Please help with plant problem.

My friend is growing just one plant. Its under one 150 watt hps light fixture in a growbox. The light is approximately 15 inches from the plant. The temperature stays around 84-85 degrees. Soil is Sta-Green which contains:nitrogen,phosphate,potash,,potassium,canadian peat moss, and perlite. Has proper ventilation and a fan flowing fresh air over and towards the plant. He waters every 2-3 days when the soil is real crusty, how much water should he pur into it?

The plant is exactly 20 days old, its approximately 5 inches tall with 25 visible leaves, Is this good or bad?

The problem is , maybe 3 of the leaves has very small yellowish spots on the outter tips of the leaves, and the other leaves look a pretty green healthy color. What could be the cause of this?

Water until some comes out the drain holes.
Size sounds good.
Yellow? pics would help

u need to water as mentioned above , the problem is the "crusty" feeling of the soil

whats the pot size / soil volume ?

Sounds okay to me. Maybe a minor over-fert. Is it only on the bottom? Only on top? Get those temps down if possible. If you can get the temps down you can move the light closer. You can do what smucker G said, but doing so too much will strip your soil of essential nutes. Pictures would really help. What size pots are the babies in? watering every 2-3 days usually isnt healthy unless you have pretty small pots. My plants are in 10'' pots and i water evry thursday. A strict water shedule is important. It's also very important that your soil dries out in between water cycles, but not 100% dry, zero moisture... but you know... And when you water give it a THOROUGH water. I water my 10'' pots with a little over half a gallon. Enough for the water to seep out and get sucked back up within 30 mins. Sorry for the rant.

Hope I helped at all!

my pot size is like 8-10 inches in height , maybe like 7-8 in width? so how much water should i pour into that?

the burn is only on the top , upper end tip of the leave , jus a few specks at the tip and middle area of the tip .. not that bad or noticeable really , jus wanted to fix the problem before it became and issue.

as much as it takes for water to seep out and be sucked up. If theres water left in your drip pan after 30 mins that is GOOD, becuase you know that your plants have absorbed all the water they can. Discard the water left over. how far are your lights away. What lights are you using?