Hydroponics Consistant Damping Off Issues..Please help?

Hi there. I am having a problem with my grow for the 3rd time in a row..and I can not figure this out, so any advice/knowledge would be well appreciated. (I have grown 6 times and the last 3 times this problem keeps occurring).

Info;
Hydro System
400W MH for veg / 400W HPS for Flowering
11 Gallon DWC setup
4 Papaya plants (strain) (Although this happened with short-riders and AK's the last 2 times)
2 Air pumps/stones
PPM at 1100 (flora nutes, as following manufacturer's Instructions) Micro/Bloom/Gro
PH at 5.7-5.9
Fan osculating in room
Temp at 79F
HUM at 21%
Lighting 16/8

Now here is the issue;

I start my seedlings off in paper towel...till 1" Taproot, then place them in an "Aerogarden Sponge" (Not sure what they are made of), and place them into the aerogarden with their CFLS untill they have a good root system, look healthy, and aprox 6" tall. Then I take the netpods out of the Aerogarden and put them into my 11 Gallon DWC system, add a fan and very little nutes....and they look great.
They get nice and thick, healthy ...then BANG! The stem starts to form a bottle neck (Damping off) near the base of the sponge ...they get weak, fall over and break.. This always happens when they are about 3-3 1/2 weeks into Veg.
They have a fan on them to strengthen the stem when moved, but I do not understand what is happening here. Does mildew cause this, or what does?.. This problem only started my last 3 grows (but was set up the same way as the successful grows)..and all plants ended up in the trash from breaking this time again.

Do you think perhaps the sponge from the Aerogarden is to wet and harming the stem?....I HAVE NO CLUE..I have read all about this online...but not much info on a Hydro set up where the sponge is always in the water. Anyone please help?

P.S..I should have taken pics,,,,but I got to pissed off and just threw them all out before I could.

if i were you id grab the sprout and grab a cubei to start them in a paper towl and then brake open a cube not rock wool no way you need these and cut them half way but not all the way down from top to the middle as if you were opening a book let the roots get a lil wet not to wet put perelite under and let the roots grow a lil.. can i see your set up..?? yes stem will get to wet you need to some how not let it get wet all crazzy like that also you need to have 02 in your water oxegen or it will poop on you.. give me the temp in your aroe and give me the enviorment there something wrong.. can you post?? this is mine they do fine but i have had your experience please post pics exzactly what ppm's , ph, water temp, room conditions???

Yea sounds like you are keeping the medium to wet, what is your watering timer set on? Ive always been a fan of rapid rooter cubes, and I only have to water them every 2 or 3 days after germination

I don't like the sound of that sponge. A helpful cure is to cake baking soda around the affected area.

superstoner1 said:

I don't like the sound of that sponge. A helpful cure is to cake baking soda around the affected area.

Click to expand...

or physon 20
but what we need is to get down to the source so something worse doesnt happend..

What size net pots? What is your 11gal unit look like? Maybe lose the sponge and use netpots with collars.

It is Hydro not Soil...no need to water them.

This is the current set up with the same plants that survived they are 3 weeks old. I do not know the temp of the water...but it seems cool to the touch...not to worried about it. I sprinkled some cinnamon around the base as I heard it was good as a fungicide. There is no watering system...the roots are in the water.