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dp#luver
22-10-11, 05:27 PM
i have a 400w hps that im looking to pu to wok in quite a large room.what amount of space will this light cover and what kind of extraction should i be looking at if eny??im open to eny additional advice on increase my yeild.experiance is the best teacher

Master Poet
22-10-11, 05:28 PM
A 400W HPS/MH will cover 1m3.

Anonymiss
22-10-11, 05:37 PM
What Poet said.

But if you want maximum illuminance (and so possibly better yields) then you might consider reducing the area, down to a minimum of about 0.5 m² (70 cm x 70 cm).

Woody J
23-10-11, 12:15 PM
To get anything like a decent yield, you need 5,000 lumens per sq ft while flowering. A 400W HPS will emit around 55,000 lumens, dual spectrum slightly higher. So you are looking at 11 sq ft.
Both Poet and Anonymiss were right as well though! I would never look to use a 400W in an area larger than 1sqM but if in a tent for example, 70 x 70 would be just perfect.

The key is to partition the space with either a tent or boarding or something, White poly over a wimple wooden frame is the method I have used for a long time.
Enclosing the space allows you to control the airflow, humidity and temps much better as well as confining the light and maximising the refective luminescence (my big word for today)

Look to exchange the air in the space between 1 and 4x per minute and you must have fresh air coming into the space, even if it is just a flap that allows air in.
W

dp#luver
24-10-11, 03:09 PM
so you dont think i need to go all out on the extraction for this one???im thinking of adding a few flourecents.eny thoughts or tips on that?

_Whisperer
24-10-11, 03:27 PM
I had a 400w hps covering my 1.2x1.2 m grow tent with 5 plants... I did get 9oz which I don't think is bad for my 1st grow... saying that the standard shade wasn't really up to the job of covering the edges and corners so I'd say neither was the light, But it will certainly do and I'm keeping it for my next grow... I'll probably upgrade to a 600w after a few more grows.

Mr Swilly
24-10-11, 03:40 PM
Perfect in a one metre tent. I used to haul a lot more in that tent than in my drobe using the same light, which was about 1mx0.3m using a cooltube which was bang on top of em vs a diamond reflector in the tent.

Mr_Bimble
24-10-11, 09:43 PM
1M*1M tent + 400W dual spectrum will work nicely with a good quality shade - I've got a diamond, it gives a good spread but retains the heat more them i'd like, thinking of switching to a parabolic when I've got a few more £££ spare.

Heat's more manageble with a 400W so I can get away with a passive intake.

Woody J
25-10-11, 01:12 PM
You do need extraction in the space.
When I said "air exchange", this means extracting stale, hot, CO2 depleted air and bringing in fresh air.
Something between a 120M3/h and 480M3/h extractor fan with Carbon filter will give you between 1 & 4 air exchanges per min.
You will not get away without using one.
As for fluoro's, If you have to buy them, dont, buy a bigger HPS!
When it comes to purchase and running costs, you get more light from a HPS than fluoro's. Adding 2 x 36W strip lights will gain about 1300 lumens, which, to be honest, isnt worth bothering with in that sized space.
More light is more light but when you factor in the cost and heat, a 20W cfl puts out more light.
W

Anonymiss
25-10-11, 01:26 PM
Adding 2 x 36W strip lights will gain about 1300 lumens

I don't often disagree with you (this is probably the first time), but I think that statement is wrong.

A single 36 Watt T8 will produce around 3,350 lumens. A 35 Watt T5 HE (or NO) is about 3,650 lumens. T5 HO is less efficient, and a 39 Watt tube will give about 3,500 lumens.

(All values are typical of Osram LUMILUX lamps.)