Hello,
In my tank Rotala H'Ra old leaves are melting. I have attached few images of the plants. I'm Unable to find the reason for this. Could you please help me.

Tank Size: 3ftx1.5ftx1.5ft
Temperature: 27-28C(82-84F)
Fertilizer: Tropica Specialized Fertilizer(I'm Adding 8 Pumps(16ml) after water change in every weak)
Light: WRGB LED Strips
Substrate: Dymax Base soil
Co2: Pressurized Co2(3 Bubbles per second)[Drop checker is showing green in the photo period]
Filter: 950 litters per hour Canister Filter
Lights on 8 Hours Per day
50% Water Change every weak.
dGH:7-8
Nitrate: 5-10ppm
Ammonia: 0ppm

Have a pest snail problem also.

Please see the attached images and help me to find the reason and a solution to the problem. Thank You.