400w and light rails

Hello

How would you recommend a 400w digi light be when using a 4ft hydrofarm light rail?

thanks

No i wouldnt reccomend using a light mover along with a 400 watt light unless certian conditions were met,you'll end up with seriously stretched plants if your not carefull in your planning & set up because the light mover will be taking the light past its coverage area in most cases.

The only way i'd run a 4ft mover with a 400 watt light is if my space was no larger than 6ft long x 4ft wide & some serious thought went into capturing all reflective light possible,the reason i say this is because you'd need all the reflective light you can get,once the light makes its pass along the rail the center of the light will be 4ft away from the other end of the grow area,this will be a very shaded area most of the light cycle,this is where stretching comes into play.

It can be done with good results just remember that a 4oo watt light is only good for covering a 3ft x 3ft area,this translates into 18 inches of light space on both ends of the light,when the mover takes the light to its furthest point the center of the light will be twice the reccomended distance from the plants.

Just so you know i do use 4ft as well as 6 ft movers in my grows.

Thank you for the advice, but I still need to know how far to keep the rail, What I have growing is 4x5ft scrog with two 400w digis on two light rails with 3 sets of two lamp flouros each one with a blue lamp and a 10% uvb lamp all five lights run parallel to each other so that the HPS run inbetween the flouros so that the sides of the HPS are almost touching the sides of the flouro fixtures this way there is always available light to the plant with moments of higher intensity, I have been keeping the HPS around 8" above the tallest points and all through veg the plants responded well. I am currently toward the end of my 3rd week of flower and have nice development. however I have been noticing that the tops of the pistils are turning brown, and was wondering if this was a heat issue as the top can reach 95 when the lamp is directly overhead ( I am supplementing with co2 around 2000ppm) one other thing I am noticing that tips browning is also happening to plants not directly under the HPS so maybe it is another problem either way I would like to know what is the recommended distance for the these lamps with a rail.

Thank you

The pistils turning brown can be a few different things,too much heat,too little fertilizer,early finish strain ect....

Sounds to me that at 95 degrees its just too hot,i never let my light/canopy temps reach above 80 degrees,even with the movers.

i really disagree with that it could be true tho...i just purchased a light move for a hydro setup and i will be using a 400w the time around...the light is supposed to even out the cannapy and it only takes about 20 mins to reach from one side to the next...but i havent got to try mine out yet...but i have talked to many many growers and they like em

You have to keep all your plants at identically the same level and practically drag the top of them with the light down just low enough not to burn while it's moving.

cali-high said:

i really disagree with that it could be true tho...i just purchased a light move for a hydro setup and i will be using a 400w the time around...the light is supposed to even out the cannapy and it only takes about 20 mins to reach from one side to the next...but i havent got to try mine out yet...but i have talked to many many growers and they like em

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Been there & done that.

Most of what salesmen & manufacturers tell us about light movers is complete bullshit,i like my movers as well & i do use them but if you are buying a mover thinking your going to double your floor space or yeild your in for a big let down.

400 watt lights are too small for even a 4ft rail,a 400 watt light only covers a 3x3 area & this figure is not debatable its what the light will effectively cover,that figure comes out to 18 inches on both sides of the light,now when the rail makes its full run down the 4ft track how far away is the center of the bulb from the other end of the grow ?

Do the math here,the light takes 20 minutes to make a full run so that works out to 3 runs per hour,that also means that the ends of the grow are outside the effective light range 1/3 of the time every hour,correct ?

If you use a 4ft mover with a 400 watt light you will end up with stretched plants,the seperation between nodes will be much greater than if the ends of the grow were always within the usefull light range of the hood,this isnt word of mouth info, its info from a light mover user/owner who's tried exactly whats being proposed in this thread & failed miserably,this has nothing to do with my grow skills either,ive posted many pics on this site showing my gardens & im well aware of how to run a healthy garden.

My movers in action.



A 400 watt light is just too small to make a 4ft run successfully without adding to plant stretch,if you can find or modify an existing mover to run within a 2ft range thats perfect for a 400 watt light but a 4ft run is too far a run.What light movers are good for is to get maximum light to all areas of the grow,not to take the light outside its effective light throw range.

OregonMeds said:

You have to keep all your plants at identically the same level and practically drag the top of them with the light down just low enough not to burn while it's moving.

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This is how i run my movers but i have vented hoods.

If you do this with an unvented standard light hood you will end up with scorched buds,light height needs to be measured by canopy temp directly under the light while its making its run, not inches.

it dont take 20 min to get light the hood is around 2 1/2 ft so when its moving across its not 1/3 the time the lights on the plants its more like 1/6 because your not looking at how big the hood and reflector is....

i think that light movers are perfect for certain styles of grows....im gonna be doin an aero grow and i think a light mover will be perfect for my style of grow whick will be a SOG......

plus i dont have a vented hood not much heat will build up with a moving hood but i also got isolating fans moving the heat away....

good decussion though lets keep it goin

cali-high said:

it dont take 20 min to get light the hood is around 2 1/2 ft so when its moving across its not 1/3 the time the lights on the plants its more like 1/6 because your not looking at how big the hood and reflector is....
i think that light movers are perfect for certain styles of grows....im gonna be doin an aero grow and i think a light mover will be perfect for my style of grow whick will be a SOG......

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Grow style is irrelevant,plants need a minimum of light no matter the style.

I have timed all my movers rotation cycle's as well as all my lights tempature ranges & recorded the info so if my rooms ever need to be broke down completely i have reference data to set them back up quickly.

Here are some quick facts.

In a room that is climate controled to stay at a constant 75 degrees with 55% humidity durring lights on a non vented 400 watt hps with an eye hortilux bulb generates a temp of 114 degrees at 2 inches from the bulb,this is with a 20 inch fan blowing directly on the light from 5ft away.

You have the heat issue covered with your vented hood but the op may not have a vented hood,he never specified,if his light drags the canopy at 2 inches he will roast his plants with 114 degree heat,light height needs to be determined by the temp directly under the light right on the canopy,not by inches.

You are correct that a 4ft mover dont take 20 minutes to cycle,i double checked this figure from my files,it takes a 4ft hydrofarm light mover exactly 24 minutes to make one "Complete" rotation,that means when the mover is making its cycle the plants on the far ends of the grow will need to wait 24 minutes before they are recieving max lumens again,max lumen output is at dead center of the light,when the mover starts moving the light away from the outer plants lumen output fades very quickly,once the center of the bulb is more than 18 to 20 inches away from the plants on the outer edges of the grow they are now out of the effective range of the light.


With a 400 watt light the effective range is 18 to 20 inches on both sides of the bulb,not 18 to 20 inches past the reflector,when you push past this range the light looses effectiveness,this leaves the outer plants well outside the effective range of the light throw & bud weight will suffer & stretching will start,every minute a plant is outside the effective light throw range the plant wants to stretch to meet the light,its a natural instinct that can only be prevented by supplying the plant the light it needs to be happy in its current position to the light,if it is not getting enough light it will focus its energy on stretching to meet the light instead of bud production.

thank you, for the advice,

I do not have a vented reflector just standard batwings, but I have not seen any stretching of the plants with an exception of 2-3 colas that maybe stretched 2" higher than the rest, but after 4 weeks my plants are no higher than 8" above the screen