Save my tank!

[jason604]

My phosphate an nitrate always shows 0 but I'm pretty sure it's there ur to all my long hair algae and tons of Ditris I hVe on my rocks n bottom of sump. Phosphate I use salifert and nitrate is seachem. My sea hair I got last week back split and died today. I had a fish die last week I'm not sure it if was natural cause or not cuz all my other fishes r rly healthy. My shrimps n crabs ate the dead fish n by the time I notice there was only the head spine and tail fin left. I'm goin to do another 40g water change tomorrow.