Trying to save a buck

[IJH]

How do everyone,

Quick question, I'm running a Spider Farmer SF2000 (2024 version), in a 2x4.

I've only got 2 auto flower plants under it at the moment, so lots of space and the plants (1 week old seedlings at the moment) are both directly under the light in the middle of the tent.

The guide for this light says to be at 50% and 24" above for this stage.

Considering the space does that mean I could turn the light to 25% and 12" away?

Whatever the answer I'd like to understand the logic behind it so I don't need to constantly bug people here.

Many thanks

 

[RGWD0202]

A higher light distance gives a larger spread, if you are only growing 2 no reason you couldn’t lower it and turn it down it just won’t hit edge to edge of your tent. I keep mine 15” as low as it can go until I get a few sets of leaves then start raising both light and intensity as I spread the plants apart as they grow.

 

[Newty]

If you're in the seedling stage, I recommend giving less then the recommended light from the manual. The manual recommendations are often wrong and why alot of growers end up with light and heat stress.
Start them around 25% at 24"-30" high, wait for them to tell you that they want more light, if you see stretching then turn up brightness or lower light height.

I'm in veg right now and my plants are only seeing 30% power (325 ppfd) at 24" high. My lights never go over 40% during the veg stage.

 

[IJH]

Thanks for the replies RGWD0202 & Newty.

That's good to know, it sort of made sense in my head but I wasn't sure, and as it's my first grow didn't want to screw things up by trying to optimise electrical use.

Cheers for the advise.

 

[RGWD0202]

I recommend downloading and using the Photone app it tells you Ppfd and dli, its free for android and I think it was 6.00 for apple, it’s not perfect by any means but will help get your light dialed in. I only use it as a guide. But make sure you make or buy a diffuser and buy the led version if you have an iPhone.

 

[ArtfulCodger]

Light intensity is proportional to the square of the distance from a point source, so halving the distance while halving the light output will increase the perceived intensity. It's not quite that simple, because an array of LEDs in a shiny tent isn't a point source, but it's directionally right. Another thing to consider is that we grow in three dimensions, not two. It is certainly possible to put the same light intensity on your tops with a closer light set to a lower output, but that happens at the cost of canopy depth and horizontal coverage.

I started with an SF2000 in a 2x4, and upgraded to a stronger light after one grow. 25W/ft² in a small form factor fixture works OK for veg, but it wasn't enough for flower, in my experience.

 

[IJH]

Thanks, I got the PPFD Meter app from Play store just because of the permissions thing. A little learning and then I'll get to using it. Thanks for the tip.

I recommend downloading and using the Photone app it tells you Ppfd and dli, its free for android and I think it was 6.00 for apple, it’s not perfect by any means but will help get your light dialed in. I only use it as a guide. But make sure you make or buy a diffuser and buy the led version if you have an iPhone.

 

[IJH]

Light intensity is proportional to the square of the distance from a point source, so halving the distance while halving the light output will increase the perceived intensity. It's not quite that simple, because an array of LEDs in a shiny tent isn't a point source, but it's directionally right. Another thing to consider is that we grow in three dimensions, not two. It is certainly possible to put the same light intensity on your tops with a closer light set to a lower output, but that happens at the cost of canopy depth and horizontal coverage.

I started with an SF2000 in a 2x4, and upgraded to a stronger light after one grow. 25W/ft² in a small form factor fixture works OK for veg, but it wasn't enough for flower, in my experience.

Thanks I appreciate the detailed response, where I live we can only grow 3 plants per person, and have 50g dried per person, the Mrs doesn't really partake, so if I can get 100g from 2 plants I'll be well chuffed, I'm not looking to maximise yield, as I'm a resident not citizen of the country where I live and don't want any problems, so if I can produce 100g of good quality bud every 3 months that'll do, I'm thinking I'll only do autos as the speed and lower yields are perfect for me and the laws I need to work within. Do you think the sf2000 is good enough for that?

 

[ArtfulCodger]

I'm thinking I'll only do autos as the speed and lower yields are perfect for me and the laws I need to work within. Do you think the sf2000 is good enough for that?

That would be less than half an ounce per square foot of flower space. The SF2K can do that.

 

[LoveGrowingIt]

It may be worth mentioning that light intensity has a lot to do with how tall plants grow.

 

[Natep]

I keep my lights as far away as possible. I start as dim as possible. When the leaves look like they are praying right before lights I turn it up.