New Grower Mars hydro

[Needtoknowautos]

You've already talked me into buying a third lol. I'm confused about some lingo, forgive my rookie ass, but what is 1200+ ppfd? And why would four be less efficient than three?

 

[Atulip]

photosynthetic photon flux density or ppfd is the average par of your grow space. If the light was perfectly evenly distributed, 1200ppfd=1200par at every point.

800-900ppfd is optimal for efficient flowering, most available light is getting used for photosynthesis and getting down in the canopy well. ~1200ppfd is where you start getting more light than the plant really needs and more of its wasted. 2000ppfd is like a bright sunny day at its peak though. So it's hard to actually bleach them(usually just powerful lights too close). But it's like this. If in the same space 270w of led might get you 250g(.9gpw), or 400w might get 400g(1gpw), then 540w might get you 450g(.8gpw). At a certain point you start getting deminishing returns for what light you're adding, and more space/plants would be the a better investment than more light.

I'm just estimating most of these numbers and basing 1w of mars led to 1w of hps. The gpw numbers are just estimating with a baseline of 1gpw for optimal conditions. My ppfd numbers are based off what most growers use for optimal conditions. Very similar to the "50 watts per sq ft" (Which also happens to be 3x mars300(135w each) for 8 sq st)

 

[Atulip]

I'm flying on some SS Dark Devil so I'm just gonna dump more info here.

Here's the chart I had seen before on ppfd and photosynthesis. Credits to tastyled owner for this chart.

Basically shows that around the 800ppfd area, photosynthesis barely increases from that point on. The main benefit for increasing total light at that point is better spread. You may be 1000par in the center, 600 at the outer(800ppfd average with good spread). Compared to 1500 in the center and 900 in the outer(1200ppfd with good spread). You sacrifice overall efficiency to try to max out the possible yield in the space. Typically better to go for more space(if possible) in that situation.

 

[SOUR JERZY]

the more the lights the better no doubt .... i only have one old mars 300w in my grow and i think im doing pretty good and i cfl veg my plant the whole time .....i keep them like 12 inchs from the tops in flower 16 inchs in veg like 20 inchs for the....you should be fine the ones under the lights always get the biggest bud ...make sure you fim them cause topping only gives you 2 colas if you fim it 3 colas each time before it starts to flower good you will get at least 12 top colas.....
i will be getting one more for sure ........i had this collecting dust in my closet boy was i wrong listening to all the haters back in the day .....

 

[perryated]

the more the lights the better no doubt .... i only have one old mars 300w in my grow and i think im doing pretty good and i cfl veg my plant the whole time .....i keep them like 12 inchs from the tops in flower 16 inchs in veg like 20 inchs for the....you should be fine the ones under the lights always get the biggest bud ...make sure you fim them cause topping only gives you 2 colas if you fim it 3 colas each time before it starts to flower good you will get at least 12 top colas.....
i will be getting one more for sure ........i had this collecting dust in my closet boy was i wrong listening to all the haters back in the day .....

nice to see some one happy with theres as well this is my first auto led grow and so far i am very pleased with my 2 mars hydro 300w

 

[cc2arms]

60 x 5 watt chips(the ones sold by mars hydro on eBay), the older model mars hydro 300 is 100x3.

2'x4' is doable with 2x mars300, put each in the center of a 2'x2' area and hang it 18" to get a good spread. Or drop it to 12". 18" should be the best overall use of the light in that space, but if you don't have buds all the way to the walls of your space, I'd go 12" to get more concentration of light on the plants.

Iirc mars uses mostly 90° leds. 12" high and 2'x2', the outer rim would be about 50% of the light output of the center. Raising it to 18" should be about 70-75% of the center(at a sacrifice of center light intensity)

Here's quick question, you'll notice in pic I angled my 2 leds. My logic was that by doing so I could maximize the overlap or spread of both the lights. Does this seem smart? I am not a new grower, but this is my 1st with LEDS and unfortunately I have had nothing but problemsView media item 6377

 

[Atulip]

Looks like it's just concentrating the light in the middle and too little on the side. Angled lighting like that is usually what'd your see when someones trying to light up a single big Christmas tree shaped plant.

If you can pick up a cheap lux meter on eBay or something you can test different light arrangements to see which gets the spread you want. I break out the thing everytime I adjust lights for height to make sure I'm getting the spread I want.