Can HPS lights make plants appear to be yellow?

im having a hard time being able to tell if my new leaves on my plants are yellow or if my hps is making them appear yellow. when i take pics w my digital camera they dnt really look as yellow. i was thinking it might be the hps making the new growth look yellow since its thinner or something idk.

also can anyone tell me y the leaf edges are curling up? it cant be heat stress cuz the temp is in the mid 60s F. and i dont think it salt buildup cuz i only use ro water and i had this problem before i even started adding nutes. and idk how it would be over/ underwatering cuz ive tried watering 3 times a day all the way up to 24 hrs a day (top feed drip).

Turn ur hps off, and then get a normal daylight bulb in a lamp for something and see what color they are.

They will mae them look yellowER. But if they look yellow at all, thats too much yellow unless its in its last week imo

The new growth is GONNA be a lighter green, even almost yellow, and the spectrum of HPS is going to accentuate that.

Just take them out of the box and look at them? lol

If you don't mind spending a couple of bucks....

Look at a glass blowing supply company and get some didymium glasses:

http://www.waleapparatus.com/index.asp?category=25401 (you can find cheaper/economy style ones for like 15 on eBay)

They are made to filter out SODIUM FLARE so glass blowers can see what they are working with, and not burn their eye balls. I have a pair, and they are wonderful for cutting the yellow out of the light. I not only use mine for more pleasant and accurate viewing, but I also take pics through the lens and I can get very vivid color under the HPS.

EDIT: Here is a link to a pic I took through the filtered lenses - http://anteletech.com/images/100_3371.JPG

apbx720 said:

also can anyone tell me y the leaf edges are curling up? it cant be heat stress cuz the temp is in the mid 60s F. and i dont think it salt buildup cuz i only use ro water and i had this problem before i even started adding nutes. and idk how it would be over/ underwatering cuz ive tried watering 3 times a day all the way up to 24 hrs a day (top feed drip).

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Dude, IMHO, your plants look healthy enough to not freak too much. It would be a good idea to reach for 75ish for your temp, but they look to be in a general state of good health. From my very limited, but varied experience, looking too critically at each and every last little wrinkle on a plant will not only drive you batshit, but make you love your plants to death.

Bravo, CaptainNoob!!!! You got it! +rep for you.

apbx720 said:

im having a hard time being able to tell if my new leaves on my plants are yellow or if my hps is making them appear yellow. when i take pics w my digital camera they dnt really look as yellow. i was thinking it might be the hps making the new growth look yellow since its thinner or something idk.

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High-Pressure Sodium (HPS) lights

High-pressure sodium lights yield yellow lighting (2200 K) and have a very poor color rendering index of 22. They are used for the second (or reproductive) phase of the growth. If high-pressure sodium lights are used for the vegetative phase, plants will usually grow slightly more quickly. The major drawback to growing under high-pressure sodium alone is that the plants tend to be taller and leggier, with a longer internodal length than plants grown under metal halide bulbs. High-pressure sodium lights enhance the fruiting and flowering process in plants. Plants use the orange/red spectrum HPS in their reproductive processes, which produces larger harvests of higher quality herbs, vegetables, fruits or flowers. Sometimes the plants grown under these lights do not appear healthy due to the poor color rendering of high-pressure sodium, which makes the plants look pale, washed out or nitrogen starved.
High-pressure sodium lights have a long usable bulb life and six times more light output per watt of energy consumed than a standard incandescent grow light. Due to their high efficiency and the fact that plants grown in greenhouses get all the blue light they need naturally, these lights are the preferred supplemental greenhouse lights. But, in the higher latitudes, there are periods of the year where sunlight is scarce, and additional sources of light are indicated for proper growth. HPS lights may cause distinctive infrared and optical signatures, which can attract insects or other species of pests; these may in turn threaten the plants being grown. High-pressure sodium lights emit a lot of heat, which can cause leggier growth, although this can be controlled by using special air-cooled bulb reflectors or enclosures.

Hope this helps: http://en.wikipedia.org/wiki/Grow_light

CaptainNoob said:

Dude, IMHO, your plants look healthy enough to not freak too much. It would be a good idea to reach for 75ish for your temp, but they look to be in a general state of good health. From my very limited, but varied experience, looking too critically at each and every last little wrinkle on a plant will not only drive you batshit, but make you love your plants to death.

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yr right bro i do need to chill i know. its just a little sketchy sometimes cuz ive had plants go to shit really fast and i try to stop a prob at the beginning before it gets bad. as for the temp, ive found 60s to make them happier. i think maybe its because im running a 1000w hps in a small area, and that fucker puts out a lot of heat, and i think somehow that heat is getting to the plants even tho room temp is 60s. the thermometer right below the light reads 80 so...

ok so check it out. this plant is a clone which is in soil instead of hydro like the other pics. the soil is as healthy and beautiful as can be. god damn i love that lil plant. anyways so i put that plant in w the hydro just to compare color under the hps. the soil one is much greener under the hps than the others. also new growth on the hydro is much skinnier leading me to think i might have burnt them. i upped nutes last week from 650ppm to 720ppm. do yall think they might be a lil burnt? thx for everyones help i really appreciate it

The one in the soil isn't producing plant matter nearly as fast, I'm guessing.... As a result, I am thinking it is safe to assume the color difference is due to the soil plant having a proportionally higher concentration of chlorophyll per sq/in of leaf since it isn't growing out as fast and getting spread more thin, if that made any sense.

Mind you, I am only rationalizing the comparison. I have noticed that my smaller/slower plants are usually darker, and I always just assumed this to be why.

ya yr right the soil one is 8", the hydro that started at the same height are now 11.5". they ones directly under the light are especially yellow. what would cause this? is it that the amount of N cant keep up w chlorophyll production? another thing everytime i check the ppm it is lower. dropping about 40ppm per day. is this a good or bad thing?

apbx720 said:

ya yr right the soil one is 8", the hydro that started at the same height are now 11.5". they ones directly under the light are especially yellow. what would cause this? is it that the amount of N cant keep up w chlorophyll production? another thing everytime i check the ppm it is lower. dropping about 40ppm per day. is this a good or bad thing?

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It's a good thing... It means your plants have a hearty appetite.

The ones directly under the light are growing faster, so they are probably producing chlorophyll slower than plant matter even more so than the rest. I am GUESSING you could afford to increase your nute concentration... I would bump a little, or add an additive and see if they handle it well.

your plants look awesome looking at one of the pics i notice slight browning on the tips not sure if its a start of a burn either way they look nice

DrFever said:

your plants look awesome looking at one of the pics i notice slight browning on the tips not sure if its a start of a burn either way they look nice

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thx drfever.just tryin to keep em happy

its all good it appears the one in hydro might have a csase of burn coming as u noticed and posted in above post get her corrected ease in on the nutes good luck

DrFever said:

its all good it appears the one in hydro might have a csase of burn coming as u noticed and posted in above post get her corrected ease in on the nutes good luck

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thats what i thought too. the yellowing has gotten worse since i posted, and also when compared to the soil the hydros new leaves are a lot skinnier than the soil. i bumped nutes from 650ppm to 720ppm 2 days ago. the skinny leaves especially lead me to believe they might be burn. so about 2 hrs ago i added ro water til the ppm was 400. how long should i leave em at 400ppm?