Fixing Damping Off and Yellowing Tomato Seedlings

First year starting vegetables from seed. '4th of July' tomatoes came up but most died; two remain, yellowing. Using soilless mix, kitchen fluorescent light, water when dry. What went wrong?

Diagnosing Seedling Failure

Damping off (fungus) is likely—caused by: contaminated soil, poor air circulation, or overwatering. You're using sterile mix, so check: (1) Sterilize reused flats/pots (1 tsp bleach/gallon water). (2) Remove humidity dome at FIRST sprout—air circulation critical. (3) Add a small fan 3+ feet away on low/rotate. (4) Don't overwater—drainage holes mandatory.

Light: 14 hours/day under fluorescents (or 1 cool + 1 warm white bulb), 3 inches above seedlings. Fertilizer: After 2nd true leaves, use diluted fish/seaweed emulsion (organic, no salt buildup). Resources: Nancy Bubel's "New Seed-Starters Handbook" + linked university guides.