is the optimum height of a hps 3ft???

what about if the hps was in a cooltube?

or is the pentration dependant on the wattage of the hps? 250/400/600

all depends on wattage and temps mate!
i have a 400w that i get within 8-10" of the canopy with the aid of a couple of pc fans!
T1

Should sort you out

Usually 12-18" for 400w and 18-24" for 600w although a fan blowing under the lamp allows you to get closer.
I have 600w in a cooltube and go under 12" distance (I could get a lot closer if I wanted, heat is not an issue), the glass probably reduces the lumen output so it works out the same as 18" without the glass maybe.

Had my 400w HID's as low as 6" with a gale blowing off the fans and humidity boosted.

Normally 8-10" though. Depends from where your Ints are being sourced from, so it can and does vary.

According to the chart, i think the closer to 6 inches the better, as long as you can deal with temps.

i managed to get a 400w hps (open reflector) 10-12 inches from the plant tops with a fan blowing in between.

it is a small space- max temps 31c. no burning

Prob be better if lights-on was during night and lights-off was in day

sorry i wrote the questions wrong, i meant what is the optimum hieght of the plants when using a 250watt or 400watt. as in how far down will the light penetrate as in 3ft down?

sorry i structure my questions really poorly

workin wif 3 Foot plants (4foot wif pot)
id try to keep the light about 40cm from top ov the plant at all times thats usein a 600w tho, so ya might be able to get abit closer wif a 400w but good ventilation is needed to...

ok let me rephrase it one more time, what is the penetration depth of a hps? 3ft...4ft

even with a cool tube ya cant get too close 9" with 400 12" with 600


f-h

I think a 600w has a 3ft range, 2ft above canopy....1ft of penetration below canopy.
My 1000w is about 4ft range.
You could also get a light meter.

BULLET

Can anybody please tell me what is better for flowering a standard hps or a dual spectrum hps????????
thanks guys

I think the effectiveness of a 400w HPS decreases rapidly around 90cms from the bulb....

...roughly .....

Laz

dual

thanks for the fast reply mate nice one

so a 600watt is best 2 ft away from the canopy which would mean that scrog/sog is a must with 12 inch long buds?

unless the 600 is in a cooltube so maybe 1.2-1.5ft away with 1.5ft buds

Hey guys,

I was speaking with some v.experienced growers the other day. I explained that i was aiming to get my lamp as close as poss in order to get max light efficiency without burning the leaves. By using fans or an active intake.

They all advised that there is no need to get more fans, as there should be at least 1-2ft gap between lamp and canopy or the plants will burn and suffer heat stess.
They insisted never closer than 1ft. As the plant want to grow/reach up towards heat/light. not be hindered by heat from above. As they can grow 10inches a day.

Now lights loosing efficiency over distance makes logical sense to me.

But im not sure which way would benefit the plants most?

Anyone?

10 inches a day ? - they were tugging yer strings

I imagine 12 inches would be a decent distance for a 400 watt lamp - there is a balance between the useable intensity and lamp coverage.

9 inches is what works with my 250 watt lamps in my particular space.

here we go flowering heights that work well.

250wt - 25cm
400wt= 40cm
600wt= 60cm

in veg add about 15cm to be sure you cover your room from corner to corner, then lower to ideal height when flowering or leave the light where it is then allow the plants to grow that 15cm into light..

the optimum height is as close as you can get it to the plants whilst still now shading off any colas by the center ones I just use the back of my hand to messure if it's too hot or not ,

if I can have my hand there for a min or two comfortably without too much warmth then the plants ain't gona have an issue eigther

The optimun height not only depends of bulb's wattage. Its strongly related to reflector's footprint and shape. The best height is very different for a security light reflector or a double parabolic reflector. If you put a concentrated reflector to close of plants, then there will be too little light at the edges of the grow space, reducing total yield.

Very true, it also depends on how well your grow enviro is coated with reflective material.

Think we missed that important fact. Mylar does the job very nicely on my 400w HID set-up in a 2.7 m3 enviro.

good and intetresting thred,

im using a grolux 400w HPS,
in my experiance much closer than 12 inches results in visible heat stress, much more than 24 inches is wasted light...in flower that is, in veg, 2.5 foot is fine.

that said, my reflector is about 2 foot square (which pretty much covers my entire grow space), umbrella type with reasonably good cooling.

the biggest problem, i find, is when the main cola gets big, the lower bud sites lose out, because the light has to be that much further away.
this can be rectified by tying a cord/string rond the main stalk and bending it over to bring it down to the level of the rest of the growth, allowing the light to be lower, and all bud sites to get max light

I've had a 250w hps about 6" away from the tops, with a fan blowing across the tops too, although I'm happier with the bulb about 8-9" away.



Another opinion.

hi my 400s ar6inch from top of plants ,,,,,,,,,but some strains take the heat better than others imho,, happy growing

Oops - just read what oldtimer said about the bog standard son-t's I've been using.

I use the Adjusta-shade lighting system with the heat spreader and 600Watt bulbs. I keep my light about 6-8" from the canopy without any problems, I couldnt belive how good the system was when I set it up (all be it a little expesive) But the design stresses why.

[attachmentid=119805]

What was that?

That they make a lot less light than the son-t plus.

(mind you I'm running 90 watts per square foot .... )

(so tempting to sneak lamp orders in with other stuff from screwfix)

I know what works for me.

Just forwarding a bit of growing knowledge, maybe.

Grow well.

What does OT1 say about Son-T's then compostverte ?

And more importantly WHERE[can't find it] ?

http://www.uk420.com/boards/index.php?showtopic=18512



except they're roughly twice the price
.

you just had me going through the bin looking for the boxes to check what mine are, son t plus.

I'm off to wash god knows what off my hands

It's OK i've got a Son-T +,but i'm going to add a MH to it.