This is my first grow. Not sure why my babies are ...

Pretty much what others have said. Either pH is off, or way too many nutrients, or maybe even root-bound (I've experienced this with all kinds of plants and they can give an assortment of weird reactions). I don't expect you to pick my answer because I'm just repeating what others have said, not trying to come in and gank it out from under them... Check my diaries, I just started growing cannabis. I tinkered with growing it for a brief time in my teenage years but I'm basically back to being a noob again. Maybe you can find something in them to help you, as I've made lots of verbose notes! :P

stop biogrow for sometime and reintroduce at 0.25ml/l, at most 0.5ml/l... its too strong. i always start low and go max 1ml/l... and I think they are not getting enough light.. how high is your light and what light is it? hope I could help. happy growing! =) Tchau, do Brazil.

If this was me I think what I would do is feed em some low dosage of florakleen befor transplanting them into 5 gallon pots (air pots > fibre pots > others) if you transplant into good soil you’ll pick up the nutrients from new soil buying you a window to buy yourself a 3 part nutrients system. If it’s not a money thing ..... I’d be looking at air pots filled with coco coir and feeding them Green Planet 3 part plus. GP3 has a 7 bottle trail pack for pretty cheap.

The color of the stem would suggest a ph issue. Locking out the nutes leading to the lime green color. As for the dieing leaves at the bottom, they are they first set of "true leaves" witch will die. Dont panic. Check your ph and bump up your nutes. Also by the way they are streching, the light is to far away

Not sure what is in those nutrients even after having looked them up. Also seems like those nutes are part of a bigger line of nutes. Maybe that's part of the issue? One of the nutes listed in the nute schedule is a fish-based nutrient which is likely where most of the nitrogen in that line comes from. Without enough nitrogen, you will have slow growth and the lower leaves will yellow and die off. New growth looks good so the pants aren't in dire straights, they are just hungry. Maybe go out and grab the rest of the nutes for that nute schedule? If you cant do that at least get some nutrient with more nitrogen in it. Also with how small those guys are for week 5, I wouldn't use week 5 of the nute schedule if you are. Those guys look much closer to around week 2-3 of a normal healthy plant. If you want to try a different nute line even, I can definitely recommend Megacrop. It is what I use, it is simple and cheap. It is a 1 part nute that has everything the plants need from seed to harvest. As the plants get bigger you just increase the dose of Megacrop.

they are not dying you need yo add nitrogen to your water they need a boost thats all some seaweed extract also would help

I'm going to give you a shorter answer that is related to the above answers... You are giving the wrong nutrients at the wrong time. They need a boost of nitrogen like biogrow, you will immediately see improvements if you feed them correctly, your light is too low and temperatures are too high. The pots are very small too, need to double the pot size but not until you've fed them and they've recovered! You can fix this if you act quick!

No they are not burning or dying but they are suffering from a lack of nutrients. They are pale green and the lower leaves have burning edges ( I know I just said it wasn't a burn , but it's not really a burn , more like a drying 🙄 ) Bio heaven and top max are not providing the basics nutrients as they are both additive and should be used alongside with Bio Grow during the vegetative stage and Bio Bloom during the flowering except if your soil is a super soil , in that case the additives are enough. In your case it could be a N or Mg def. Feed correctly and they will do better but the affected leaves won't recover