Plants turning black - Help!!

[Robmana]

You don't want to reduce the lighting too much. Just reduce the time or the intensity for a couple of weeks and see if there is an improvement. Don't reduce both time and intensity, just do one or the other. And only reduce the time by 1 hour.

Plants need at least 8 hours of light per day.

Ok done!

 

[FishHobby99]

I purchased liquid CO2 in a futile attempt to grow red plants. Quickly read stuff is useless afterwards, but may be of some value as an algaecide. idk. Not using it at all.

 

[Byron]

Several posts since the first, and frankly I do not agree with some of the advice, so will just provide my assessment forgetting all other.

The fertilizer, can you provide me with a link to the manufacturer so I can see what it is? Online I cannot find it, and other similar products do not seem to be this one. The wrong fertilizer, or one that is high in phosphate and nitrate, can be real problem sources of algae.

As for the light, you want white light that is high in the red, blue and green. A Kelvin around 6000K (6500K is common) or a high CRI (colour rendering index), is this stated anywhere on the unit or instructions, or online?