whats the problem?? please help !!!!

My friend said too little nitrogen but im not sure. Can someone please help???
ph is at 6.1, ppm is 470, temp is around 70 with 50% humidity.

The are in coco perl and get water every 8 hrs by ebb and flow with floramicro hard water and florbloom with volcano guano in a 25 gallon res.

I will be waiting for a response.

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