Changing substrate in planted tank
Brand new user here. So I've had my 130 Litre tank for about 3 years now. The substrate I have right now is peat moss with fine white sand. In the beginning the idea was that the white sand would cover the peat moss but over the years they mixed so it looks ugly with patches black, white and brown. So I want to change the substrate to something that is easy to maintain, clean and can also anchor plants down.
So question: I've been doing some research and I hear aqua soil is a really good brand.
1: If I use aqua soil do i need to cap it with something on top? (eg: BDBS)
2: How long will aqua soil last before running out of nutrients?
3: When it runs out can I replenish it with root tabs?
4: If I use aqua soil with BDBS on top. how do i clean it? How hard is it to make sure they two layers to mix?
The attached picture is from 2016, so the sand+peat is much messier now. Also I had a massive die off recently so lots of the plants and fish are gone now but you get the general idea.