why are my seedlings dying?

i thought hydroponics was supposed to be easy, im barely keeping these guys alive, they were doin fine for the first week in the bubbler (300 ppm), then they were looking a little yellow, so i changed the res and put in some foxfarm nutes (600 ppm)and the next day the roots were covered in brown slime, so cleaned everything out and gave em some lite nutes(200ppm and hydro peroxide), and they kept yellowing alot more, then added more of some miracle grow nutes i had since i dont trust the foxfarm and bumped to 500 ppm, and they are sproutin some new green leaves but the yellow ones might be dead already, this is tough shit i thought i was doin everything right! any suggestions?(im using dist water and nutes but not checking and doing PH changes, this may be problem?)

You are going to fry those little girls. To many nutes, and fucking with shit I think. Add pure clean water and leave them alone for seveal days. Nute burn sucks. Those yellow leaves are lost and will fall off.
Don't fuck around too much with them. Trust me I know from my own experiences.

Yeah dude gentle on the nutes, they're babies. And don't muck around with them too much.

Thats fuggin funny how you just kept resorting to more nutes. Obviously you havent been doing your homework. If you stop your madness right now, you may be able to spare them. Listen to these guys.

You said your not checking your ph. That could help out alot also. Spend $10 on a ph tester, it will pay off becuase your plants might live.

I haven't had too many problems, just adding nutes to find a threshold for a plant. I'll say what I do, not to say it's the right way, but it is the way I have done it without too many problems.

I usually run 2 seperate resevoirs. If I didn't have a PPM meter I would mix according to the bottle instructions maybe a 1/3 less. Mix the stuff up real good and check and adjust the PH. Run one of my airstones in it for a day with it covered up. The next day I stir it up one more good time and check the ppm (if you have a meter) and check and or adjust the ph. Change out the containers by just swapping lids.

As far as your root rot or possible pythium disease, I would refer to growfaqs up top and look into possibly using some h202 to help suppress this problem. Usually root rot is caused by high temps, lack of air, or in this case I'm sure you could have of a problem of overnitrification causing the death of the plants leading to a breading ground for organisms down there. Good luck.

Most people tell me no nutes at all for the first 2 weeks. Or no nuts for 1 week, and very little as in less then 20% strength the second. Then build up the strength of the nuts slowly.

If they were my plants I would flush them with PH'd R/O water until the PPM of the run off is below 150 or stops droping, and then put them in nothing but Ph'd water for a week.

yes small plants need far less nutes than mature ones. i give them 150 ppm until they are about 6" tall, then 250ppm until a week before flowering. at this point i feed them nothing but water. this does two things. it preflowers them, and it forces the plant to grow roots like a mofo. I grow using DWC bubblers also. the roots are browning because the nutes are too high. they will die if they are not needed, which is what is happening. PH is one of the biggest factors. Since they are young and you should be using very little nutes, you will need to add ph down to 5.5-6.0 Also- as the roots pop out, pick them off and cut them daily for about a week. trimming roots does the same thing as trimming the canopy. Roots will go nuts. Roots are the key to huge yeilds. the size of the plant matters little compared to the size of your root ball. Focus on keeping them white. Put some hydrogen peroxide in there once and awhile. (raises PH be wary) If they start browning its either too much nutes or not enough Oxygen. Make sure your netpot isnt saturated all the time. you want to drop your water level once roots start to bust out so they get plenty of oxygen.

Switch to soil.