My 125G project 2023

Hi all,

Some weeks ago I brought a second hand 125G tank, which I foresee being my discus forever home eventually.. (If I ever get the nerve to fill it completely lol)

It is currently half filled, has 2 sponge filters & 2 air curtains running & has a large driftwood in it. The driftwood has been submerged for 5 days now, but will not sink, it was suggested to tie a rock to it but I don't know what type of rock to use, that wont leach into the water & filters? It has also turned the water discoloured (Brown), and I am not sure what to do about that? If anything at all at this stage..

I plan to buy a canister filter & 1 internal filter next week for this tank, I already have the heater, it's just not installed yet. I also need lighting for this tank as the 4 foot light is not ideal just sitting on top of the lids. I was looking at a couple of hanging lights that clip onto the back of the tank wall..

Here is a video from a couple of days ago, everything is still the same. There is water marks I can not remove on this tank, that's what you get buying second hand stuff I guess :)
https://www.youtube.com/shorts/AqX_mQDIiCc