How accurate is Salifert N03 test kits?

[WVReefJunkie]

I have a 220 Gallon aquarium and have been testing Nitrates with a Salifert N03 test kit. The results are always 50 ppm. I don't have any algea issues, but have had some sps stn for a while. I have increased water changes from 10% weekly to 20% weekly. It doesnt seem to lower the Nitrates, is this a accurate test kit to use?

 

[cloak]

If everything looks good then it just might just be a test error. When your doing these water changes are you removing all the poop/detritus too? Water changes can be a bandied sometimes if your not nipping it in the bud.

 

[WVReefJunkie]

No, I just have been changing the water. I guess I could drain the sump and suck detritus off the bottom of the sump.

 

[cloak]

A high nitrate reading is usually the result of too much "crap" in the system. Your biological filter is struggling. Remove this and you might lower that. GL.