Need a little help

[Giorgio Lamp.]

Hi everyone,

I set up my new tank a week ago and I haven't stared to put fertiliser in yet however the anubias leaves are starting to turn a brownish color. I tried to wipe off some off it and it comes off easily. Do you think is just sediment or could it be a lack of nutrients?
I used the Jbl pro scape soil and when I filled the tank the water was really black. I'm changing the water every two 2 days as is recommended on the soil package.

I'm hoping it's just sediment from the sand but I was wondering if anyone could help me in case it could be something else.

Thank you!
-Giorgio

 

[roadmaster]

I suspect diatom's which will go away on their own as the tank matures and bacterial activity increases.
May also witness fungi on the wood if it is new as opposed to seasoned and this too goes away with time.