Originally Posted by Guy

160ppm is going to be harmful to the more sensitive animals in your system. The effects will be long term and chronic, there are rarely acute diseases associated with Nitrates.

How much macro algae are you harvesting from your refugium? This is an indication of how much Nitrate is being removed. If your Nitrates are so high you will need to find a way to increase the macroalgae output. Macro algae of typically limited by temperature, nutrients, and light. In your system you may actually have to add phosphate to receive the nitrate removal you need if you're going to rely on macroalgae for Nitrate export.