When you buy Cheato, it is frequently nitrate deficient and will suck up a ton of nitrate right away. This is what plants do. After it gets its stored levels up, it will not consume nearly as much nitrate. Bottom line, if you want nitrates now you need to dose.
For light, get a daylight LED spotlight. 90-120W equivalent LED bulb. Unless your bulb is 8+ inches above your water, stick with the 90W. But get daylight! don't get soft white, etc. Some people have suggested macros need more red light. This is not true. I tried that and the macro slowly deteriorated. Daylight spectrum makes my macro grow well.