no more "custom" soil blends mate, keep it KISS,... Use a single high quality soil brand, and blend with the super soil if needed... SoHum, KIS say to make a center pocket of milder soil to start the seedlings in, them use the straight dope to fill around it... I make a 32oz to 1/2gal size mild core, depending on pot size...
GTF away from Fuxfarms, who needs to roll those dice? Are you West Coast/CA? You may be able to get Sanctuary Soil brand, Victory Mix for auto's, Empire Builder for photo's,... Royal Gold King's Mix is a great (true)soil too, my fav' for the tent... Blends nicely with Sanctuary soil if you want things heavier, as the KM is very light... Roots Organic original is OK too, more readily available...
Your tap water is 270ppm?

that's very hard, full of minerals that can cumulatively start to drive pH up, mess with availabilities of some nutes, loading the soil up with CaCO3.... Consider using different water... those self fill machines are a good way to go!
You have plenty of time to start feeding for better results, get a base bloom nute going,...