I made a plant starting system, the seeds go to stems rapidly & are weak,Solution?

I made an insulated plant starting system, the seeds start well then grow long weak stems very quickly. Thermostat controlled 2-60Watt lamps for heat , 40 Watt sun lamp for sunlight. Temp is 75/80 well watered. What could I be doing wrong. How do commercial growers grow racks & racks of seedlings without the use of direct light. Better where can I find reading material on commercial growing. Using the net but cannot find the, details I am lookinfg for. Thank you in advance..Glenn

Sometimes I found that if you bury certain plants too shallow they will mature to quickly causing the stems to be weak. I found that if I started plants in clear plastic containers (Kept covered from light with dark cloth) I could peek to see the sprouts coming up. Once they began to almost break the surface...I would apply more dirt to the top. They would then need to grow that much further, becoming stronger on the way.