Been a long time since I posted anything but I think I may be of service here. I'm also using Earth Dust and I admit it was a little confusing at first. I'd have to look at my diaries to be sure but I'd guess this is my twelfth grow with earth dust.
You have to keep in mind that the whole "nothing but water" is a bit of a misnomer in that you actually may need to add things as you go. Why? Not everyone uses the same starter soil. Or the same compost source or amount. Not all water sources are the same...some loaded with minerals and others stripped of them. Different plants need different nutrients or more or less of them than another plant. If they aren't there (in the water) then you will need to add calcium and/or magnesium and some trace minerals, etc... But before messing with that it is absolutely critical to get your pH dialed in. I know the literature all says that there are buffers in there and you should be good to go. HOWEVER, after weeks of pouring acidic water into the soil the buffers can't adjust enough to properly present the nutrients in the soil to the root system. (Calcium needs to be above 6.2) You'll need to help out there. My tap water is currently at 5.8pH. In summer it runs in the higher end of 6.8 or more. I use plain old baking soda to raise the pH to about 6.4 - 6.8 pH and plain lemon juice to lower it. With the color in your pics I'd run a week or so with pH drifting from 6.4 - 6.8 for at least a few weeks. Don't feed exactly the same pH every day, let it drift within the appropriate range. Different minerals need different pH to be absorbed. The damaged leaves will not improve. Watch newer growth to see if you're on the right path.
The other really big thing is watering. You don't want to water to runoff as you will leach out everything the plant needs. Also, don't let the pot dry out as the microbial life will die off, leaving you with nearly sterile soil. And, since you're not watering with liquid nutrients the plant now has nothing to use! Also, you want to keep the microbials in the soil alive and happy. They need to be kept damp. NOT wet. It's a dance for a few weeks for sure. A tiny plant in a 5 gallon bucket is tough to water properly. You need to keep the soil damp/moist but all of that soil getting wet now wicks to the roots of the tiny plant and it struggles to get oxygen. The old instructions of watering a ring around the seedling is still good. But, be sure to dampen the rest of the pot outside of your ring to keep everything else working (don't over water). Then come back to the ring...did it absorb from outside? If not enough then give a few drops or so around the plant and leave it to find the rest of the water.
I wouldn't add much of anything to the water for at least a week until you can "read" the new leaves and determine if you're heading in the right direction. Having said that, I used Epsom salts this morning. My plants (three of them) are 90 days from seed today and 36 days from flip to 12/12. I used 1/2 tsp per gallon of filtered water and pH adjusted to 6.6 for today. Yesterday I watered plain, filtered, water at ~ 6.2 pH. You need to have a pH drift so the minerals can be absorbed at their desired range.
I guess I'm babbling so let me focus in here:
1) The first pic shows a very dry medium. Can't let that happen.
2) The color of leaves and the splotchy appearance is indicative of too low pH for calcium absorption AND over-watering. If you're watering to runoff (or nearly so) and letting the pot dry for a day or two or three and then watering to excess again you are indeed over watering. Even though the total given may not be much over the course of a week the instantaneous effect is too much at a given time.
3) If you think the medium dried out and the microbes may be at risk (or gone entirely) try a tea with Earth Dust. Dan from Green Sunshine has lots of good video instructions to help.
4) I don't know the age of your plants but if you're near the time to flip to 12/12 lighting be sure to get the Boost applied and watered in. If you're still some time away consider an instant tea with Base. I use 2 tablespoons/plant/gallon. I let it work for about 15 minutes while I tend to tent chores. Split between the pots. When the pots are properly watered then stop. Don't be concerned if there is some left over.
I have eventually started to use worm castings ( a half cup or more) every few weeks. I use an Epsom tea (11/2 tsp Epsom, 1 tablespoon molasses, and 1/3 cup of castings per gallon) also every few weeks. The Earth Dust Base tea above. (I use the Base tea if I'm vegging longer or if I had the base cooking for more than a few weeks prior to planting) And of course a Boost tea same as the Base tea in proportions. Molasses added in mid to late flower (1 tablespoon per gallon, sometimes 2 but not every day)
Hope I didn't miss anything or add too much confusion. Good Luck