PLL Club. (if you don't know, now you know)

[j6p]

Hephaestus, is there any ventilation above the plexi heat shield, where the lights are? If not, how hot is that top area around the lights? Apparently no overheating problems above the shield? TIA

 

[Hephaestus]

If you look back left - 3/4" pvc intake... Back right - exhaust holes through regular cooling fan.

Temps run in the mid 90s - shouldn't be an issue, my coralife fixtures run well over 100.

 

[dymaxion grow]

I'm using 1/4" plexi to separate mine
Cabinet runs about 7 degrees cooler with the plexi in place - more than makes up for the maybe 20-30 lumens lost...

Is it any special kind of plexi or just the regular clear kind? How close is it to your lights?

Thanks so much for your help.

 

[Hephaestus]

Mines just stuff I found in the recycling bin (thus its use in project reject) Product is called makrolon - http://plastics.bayer.com/plastics/emea/en/product/makrolon/Product_description.html

I've got 2" between sheild and mounting surface - puts the bulbs ~1" away from the shield.

 

[dymaxion grow]

Hmmm, that makrolon looks good but is it widely available(especially to be cut down for cabinet use)? Would you recommend any other material?

 

[Hephaestus]

recycled it... so no clue... I've still got a few big hunks sitting here - how much do ya need?

Typically Acrylic and plexi can easily be sourced locally - sign shops, GE plastics, etc all tend to have sheets available

 

[j6p]

You're going to loose some lumens anytime you put anything between the bulbs and plants... That said... I'm using 1/4" plexi to separate mine - plexi/acrylic is more efficient as a separation than glass (doesn't allow the heat to radiate through as much). I think the loss of a few lumens (we're talking minimal %ages here) is more than compensated by the reduced cooling needs...



Cabinet runs about 7 degrees cooler with the plexi in place - more than makes up for the maybe 20-30 lumens lost...

The shield looks good. Plexi is much more effective than glass for blocking heat (below), it is 50% lighter than glass, is easier to cut/work with, and is more impact resistant than glass.

In the event of fire, plexi is flammable. Including an automatic fire suppression device is therefore recommended for safety (always a good practice in any event).

Heat Blocking Plexi vs Glass
Typical values for the Coefficient of Thermal Conductivity
* Acrylic: 1.3 BTU/(hr-ft2)(F/inch)
* Glass: 5.3 BTU/(hr-ft2)(F/inch)

Physical Properties Plexi
* Melting Point: 130-140 degrees Celsius (266F)
Upon reaching its melting point, it can be formed formed or put into any shape.
* Boiling Point: 200 degrees Celsius (392F)
* Transparency: 92% total white light transmittance, they highest physically possible.
* Weight: Less than 50% as heavy as glass.
* Insoluble in liquids.
* Electrical Properties: Surface Resistivity is on the high side (does not conduct electricity well) making it a good insulator.
* Combustibility: Temperature of Spontaneous Combustion (self ignition) is in between 850 and 869 degrees Fahrenheit.
* Temperature at Ignition in Presence of Flame is in between 550 and 570 degrees Fahrenheit.

Upon ignition, Plexiglass burns vigorously and generates intense heat.

https://chempolymerproject.wikispaces.com/Plexiglass-E-MgEb

 

[Hephaestus]

For me I'm not worried too much about fire supression - it's an aluminum cabinet... Hopefully if something was to go wrong - it'd stay contained within the cabinet.

 

[dymaxion grow]

recycled it... so no clue... I've still got a few big hunks sitting here - how much do ya need?

Typically Acrylic and plexi can easily be sourced locally - sign shops, GE plastics, etc all tend to have sheets available

I suppose enough to make a heat shield to cover a 2ft x 1.5 ft area. I can check around the local shops. And if need be, i'll get it from you and pay you!

 

[Hephaestus]

Oh I could cover that about 10x over with the scrap I have Let me know - we can work something out... let me know where in the world you are - and I'll see what shipping would run ya...

 

[rives]

PL-L vs T5 F24HO

PL-L vs T5 F24HO

I originally posted this in the growroom design area, but didn't get any replies. I'm putting together a new cab (refrigerator grow) and am having difficulty deciding between 55 watt PL-L lamps and T5 F24HO lamps. I know that the PL-L has the lumen advantage (approximately 5000 vs 4000 for (2) F24HO's), but it seems to me that the linear fluorescent lamps run cooler. I plan on remote mounting the ballasts outside of the cabinet to keep that heat source out, but the PL-L's generate a lot of heat near the base. Without a sample of each in hand, I can't tell how much difference there is between the two styles. I can fit enough F24HO's to offset the lumen advantage of the PL-Ls. I'd appreciate hearing from anyone that has experience with these lamps

Thanks.

 

[Hephaestus]

Personal experience - My T5 24wHO run about as hot as my 55w PLL's.

t5's you can get better reflectors to put more lumens down (less loss from reflecting off the bulb) but there's some decent reflectors for PLLs as well...

Don't forget you can now get 80w PL-L's if you have room for that extra inch of bulb; That's going to be the hot ticket coming up.

If heat's a major concern (which it will be in a fridge) Look up on the page, see how I've used a heatshield to separate the lamp heat from the cabinet - its easy added and doesn't necessarily need to be powered if you think about heat rising (I was doing some testing in my fridge recently - downturned intake, long (10") upturned outlet got a great cooling flow without needing fans...

 

[Boleman]

3rd week in on round 2 of the Mary Purpins. Click to enlarge. 72 watts. Sweetness.

Notice in the last pic, that even with only 72 watts of PLL lights, the flowers are all the way to the screen. A full 11 inches below my lights and 10 inches above my canopy.

 

[Hephaestus]

Boleman - your work always impresses the shit outta me!

 

[thehappyguy]

i'll have to make a new cab to fit PL-Ls but i want to so bad...i actually already have my eyes on one, i just have to spring for it!

 

[inphu510n]

I've been following this thread for a bit and am very interested in using PL-L's for a veg cab. So, at this point I'm not really IN the PL-L club but seeing as how you guys are the most experienced with these little beauties, I figured I'd throw out a question or two.

I haven't seen much discussion here about color spectrum. I've seen talk about using aquatic/actinic bulbs in the 10k range and I'm not sure why. Isn't 10k WAY too high for photosynthesis?

I'm also quite curious what you guys think about using a 420nm/460nm bulb like this one. Looking at the photosynthetic spectrum these nm values hit close to the peaks for vegetative growth. Definitely closer than using a 6400k or 6500k bulb. Apparently mj's peak absorption for veg is 439nm and 469nm.
What we really need is a 5500k bulb.

EDIT:
Ok just looking at SunPaq's literature their 10k bulbs hit hard right around 450nm which seems good except that it's a massive peak. There's a big valley on either side of that peak. The rest of the spectrum produced by the bulb looks good for growth though.
Looking SunPaq's specs for their 420nm/460nm bulb it has an excellent punch between 400nm to 500nm plus a little bit beyond 500nm. If going by specs alone, this is THE bulb to get for veg. Check the PDF on the link.

 

[Hydro-Soil]

Ok just looking at SunPaq's literature their 10k bulbs hit hard right around 450nm which seems good except that it's a massive peak. There's a big valley on either side of that peak. The rest of the spectrum produced by the bulb looks good for growth though.

You'll find this with just about every type of Fluoro. No matter what the listed spectrum is... it's only a spike.

The general consensus (from all my reading over the years) is that the 10K and 03/Actinic lamps produce shorter internode length, thicker stems and increased side branching. Pretty dang good for mums.
On the other hand... a good 20$ 3000-5400K lamp will work just fine for about 2 years. I use the 5400K for my veg/mum chambers.

Stay Safe!

 

[ScrubNinja]

Peep my new thread, I'm vegging under a 55w 10,000k as of today to see how it goes. Only got one of them though

 

[Garuda]

My 2x55W PL-L cab:



The babes are 2 different phenotypes of Double Dutch at flowering day 50

edit: Some better Closeups:



May I come in?

Greetings,
Garuda.

 

[mexicangreen420]

cool, i have been tagging along on this thread not saying anything, reading up, researching. so i built myself a cab, i'll throw a pic up in a couple days when there is some green up in there.

she is 30wx36tx18d, about 3 square feet of usable flower space. went with 3x55w 2g11 PL-L, workhorse 8. i have 1-3000k, 1-3500k, 1-4100k, i plan on using the multi-spectrum approach. there are 3 trainwreck clones in there, and 2, week old seedlings, a white rhino and great white shark. i am only flowering the wreck. should be fun! for soil i am using ffof/light warrior, 50/50, RO water, biobizz all the way, and some old dark energy i have had for 4 years. everything looks great so far, thanks for posting so much info guys!!! scrub ninja, your cab is the shit, it made me wanna go for it with the PLL's. thanks!