Known Member
Interesting. I just checked my LED rack; 73F while it's running. I want it to be ten degrees warmer but the air handler's placement is making that difficult.
Growmau5
Well-Known Member
@ttystikk my latest run has been a very humbling experience with this high PPFD. Just when I think I am becoming some kind of expert, this wonderful plant schools my ass.
So let me ask you: on CO2 do you believe in 1500ppm lights on to lights off. Or do you practice any of the nuances that we often read about such as:
-delay CO2 enrichment until 30-60mins after the beginning of the photoperiod
-begin with 1000ppm for the first 14-21 days of the flowering period and then ramp up to 1200-1500ppm
-or any other experience you can share with CO2 & COBs
Also, does anyone have a vapor pressure deficit resource that specifically discusses VPD in relation to co2 levels with cannabis?
So let me ask you: on CO2 do you believe in 1500ppm lights on to lights off. Or do you practice any of the nuances that we often read about such as:
-delay CO2 enrichment until 30-60mins after the beginning of the photoperiod
-begin with 1000ppm for the first 14-21 days of the flowering period and then ramp up to 1200-1500ppm
-or any other experience you can share with CO2 & COBs
Also, does anyone have a vapor pressure deficit resource that specifically discusses VPD in relation to co2 levels with cannabis?
cdgmoney250
Well-Known Member
No resources here, but I've been trying to keep my environment within the 'acceptable' range of VPD, while simultaneously trying to keep leaf temps high enough to actually photosynthesize under high PPFD conditions and high CO2 levels. The closer all the parameters are to 'ideal' the plants seem to respond better to the higher irradiance (less stress).
Just my 2 cents.
Just my 2 cents.
ttystikk
Well-Known Member
I haven't played with a lot of variability with my co2 enrichment intentionally, but my tanks do pop pretty quickly and then it might be a day before I get another one in.
I haven't seen any VPD vs CO2 PPM resources. My suspicion is that since leaf stomata must be open for CO2 exchange to occur, VPD needs to be on point for that to happen.
robincnn
Well-Known Member
Why do you like the square once. They get messed up in shipping.pins too thin and hard to package
ok i will get some for you next month.
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Airwalker16
Well-Known Member
Because these are square shaped pcbs. How many watts are they good for again? These are 50watts a piece.
robincnn
Well-Known Member
80W total LED watts
@Stephenj37826 Johnson Grow Lights will sell 36V Cree 3590 3500K CD at wholesale prices next week.
I will update here as soon as they are available or i have more information on prices.
Airwalker16
Well-Known Member
I don't mind bending them back in to place.
Airwalker16
Well-Known Member
Oh peeeerfect.
CoB_nUt
Well-Known Member
Thanks @ttystikk, @Growmau5 and @bobby g for those numbers and advice. I got some light bleaching and some light stress from having the 3590's too close. Moved them up to 16" and the plants responded well. The 3070's are still 10-12" above the canopy without issue. I was shooting for 1000 ppfd with hopes of falling in the 900 and up range. I figure once the 3rd bar is built, i'll Be able to dim the space to the plants liking if need be. I'm nit master grower by any means, I just try to grow happy,healthy plants from start to finish k.i.s.s. style.
RuRu.The.Half.Elf
Well-Known Member
The imagery makes me want an icecream sammich while sitting on the beach.
RuRu.The.Half.Elf
Well-Known Member
And just pulled the trigger on 4x sst120 @ 3070.
One day soon I'll be growing again. Soon.. I hope.
One day soon I'll be growing again. Soon.. I hope.
PDX Joe
Well-Known Member
Hi Robin,
I have some graphite pads from Cutter and just sanded my Arctic heatsinks. I am wondering if this may cause a corrosion issue. Should I let the heatsinks sit out for awhile to build up an oxide film or maybe see if I can get them anodized? Thoughts?
Thanks!
JorgeGonzales
Well-Known Member
"In dry air and at normal temperatures, an aluminium oxide layer up to several millionths of a millimetre thick forms within minutes and during the course of the next few days grows to double or treble this thickness. Growth rate and thickness increase with increasing temperature...In moist air (for example aluminium parts used in building construction that are exposed to the weather), the oxide layer can reach a thickness of a thousandth of a millimetre, which is significantly more than in dry air."
http://www.aluinfo.de/index.php/alu-encyclopaedia.html?lid=79
Anyway, I wouldn't sweat it. You really need metal grinding on metal in an oxygen-free environment to get galvanic corrosion.
PDX Joe
Well-Known Member
It almost sounds like you could introduce hot steam and get a thicker oxide layer before installing the COBs. I wonder though about the contact of the steel COB holder with the aluminum and with the presence of grow room humidity could cause galvanic corrosion? Seems like anodizing could be an extra precaution against this? Northern Grow Lights and others selling the pin heatsinks must be anodizing them for a reason... right?
robincnn
Well-Known Member
PDX Joe
Well-Known Member
Thanks. Does wiping the heatsink with alcohol before mounting the thermal compound remove the oxide layer or is this not an issue?