Help!!

I have about 20 seedlings that were very healthy a week ago, i think they also stretched too much towards the light at first too. they are begging to droop and shrivel up. The temp is about 26C and 48 Humidity. Im using pro mix seedling mix.
WHATS GOING ON!!!

Over watering would be my first guess. How often are you watering and what size pot?

Other factors: what type of light type/watts? water/soil ph?

ive been using tap and bottled water, have no idea what the ph is. they are in little trays like this

Im also using two U-shaped 13w fluorescent bulbs from a regular desk lamp

Hmm, you could use more light. How often are you watering, I water seedlings about every 3-5 days. Humidity and temps influence that. Also you might want to invest in one of those ph/up down kits so you can test your ph, you'll likely need a way to test and adjust your ph sooner or later.

Edit: what type of soil are you using, a lot of it can cause problems with seedlings as they have to many nutes.

light not strong enough or to far away

well considering the average ph of tap is 7.2, and ph of bottled water usually runs at about 5, id say a ph fluctuation would be my first fix, but pics and lighting type would do us better, watering schedule, any nutes yet? answer those, and we can help ya

i have grown with tap water let standing for min. 24 hours, and have never had any problems.