Hi.. don't worry.. these things can happen. I c that u r using gravel as ur substrate. Wud highly recommend for a nutrient rich substrate. It definitely helps. And looks like u don't use co2. Do u dose excel daily? For a non co2 tank ur lighting intensity s too high. Excel s not as efficient in supplying co2 as pressurized system. Wud recommend 1wpg for 8 hrs with daily excel and adjust ur plant inventory into a low tech one. Otherwise add co2 system.
Sent from my SM-G920I using Tapatalk
Sent from my SM-G920I using Tapatalk