[NCTIM]

Here's what I think.

Remove the heat pad. The warm soil will encourage fast growth which will result in spindly seedlings. Carolyn and others have stated that bottom heat isn't needed for Tomato seed germination. It will hasten the germination period but when a few pop up remove the pad.

The ambient air temperture should be around 65 degrees or so. Cooler is better than hotter at this point.

Be sure the shoplights are within an inch or two of the seedlings. If not, they will stretch towards the light. Run the lights about 16 hrs a day.

Water at a minimum. Good and dry before watering will be better than maintaining a damp mix.

Running a fan so that a slight breeze is blowing across your plants will make the stems thicker.

Transplant seedling to an individual container when the first set of true leaves appear.

If all efforts fail and you still have a spindly or leggey seedling with it's first true leaves, don't worry. The seedling will be transplanted deeply. Set it to a depth that's just below the first set of true leaves.

The same things apply to the new transplanted seedling or they too will get leggy.

Hope this helps,

Tim