After numerous total water changes over the days and all the precautions that I can take not to disturb the substrate, I finally have what I'd call an acceptable clarity.
I finally got some plants. I did a final (I promise) water change before putting the plants in. I did all I could to minimise cloudiness. I drained the substrate. with airline tube. I use airline tubing to siphon the water back into the tank for the first few inches, then with a small cup cushioned with plastic bag, then with a pump cushioned with a cup. It was crystal clear right from the start, right until I turned on the Seio that is buried in the substrate.
Water has since cleared up a bit, but still cloudy.
There are two problems. The first is the plants are bigger than I thought.
I should have gotten the smaller ones. I thought it was a "first stage" purchase, but it ended up as "almost done". This may seem anti climatc.
The light has poor spread, pretty much all the lit area are filled with plants. The unplanted area are what I'd call the "light spill" zone.
The second problem is, I think it is harder to aquascape a riparium-ish tank, since I have to take care that it looks good both from the front and the top. The front view part is basically regular aquascaping. The top view part is more like floral arrangement.
I think the look isn't what I wanted. I don't quite like the jungle look, but I have since learnt that whatever you do with anubias, ferns and wood it is going to have that jungle look.
And the front view is quite crappy. Since when I stand in front of the tank I actually looked at it more from the top that from the front, so I prioritised the top view. Any advice would be appreciated here.
Also the anubias is in a bad shape. I heard that they are grown emerged at the farm. But I guess being out of the water for too long the leaves are rolled up. The leaves that has shorter stem seems to look better than those with a longer stem, even if those short stem leaves are actually not in the water. I hope it recovers/adjusts.