I can't speak for Kudo but I assume he meant because the ambient heat the ballast gives off it will raise your temps higher and you'd be at risk of fire. Yes I have read too lots of places you can't burn with organic nutes or it's hard but I have to disagree. Especially from my experience. The things I told you are all things I learned on my first grow so trying to help you learn from my mistakes
If it was me I would flush. If you can get some distilled water or rain water would be perfect. The distilled water will help strip all the excess nutes out so she won't continue to burn every time you water. Make sure you use double the amount of water per your container... So for example if you are using a 1 gallon pot use 2 gallons of distilled water to flush. If you want to "feed" your seedlings in the future the safest way with Autos is to purchase some kinda of Myco or Beneficial Bacteria powder that is NOT a nute but it is a high powered inoculant that will feed your roots. It won't burn them or harm your plant in any way. If you want more info I can give you some links for you to check out. I use it, lots of the Masters use it. There are many brands and we basically all use our own stuff but they are all very good. Also, if you must transplant or you need to to weed out males or for space you can tier transplant which is a Non Stress way of transplanting and you can do it and basically not harm or stunt your plants.
It is a lot of stuff to throw at you I know lol but I'm right there with you bro. I started at the end of May and I can't tell you how much I've learned and I'm more than willing to help you any way I can. If you need anything PM me or just post it here. I'm subbed and I'm sure you will get all the help you need. Kudo is a Master and I would take his words seriously too. No one here will put you in the wrong direction. We are all here to help bro.
If you want to check out a Myco product here's the one I use...
http://www.humboldtnutrients.com/root-stimulants/myco-madness/
Just for reference... Yo udon't have to go out and buy that one. Any myco product with similar ingredients will help your seedlings out tremendously. Especially organics!