carpenterwrasse
Taking out LR will not lower your Nitrate, you do not have too much LR.

Please give us more information.

What type of substrate do you have?
How long has your tank been operating?
Are you using a sump?
Are you using a skimmer?
How often do you do water changes?
How much water do you change each time?
What tank inhabitants do you have?

Help us help you by answering the above questions to begin with.