Plants growing too slowly... Help please!

Hi. I'm new to growing indoors however I have extensively researched many a aspects of growing.

My current set up is a built in closet, it has 1ft of depth 2ft of width and about 5ft of height all lined in mylar with a pc fan in the bottom right exhausting from the room creating a small negative pressure. I have 2 CFL bulbs 135w each at 5500K which were around 1&1/2ft away but now only 4" from the tops. The plants sit in 7L pots with Canna seedling mix, the oldest being the Pineapple Chunk @ 50 days from seed and the Big Bang @ 43 days from seed and only gaining 5" in height for the pineapple and pushing 3" for the Big Bang.

They're fed bottled distilled water 500ml per feeding adding Hygrozyme @ 4ml per liter and now I've just added Iguana Juice @ 1/4 strength due to a mishap. On day 30 I fed the Pineapple 500ml of the same nutrient feed as I have just done today and the Big Bang a little lighter due to being 1 week younger and the leaves drooped right down feeling very soft with slight yellowing, now they are recovering (I Think) but I have stuck with just hygrozyme and distilled water since that one feed up until now.. the leaves that suffered some browning and yellowing have stayed the same getting slightly greener but not much. The new growth is green and lush, I have topped the Pinepapple and it looks great however there are still yellow/green leaves and the 2 half green half brown ones but new growth is lush and green. The Big Bang ain't very big at all... just over 3" in 43 days from seed is almost backwards to me.. there is new growth but it's rather tiny! still very green but it also suffered a couple leaves turning brown, my thoughts were over watering but possibly nute burn too early given that the germination time totaled about 14 days til sprout.

I Intend on buying a 250w HPS and cooltube with a digital ballast along with a fan and carbon filter kit but before I invest how would the 250w cope in a space of this size? heat issues or intensity of light? If so I can extend the wardrobe to the right by 1ft removing some shelving increasing the width but not depth.. I'm hopeful that this extra 1sq foot will help otherwise I will settle for 150w but ideally 250w is my goal for now. I have a homemade SCRog net built in but the Pineapple is the Indica Pheno and very squat so whether it'll reach the net i don't know.. I'm also hopeful that the Big Bang will shoot off with some food very soon but 43 and 50 days minus 14 days until sprout is still rather long, why would the get stunted?

Great forum and I hope you guys can help me

What are your temps like? The Barneys Pineapple Chunk is very fussy to grow, it gave me a ton of trouble too.

I would think exhaust. Fresh air for c o2 is important and what Bout your intake? Negative pressure is only needed for carbon scrubbing. Without it no need. Work on air flow and I bet u get results. Not sure how strains differ as im doing northern lights for my first real grow other than the multiple bag seeds.

Sounds like you just haven't reached rapid growth point yet. It'll happen just be patient. Don't overlove your baby girl

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Although with the time they've been alive it is pretty slow growth. I don't know anything about the strain.

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Thanks for your help and support guys, much appreciated! My temps are around 20C on occasions i've seen around 22C but nothing higher than this so far. I am hoping to take on a proper fan and filter kit but for veg i'm not too fussed as long as the PC fan can replace most of the air, My intake points are slats within the door its self, they are approx 2mm thick gaps and 1ft in length with a total of 48 slats pulling air in... if i'm correct the fan pulls out half the amount of air that is able to come through these gaps in the door, as for light leakage it is pretty minimal only where the doors meet is there any visible light. I understand the rapid stage of growth but my thinking is i stunted them rather early and since they've been recovering i've lost a few weeks of growth where i could have started a scheduled feed a bit earlier.
I have some pics i'll up load shortly and I will take some of the set up so you guys have as much info as I do on this, thanks again bro's!

The first 4 pics are the Pineapple Chunk Pheno No.4 Indica Dom, and the last two are the Big Bang seedlings.. both are fem too.