Help with nitrates

[surfrat29588]

I'm having problems with the nitrates in my tank... It seems to want to stay around 80 on the API reef test kit I have. I've done about 5 water changes in the past month. I've had the tank up and running for almost three years now with no problems at all. What can I do to get the nitrates down other than just doing water changes. Ause that doesn't seem to be helping. Also I've noticed the past week or so that I have a bunch of the little starfish everywhere and also some starfish that I believe are small bristle starfish. In all I've lost five fish due to this.
My tank is 90 gallons with a marineland 530 canister filter and I have about 70 pounds of live rock.

 

[snakeblitz33]

I need full parameter readings.
You also need to throw away your test kit and get a better quality one like salifert or seachem brand test kits. Check the dates on your API kit, and I bet they are waaay out of date. Take a water sample to your local fish store and see if they can double check your results... That is first before you go into everything else.
Is your canister filter the only form of filtration that you have? Do you open it up and clean everything out and replace the medias once every two weeks to thirty days? If you don't - that's definitely and most likely one of your problems.
Fish don't die because of high nitrates most of the time. They have to be well above 150ppm plus plus to actually do any harm. So, this means there might be something else wrong in the tank.
I would love it if you could post some pictures of your tank so that we can get a better idea of what is going on.