I had to log in. Lots of questions. I will try to help. You need alot of reading too. Follow some grows.

First PH water is good but what kind of water ? If r/o or distilled you need cal-mag plus. No hurry.

Seeds are poppin ? Yes put them in the rockwool. Is rockwool the only medium and what size is the rockwool ??? Before you put them in RW sling the RW like a paint brush to get out excess water. A few drops of water or so when you see it start to dry. Seeds need only water for first 2 weeks of life. Then 1/4 nutes after that for a few weeks. The sooner you get them in the main system the better off they are. In a Deep Water Culture system you want to keep the water level just under the net pots and bubbles splashing the bottom of the net pots. To start you may need to water by hand from the top till roots hang into the water.

Now nutrients. I think there is a sticky at the top of the page for GH floro mix. It should be by the gallon. I ran the lucas formula with just micro and bloom. Saves money and I saw no dif. Do a search it's here..

Do you have a PPM or EC meter ? If you use R/O or distilled water you can get by without one but any other water you need to know. There is a sticky at the top of this page about Water and cal-mag plus. Please read.

Let us know how it's going Plaese. You maybe helping the next one in need.