6 hours all up in total.
The split period may not be essential if plants are used to a single period. The idea is that plants can respond to the increased light coming on faster than algae or that in low CO2
tanks, it gives a period of time to recharge CO2
in water. Need a plant expert there.
Generally it's suggested to cut back lighting to 6 hours and then start working on the rest of the tank. Once all sorted, gradually increase lighting again. Lighting is the constraint and ferts/CO2
abundant. The other way around from what I can see, the plant has to rob parts of itself to match the light.
For BBA I did:
- reduced lighting to 6 hours and lower intensity.
- made sure my CO2
dosing was consistent/stable and it came on at least an hour beforehand. Goes off about 15mins before lights.
- picked up some algae eating snails / fish. The fish are ok still, the snails didn't work so well.
- glut (liquid carbon) dosing which I've found discourages algae.
- increased ferts dosing and added substrate ferts tabs.