How much light is too much?

[danoz]

Hi all

 

I'm currently on my 3rd weed grow but i have grown other plants hydroponically plenty of times.

 

However this particular grow is giving me a little grief i think i am doing all the same things as usual but my plants look a little stressed and the growth rates are poor. The grow system and room are new and there are a few questions i would like some feed back on.

 

The watering system is a recirculating one i made myself because my commercial grow table wouldnt fit in this place.

See pic

 

 

The water gets back to the main tub (black tub with fan on top to the right of image) via gravity.

 

I suspect my plants are stressed for one or combination of a few reasons

1 - Too much light its only a walk in closet and i have 2 X 600w HPS room is 1.2 x 1.3m

2 - Insufficient dissolved oxygen.

 

1 - I realise that according the to light calculator supplied on this site my room has way over the optimum light level however reading posts on this site seem to contradict this as people have reported using over this amount of light. Furthermore some have reported better and tighter buds with this light. (i have no CO2 supplement)

- has anyone had trouble with this amount of light before

- has anyone tried the foliar sprays that are ment to enhance photosynthesis in high light conditions?

- i seem to think that i need co2 for this amount of light ne thoughts?

 

2 - with the system i made. the water has little contact to open air and i do not have a nutrient tank aerator i realise this could be the problem especially seen as the systems pump is never off however i have always grown like this but it wasnt a prob in other systems had great growth and yields.

 

Nuts range from 1.8 - 2.2 ec

Temp always between 20-30 degress c

pH always between 6.5- 5

humidity not sure i just keep the ventilation flow high

 

poor quality pics i know but u can make out the intervienal chlrosis and the wilting

 

any help would be muchly appreciated.

[nouseforaname]

hey,

Probably is a bit of an overkill on the lights at such a young stage but they dont seam to mind it.. To me it looks like overwatering on the right front plant in either tray and possibly gettin to hot or arid in there.. to add oxygen to resy just have the return hose above the water level.. A old grower once told me you can only be as good as your worst imput overall which is a good thing to think about.. Theres not much use throwin that much light at them when other important additives are lacking.. Have flowered with 1200 watts in same area with no co2 but was in aircooled hoods to handle temps... Hope that helps some

[danoz]

that helps alot thanks heaps

i have thought long and hard and done some research and i agree i think its over watering it is unknown genetics to possibly this variety is more susceptable to water logging that others i have grown.

i have had the return nuts dribble into the res to aerate the tank before but with this system i can they are all joined at the bottom. so i think ill buy an aerator to eleminate this possibility afterall they only cost $20

 

when u flowered in a simular space with 1200 watts how did they go ?

Edited June 28, 2008 by danoz

[nouseforaname]

hey,

No probs glad could help out.. For unknown genetics they still look pretty nice.. Well everyone has a different take on this but to me you should finish with maximum wattage possible.. work from the finish back to the start.

 

My take on it... Your room is 4x4 feet so 16ft2 your up near 80 watts a square foot but your grow area is only really 8ft2 .. plants would grow on 5-20 watts a foot , start 4 weeks of flower on 40 watts and final 4 weeks flower 80 watts a foot. You will be surprised by the results it works better than throwin everything you have to start... but just my 2 cents at a guess u should be in the half gram a watt range for yield..

 

Few qs.. whats stabbed into the rockwool in the pic (looks like a tester or a knife??) and whats the watering cycle set at

 

You could T off the feed line just above the pump and add a small return line to splash back into res as it runs to aerate aswell

[danoz]

i like your logic straight after this i will put the lights on timers and make them take it in turns one light at a time per light period.

[nouseforaname]

hey,

dont think it would be of much use.. Have you worked out the light footprint from your shades at all. One light should be plenty if set right way..

[danoz]

i havnt worked out the light foot print.

im avoiding having to reposition the light and take one down so ill just run it this way the plants not directly under the running light still get plenty especially seen as the walls are all covered in white plastic from hydro shop

[biggerbuds]

no HID lamp can match the power of the sun,so i do not think you could ever give to much light,clones are a different thing though.

[bufo marinus]

Yeah, that light is fine.

Overwatering

Nouse has the lights per w per foot thing worked out, especially the clone to veg to flower idea... if only I could too

[Radic]

irey buds and bufo

i with you on this 1

seen

too much light is impossible

they will take all you can afford to turn on

it is just a q of economics

$/m2 = %increase yeild

but there is a point of noreturn for the extra $ invested

so it depends pon how much the electric bills are as to how much increase you get in your yield

it is a very good Q really

it is very complex course to nevagate

cause different stages of growth bennifett from different combos and intencidies of light

and every strain is different too

electrisity costs $/watt can fluctuate too

the best way to find the answer is to keep accurate records

trial and error streemlining each grow form preivous refferances

it just keep getting more complex

 

yo nouse

you could be right too

at this stage in growth less watts may produce the same growth rates

so why waist $$$$$$

seen

irey danzo your so right

they are not happy in there

and a combo of problems is usally the cause

seen

imo

30c is way too hot

max at about 25 works better for me

so i'd do whatever it takes to achieve dat

next i'd

flush and start again witha fresh nuiternt soluition

at half strenght for the first day after the flush

then next day

back to full strength and follow the plan as directed

 

irey guidance