My tap water averages 5 ppm. And I live a 1,000 feet from gigantic farms.
I've seen reports from areas much lower than that. In the town I used to live in, the reports were less than 1 ppm (actually they were 0.35 ppm.)
And why would you doubt it anyway? If you don't over stock a tank, if you keep up with WC, if you don't over feed your tank and if you have things like pothos or purigen, it should be feasible to keep nitrates at very low levels. 2-5 ppm is certainly not out of the question. If you have tap water that starts out higher, you just have to make the adjustments to get it lower.
if your tap water averages 5 ppm how would water changes reduce nitrates any lower , plus those test results are averages ? If your tap water is 1PPM nitrate how would a water change reduce levels below or near unless water change is 100%?as long as water is not changed out 100% (which most of us don't), nitrates will keep increasing as time goes by.
Water changes do not control nitrate, but only slows down the rate of increase.
"The EPA sets The maximum level for tap water , for nitrate is 10 mg/L or 10 ppm. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for nitrate, called a maximum contaminant level (MCL), at 10 mg/L or 10 ppm. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation."
Per Seachems website "There are no products on the market that directly removes nitrate (or nitrite and ammonia). Purigen will prevent your nitrate levels from increasing any higher than they were before placing it in your tank (i.e. if your nitrates were at 10 ppm before you placed Purigen in the tank, once you place it in your tank it will not exceed 10 ppm from there on out). " ( as long as resin is not exhausted )
If you have a gravel bed in your tank, feed your fish , run canister filters , keep large fish , using tap water and your aquarium is a closed loop , nitrate levels under 10ppm are extremely unlikely between water changes in an established aquarium .. if your nitrate levels are under 100 ppm , dont stress , just enjoy the hobby.
