Lighting help needed

Good evening everyone ☺️
I have a 500L planted aquarium with only anubias in and normally I leave my lights on for a total of 13 hours

I have purchased myself a timer and heard that apparently the lights only have to be on for 8 hours
But what I'm struggling with is

Should the lights be on for an entire 8 hours or could it be on for 4 hours in the morning and 4 hours in the afternoon

 

This is what my anubias leaves looks like and what I'm trying to fix

 

I leave my lights on from 6am till 9pm and somedays forget to switch the lights off. I dont have problems with my anubias and they in with Mbunas and Peacocks. So maybe be a nutrient issue and not a light issue.

 

I don't know why my anubias have this black edge

 

Best to have a solid block of lighting. You can put it on anytime - for example, my office tank's lights run from 09:00 - 17:30 while I am there. My kitchen tank runs from 12:30 - 21:00, which is when I am most likely to be there.

Those edges are a combination of old decay and nutrient deficiencies (I cannot say exactly which one). Trim the old dead leaves off closer to the top of the stem - as new leaves grow out of the stems. This will spur the plant on to grow new leaves provided you add some liquid fertilizer to compensate for the nutrient issues.

 

Thats purely old leaves, just cut them off, nothing to do with lighting.
Even your garden plant’s old leaves start to die off

 

More information on the lights? How many lumens do they produce? What is your fertilising schedule? Water parameters? Ammonia, nitrite, nitrate, PH and if you know GH/Kh.