Water Parameters after Hurricane Off!

One 20% water change will not bring phosphates back to zero. It will lower them to 80% of their previous level, so 0.8ppm. Provided there aren't anymore phosphates being added, you'd need about 5 20% water changes to get it close to zero. I'd recommend doing the 20% water change asap, then doing another one 24 hours later. That will remove about 40% of the pollutants in your water. Should help alot. Then, depending on how well everything is doing, I'd do a third one 24 hours after the second one if you feel it would help. The water changes will buy you time while you try to figure out where the pollutants are coming from.