Why is my plant growing slow?

ao here I have my jack herrer and she is just really growing slow she started off great looked healthy strong tap root, but I'd say about 3 weeks in she started yellowing on the tips of the leafed and then next thing you know the bottom leaves were almost completely dead so I cut them as you can see in the picture. I gave her a feeding of flora nova grow and some cali magic assuming she was just hungry nd needed food but it's been about a week and still not really a change at all. So can someone please help me out here.. I can't think of what's wrong with her.. other then there's some gnats in my grow box I was thinking maybe larvae in the soil? Any tips would help a lot... and yea I will handle the gnats with some neem oil and some hydrogen peroxide for the larvae

carry on, you'll be fine. bigger pot, better light, consistent temp..... enjoy

Try adjusting your waters ph level, looks as if it's some serious nute burn

Need more info. How much do you feed? What soil are you using? What pH do you use for your water?

I feed them half teaspoon of flora nova and and half teaspoon of cal mag in a gallon of water end i ph my water at 6.5

theres no way you got nute burn if your only feeding 2.5 mls/gallon
unless that's some extremely hot soil you potted

the potting soil.. is it hot (already has nutes) or is it for seeds?

i think you got nute deficincy

feed 4ml/ gallon working your way up to 6ml/gallon over the next 2 weeks

the cal/mag dose is good

also..do you have small white freckles or pimples on your plants?? could be spider mites

also
don't use hydrogen peroxide in your soil

get gnatrol and azamax and silica foliar for your gnats