aquasoil maidenhead aquatics

I have a new 620T 130L tank and 5 days ago moved all my plants, fish and established Eheim 2213 filter across to it from my old 56L tank. I decided to have a base of Aquasoil from Maidenhead Aquatics https://www.fishkeeper.co.uk/product/aquasoil capped by my old gravel to benefit plant growth...