Am I caring for a dead plant?

[floranewb206]

Lol. It bloomed for a really long time. Bought May last year, and still had flowers until about September. Then the leaves went limp, some roots died and I trimmed them. Now there's only one healthy looking root..

I water thoroughly once a week with dirty fish tank water that has a good amount of my aquatic plant fertiliser (Potassium, Phosphate, Iron, Nitrate)