Nitrate Problem

Hi,

I slackened off water changes whilst the Kribensis fry were still tiny in my
community tank. I've lost a pair of rams, no thought I'd better test the
water. Nitrite and Ammonia zero,
but Nitrate is running off the clock, somewhere above 150ppm. The Kribs are
big enough now so I've done 25% water changes every 4 days, thats 3 *25%.
The nitrate is still off the clock.

I mentioned this to LFS who said to check the tapwater, as numerous
customers were reporting high nitrate tapwater.

My tapwater reading varies day to day, but the lowest reading over the past
4 days is 80ppm. So water changes will have very little effect, (probably
caused the problem in the first place). Anyone else have high nitrate
tapwater? what do you suggest ?

Rich