Seedling leaves are curling down..

[Rush56]

Hello everyone,
I'm new to this forum.
Well this is my first full indoor grow(Full becouse last year bad weather and incoming winter wouldn't allow my plants to finish flowering and it had few weeks left so i had to put them in and thankfully i got great yield.)

So the problem is... I have 4 plants, 2 bubblegummers from female seeds and 2 grapefruits also from female seeds.
The 2 bubblegummers have much bigger leaves and at both plants(bubble gummers only) the biggest leaves are curling down, also on one of those 2 plants i noticed on that curled big leaves(2 leaves) some brown spots, hard to see..But they are there..??

My seedlings are 2-3weeks old, temperatures were until now about 25-27.5 degrees celsius and today i added another fan so it droped to about 23 at top of seedlings(Also lifted light a bit to see if that is problem).And 17-19 dgr celsius in night cycle. Light is 400w MH and is 30-40cm away from plants. I also have one 30W CFL per plant as additional light. I don't know the ph, currently i'm low on money to buy a meter..Also i don't know humidity but i doubt that would be problem..
I was reading that it is usually overwatering, well i did try with my fingers about 1cm or more under top of soil to see if it's dry before watering, but i had to water on 2 days as i put light closer and fans were drying out the soil, but non of fans is blowing directly on plants(I also try with hand and feel no air moving, just a little above plants there is). About ventilation, i have 2 oscilating fans blowing above top of seedling towards MH and 2 computer fans(120mm) which i mounted directly on MH light reflector, blowing in same direction as oscilating fans. I also have one smaller but pretty strong computer fan for intake and 2 for exaust(1 is at bottom of room so it doesn't do much, i know i should have bigger intake then exaust, but there is enough holes in/around door to get air in).

Another question is about grapefruit sativa..After i bought it i realised that it is sativa and supposed to be only 50-60cm high.. Well what is my plan from those 4 plants and why only 4 plants is becouse i want to LST them and get bushy, big plants with many buds.. Do you guys think i can still force that sativa to be bushy and big?

I hope you guys can help me with that, i don't want my plants die after very hard work to get room as good as i could for low budget :-)

P.S I have them on 18/6..

 

[Shredder]

Your right to suspect over watering, what do you use for soil aeration? Perlite, vermiculite? Soil type? Water schedule? Are you letting them dry out before watering?

Never grew the grapefruit, but most plants take a fair amount of abuse as long as they are otherwise healthy.......good luck.......shredder

 

[Rush56]

I only used the soil that i bought for seedlings, i will transplant to bigger pots in about one week now.. I didn't add anything for aeration becouse it was just starting soil, then i have prepared some mix ( Plagron Royalty mix).

I water when lights turn on or before they turn on as i have to leave for work earlier, but i didn't know its best to water when lights turn on so until recently i was watering at night cycle..

And yes, i am leting them dry out before watering but maybe they didn't dry out enough, but pots are light and i try with my finger to go in soil to see if its dry down under surface..

 

[Rush56]

Ok things got worse now..the two grapefruits which were ok yesterday the second set of leaves from top down changed color to little lighter green, maybe some brown too.. it looks strange, didn't have that never before..
I was also checking online for pictures of 2-3 weeks old seedlings and mine seems just lot too small..I also noticed that the roots already got to holes of small pots..Would that be the problem? I was also foolish and when plants were born i added some lime, i know the soil is supposed to be 5.5-6.5, and i didn't even test ..:mad0233: ..well it was small dosage..i don't know why i did it..
Should i transplant immediately?

thanks..

 

[Cloudy in here]

I found a male plNt in my room and removed it and I stopped watdring it to see how long it will live, well its been seven days in a red beer cup and its still strong..they really are happier with less water AND less nutes