[mistergreen]

Yeah, the while leaves are concerning. It's lacking the nutrients to make chloraphil (nitrogen and iron) in the water column.

 

[mistergreen]

Dirt tanks are good for rooted plants, but not so much for floating plants.
I would add a little nitrate & chelated iron. Seachem flourish should work.

 

[mistergreen]

yeah, fish food will help. I just noticed you don't have livestock! Fish poop would help add nutrients into the water column.

 

[mistergreen]

yes, Flourish is low in NPK so little risk of algae. If you add low amounts the risk of algae is low.

 

[mistergreen]

Now you need to feed the nutrient monsters everyday

 

[mistergreen]

True lotuses are in the Nelmbonaceae family and the leaves and flowers grow above the waterline.