I received about a 1/3rd of the amount that you see when I planted and it tripled in about two months. Trim the top and replant. This was being hit with about 50 par (medium light in my opinion) with ei dosing and a 1.2 ph drop from co2 in inert sand with root tabs. So it doesn't need a ton of light but it does need nutrients which it sounds like you are providing and good co2. You have good substrate and it seems like dosing and light are good. How's the co2? How long have the plants been in the tank? Mine took about a week to send up new growth but after that it took off. This was in a 40 breeder for perspective.
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