Okay, that makes sense. I'll start double-dosing Excel. I just did a 50% water change too. Now for the Flourish and Flourish Potassium, do I double-dose those aswell, all on separate days? Also, should I buy an EI pack from Grean Leaf Aquariums, containing Plantex CSM + B, KNO3, KH2PO4, K2SO4, and forget about all the Flourish products?
Flourish fertilizer dosage tables appear to be designed for low light tanks only. When you have more light than that you have to dose more than the table amounts. Personally, I would order the dry chemicals you listed and use the Flourish comprehensive as a micronutrient mix until it runs out, then switch to the CSM+B, and I would keep using the Excel at double dosage.