Where is the problem?

So basically it is my 4th grow and i get really small yeilds aprox 10/15gr per plant
I'm using seeds from World of seeds,before i had skunk 47,(http://worldofseeds.eu/eng/wos_bank_26.php)and now im growing space (http://worldofseeds.eu/eng/wos_bank_29.php)
My grow room surface is 1.5m3
I've 2x2l bootles producing co2 from sugar/yeast
im using 600w hps (sylvania) bulb is 4months old
reflecting materials only plastic foil for sandwiches
I've got 12in fan and ionizator/water humidifaier (or however it is supposed to by spelled )
pots are 10-12l and there is 6 of them.I'm watering them once evry 5-6days
No matter what kind of photoperiod i use,i still get small amounts.The biggest that i got was with 140g from one plant growed for 26weeks 20/4.... soo i feel really sad.
I've trained them with lst and fim
The nutrients that i have are:
BIOBIZZ:
-ROOT JUICE 01-01-01
-fisH MIX 6-2-4
-BIO BLOOM 2-6-3.5
-TOP MAX
-BIO HEAVEN
ADVANCED NUTRIENTS:
-IGUANA JUICE GROW 3-1-3
-IGUANA JUICE BLOOM 4-3-6
-SENSI ZYM
-HAMMER HEAD PK 9/18
-REVIVE
-WET BETTY PENETRATOR AGENT 0-0-1 BOTH OF THEM
-B-52 - 2-1-4
-PIRANHA POWDER
-TARANTULA POWDER
-CARBO LOAD
-BLOOM BOOSTER PRO 0-48-27
-NO MERCY C02 TABS
-BAT GUANO 3-10-2
-CANNA BOOST
-CANNA PK 13/14
-GHE RIPPEN
Of course im not using them all I keep ph between 6,5-7,5,and here you have some pics:
The "very big bud..."

4th week of flowering

Plants have aprox 20cm heigt (only one week of veg in this grow) and i keep the light aprox 35-40cm above the plants,so they dont get burned

And the buds grow seperately,i mean there is no one huge top,only coupkle of small ones :/
Any ideas?

I dunno, seems like you're doing too much.

KISS

Just give it what it needs. Veg or flower fert. Decent grow medium. Enough light for space/amount of growth. Water when the soil is dry and the pot is light- i.e. MORE often as the plant/roots get bigger.

IMO you're doing too much, adding too much, it's impossible to know what's hanging you up. Start at square 1 and then build off that, one thing at a time. If it works keep it.

Longer Veg = more yeild

If you veg 5 weeks in larger pots I bet you could double your yield.

well one of the things i noticed is your plants. everyone seems to be different. like each one comes from an entire different line. genetics maybe? or are they all actually different strains?

just checked out the site for the seeds. man are they expensive.

okay, one more question, sorry for the edits. do you have any pics of your previous buds? maybe you are harvesting too early? the last 2 weeks of growth is where they put the weight on.

No matter what photoperiod????? 20/4????? do you mean 20 hours on and 4 hours off for flowering???? if so then thats your problem. 12/12 for flowering....NOTHING ELSE!!!!

i dont think he has a lighting time problem, the buds are forming and not all stretched and funny like they would be with lght problems.

even going 12/12 from seed, you would be harvesting 1 to 1 1/2 oz. per plant under 600 watts

chuckb
I said im not using all of them,for veg ml/1
first 1.5-2 week nothing
then next 2 weeks root juice 5ml and after:
5ml iguana juice
2ml bio heaven
4,5ml sensizym
2ml wet betty
2.5ml b52
pirahna + tarantula according to the directions
no mercy 2 tabs per pot.
another 2plants grown with bat guano instead of iguana,but the same result.All dates on nuts are fine.
For bloom:
5ml iguana bloom
4ml sensizym
2ml wet betty
2ml b52
in mean time canna boost+pk 2.5ml
carbo load + bloom booster according to directions
last 2 weeks rippen goes twice 5ml
and then one week on water only so leaves can go yellow.

jeff f
All of them are the same,the other 3 plants visible on the 3rd pic are in veg,the thing is that im saving energy,and use only one bulb for flowering,.and then move them to the another closet for next 6h of light.
btw. previous buds were really brown,i mean they were ready for 110%,besides i used the microscope to look at it,and it had proper colour,so i dunno whats wrong:/

whiteboi4202
I mean 20/4 for veg,and then 12/12

jonboy30
exactly,thats why i ve the problem