[Fiftymeatballs]

You are growing anacharis for your turtle, right? Seems to be a good start. Filters are always important, how bigs your tank? What are you going to top the laterite with?

Flourish fertilizer should be sufficient, it contains a broad spectrum of elements. I personally don't use it. Most people on this site use dry ferts to either dry dose their tanks directly or make liquid like you bought. It's a much cheaper alternative to buy bulk especially when your dosing several tanks.