Leaf curling on some of my seedlings?

[ChestrCopperpot]

This is my first hydro grow and I am getting this noticeable leaf curling on a few of the seedlings. Is this a deficiency of some sort? Too dry? Any help will be greatly appreciated.

Info (HYDROPONICS):

What STRAIN are you growing? Speed Queen
What was the establishing technique? (Were the seed or clone?) Seed
What is the age of your plants? approx 20 days
What PHASE are the plants in? (seedling, vegetative or flower) are the plants in? Seedling
What Technique are you using? ebb/flow table
What substrate/medium are you using?(Hydroton, RockWool etc.) Hydroton
What is the Water temperature? not sure...guessing around 70F
What Nutrient's are you using? How much of each if using multiple? Botanicare pure blend pro veg mix
What is the TDS/EC/PPM you are using? half strength - 440ppm
What is the pH of the "Tank"? 5.7
Are you sure your calibration is correct on your equiptment? yes
When was your last watering?6 hours ago
When was your last feeding change? (ie. grow-bloom-micro-additional)4 days ago
What size bulb are you using? 400w MH
What is the distance to the canopy?approx 3'
What is your RH Factor? not sure
What is the canopy temperature? 79F
What is the Day/Night Temp? (Include flucutaion range)fluctuates between 74-81F
What is the current Air Flow? (cfm etc.) 150 cfm exhaust..passive intake...
Is the fan blowing directly at plants? no[/b[
Is your water HARD or SOFT?slightly hard - 7.5 out of the tap
Has plant been recently pruned, cloned off of or pinched no
Have any pest chemicals been used? If so, What and When? no
Are plant's infected with pest's no

 

[MynameStitch]

How long do you have it misting and how long between the next?

To me that looks like it's heat issues..... 3 feet for 400 watt mh for seedlings that small is toasting them. your pH and nutrients are fine and PPMs is not high..... raise the light up a bit..

what is your RH? Need to know; if you have low RH that can also cause curling of the leaves upwards.

 

[TahoeTops]

Looks like heat stress to me as well. RAISE the light! Somethig that small should have flourescents on it.

 

[MynameStitch]

I agree with Tahoe; around the size and age of this plant they love to stretch when light is not close enough; using high wattage MH on those seedlings is a waste; I would use fluros or compact fluros until they get a bit bigger then hit them with the MH, I would wait till they got at least 4 sets of leaves before switching over.

 

[ChestrCopperpot]

Thanks guys...I will try to move the light up. I agree it's a waste of energy but I am semi-commited to this light source for the current grow. On my next go-around I will definitely have a fluoro setup for the seedlings.

RH is measuring humidity correct? That could also be the problem because I live in an extremely dry desert climate.

 

[MynameStitch]

Get a humidifier in there and get a timer for it to come on at random times; you want it to be around 45 to 50% for them seedlings.

 

[TahoeTops]

When you say you are comitted to this light source, I am asking why??? Why can't you go to your local hardware store buy a 4 foot flourescent fixture and set it up just above the plants. You can get one for under $20 and set it on two boxes on either side. You would be much better off.

 

[ChestrCopperpot]

When you say you are comitted to this light source, I am asking why??? Why can't you go to your local hardware store buy a 4 foot flourescent fixture and set it up just above the plants. You can get one for under $20 and set it on two boxes on either side. You would be much better off.

I didn't say "committed," I said "semi-committed" and that is purely in the sense that I dropped a decent chunk of money on the digital MH ballast and from what i've read MH is superior for vegetative growth anyway. Being over 20 days into this grow it doesn't make sense to me to go out and re-configure the whole closet for a flouro setup at this time. Either way, I want to use it for the next grow so I see your point. I am going to try the humidifier first to see if it has any improvement. I am not sure the light is too close since I can hold my hand underneath where the seedlings are and it's not uncomfortable in the least...one step at a time however. Thanks for the feedback guys.