Those plants in the front corners- what are they?
I'd move then away from the sides... Perhaps change the angle of the driftwood, move it to the right about 8 inches, and put those bushy plants about 9 inches to the right of the wood?
(There's a 'magic number' for aquascaping, and simplified it's about 1/3 So divide the tank into thirds and have something to catch the eye where the 1/3 lines would be... wow, that's too complicated...)
I'd also move the vallisneria (?) to the right... I think the only complaint I have is that it looks manmade and "rigid". Introduce a little chaos, and it will look better imo.
I'd also be careful- those shells will raise the kh of the water.
Oh, and one more thing. Red plants will work in low light as long as you choose the right ones... Barclaya and crypts do well and are red-ish. I'd also add a foreground plant- perhaps dwarf sag or Isoetes?