Distance From Lights?

[melver]

Hi,

 

I have just installed a 250W hps in my cupboard grow room. I have very little height to work with, my babies are about 3 foot away from lights. They are showing signs of leaf burn and are curling downwards which I know is a sign of overfeeding so I have washed the grodan blocks through and started using a 10% nutrient solution rather than 1/4.

 

I have not given them enough time to see whether or not is overfeeding but just to cover all angles I was hoping for some advice on the distance of the light both at this stage and later on in the growth phase.

 

They had developed a white mould and I was using a solution of H2O2 and bicarb of soda up until a couple of days ago.

 

Thanks for any help or advice

 

Melver

[white_cluster]

what on earth does bi-carb do?? I never did no school but i had the idea it would raise your pH crazy amounts, because it reacts with vinegar and acids and alkalines react together dont they?? anyway I dunno what I'm talking about there, but stop adding bi carb to your water, lower your light to about a foot off the ladies (lower it a foot a day to get them used to it).

 

rockwool usually develops mould on top in my experience, and its no real problem as it is just on top it'll go green and stink like shit without causing any problems, but keep using that peroxide to keep root diesease under control, and check your waters pH and keep it around 6. that sounds to me like the problem a pH problem.

 

how old are your plants??? any plant with a couple of leaf sets should handle 1/4 strength nutrients.

[melver]

I did not know that about rockwool, thanks.

 

The bicarb was recommended to kill the mould that was growing on the blocks and a couple of the leaves, supoosedly raising the pH kills the mould.

 

The plants are 3 weeks old with seven sets of leaves. My pH of my nutrient solution is always around 6, formulex, some superthrive and a little H2O2 every now and again.

 

I am very worried about the heat from my new light, the room remp is maintained at around 30 it but gets much hotter closer to the light.

[Guest Wilderbud]

Are you sure its not high humidity causing the problems?

[Luke Skywalker]

Sounds like you've got no venting in there.... Do you?

[Wezz]

yep..definetly put a fan in the room..

[OldmanMozz]

put hand, palm down, under light (at canopy level) for couple mins. if its to hot for your hand its to hot for your babies.

 

 

 

cheers an cones Mozz

[Guest Wilderbud]

In this heat you need to recycle the air not just recirculate it.

[melver]

Thanks for all the replies,

 

I do have fan, should have mentioned it earlier, blowing from the outside in. Not all of my girls are showing this burning, 4 out of 5 is close but one has no effects.

 

I have lost my humidity measure, another should be arriving shortly, but I did I did not know high humidity causes burnt spots on the leaves??

 

I can hold my hand under the light near the canopy for awhile and the temperature at canopy level is 29 degrees C.

[white_cluster]

put your fan on as exhaust and drill some holes in the other side as intakes. best to have exhaust at the top of your crop and intakes at plant level.