That PPM is so low for those plants. 400 is like when they're three weeks old! I'll be getting my AK up to around 900 before I flip it, 1100 for the flower nutes to start.I just fed more. It should only be another day or so before I water again. I think getting less CalMag last time was not well received. With PPM in only being at 400 at full recommended strength, I think/hope this nute change is going to help. The sprays were for the fungus gnats...which are still here apparently. I saw one fly off of Cheese5 and a one on anther one so...good thing I got another shipment of ladybugs! Which are fertile! Same company as last time. No babies though, I don't think.
Heavy layer of DE on the soil for the gnats would be my suggestion.