really need help people with my seedlings

o.k. so i have a 250 mh light roughly 2 feet away from pots. they were under a hps and were growing nicely but then i changed light to mh about 2 weeks into grow. they have not grown much since the change and 1 strain has developed brown crispy leaved. the ph is just above 7 and i am using pre mived soil with little nutrients so i dont think they are a factor. i have 4 diff strains in my room and they all seem to growing slowly. i am watering them only when needed.

Could be the soil,looks really wet. Be sure to let the soil dry out before you water if it's dry about two inches down time to water. Or maybe the need a good flushing. Hoped I helped

MH is supposed to be better for vegetative but if it turned your plant brown and crispy either raise it up a bit or switch back to the HPS and see if she does better, maybe?

I would switch the bulb back until you are ready to flower them. Water them only when needed. Stick your finger down in to feel the moisture level. If you are already using nutes, keep em light like 1/4 strength. Also keep the light as close as you can with out feeling to hot on the tops.

do you think its normal for a plant to be this size when 25 days from germinating?

no with your type of light no it should be way bigger.first off i dont think its being burned by the light cause the other parts are still moist looking and if they were burning then they would be crispy looking.Im not sure of over water cause you could of taken that picture after you waterd recently but it maybe its possible the lights to far away from the plants, did you put your hand under neath to find the closet possible point the light could be from them? as far as i know hps has higher light penetration then the metal halide but it has wrong spectrum so thats why mh is used for veg and hps for flower.and my guess on the browning is either burning from nutes or it is lacking oxygen cause the soil is staying wet for too long. also make sure theres good ventilation and air flow and a fan blowing towards the plants and the light or just the plants if your reflector is vented.