High Nitrate, Low Ammonia And Nitrite?

[homgra]

Hello guys just wondering if you guys may know why my nitrate levels are so high. I have a  6 month old 40 gallon tank and my readings were ammonia .25ppm, nitrite .25ppm, and nitrate 40 ppm. I did a 10 gallon water change a few days ago because the nitrates were at 55ppm! Also, how often should i replace the filter on water filter? 
 
Thanks

 

[eaglesaquarium]

You should not replace the filter, but merely give it a good rinse in old tank water about every month.  Weekly water changes of at least 25% or so.

 

[Ninjouzata]

May I ask what is in the tank (and how many) and what your water change schedule is like?

 

[Zikofski]

yea should never replace the filter. and 55ppm is not that bad, I've seen excess of 100ppm and no deaths, the 0.25 nitrite and ammonia tho is an issue if they are correct readings a 50 to 100% WC will help solve all the issues, for the nitrate, how often do you do a WC? it is recommended to do 20 to 50% weekly.
 
do you have plants in the tank? they help keep nitrate down maybe look at getting some plants for the future? also have you tested your tap water for nitrate, my old place had 40ppm nitrate in my tap water so there was nothing i could have done with a WC and my fish adapted fine