nitrates reading off the chart.....

[CEDRIC]

question:i have a fish only tank(aggressive)six fish....(so im not to worried about it),but its not good to have it that high even with a fish only tank.....fish seems to be doing well...all are eating and very active ....i have done several water change about 20% every three days....but no change in nitrates....i thought it was maybe my test kit but i took some water to aquatic warehouse and it was verified...now my ammonia and nitrites were reading high about a month ago and realized that my skimmer wasnt working properly...got that fixed and now they read almost 0...but i cant seem to get my nitrates down....any suggestions



thx in advance

[Bug_Power]

make sure you don't have anything decomposing in the tank. How long has the tank been up?

[CEDRIC]

all are counted for.....i dont have a clue what it could be

[Ross]

My guess is your using tap water which has high nitrates to begin with.

[NaCl_H2O]

Six fish? What are they? How big is the tank? An aggressive tank requires aggressive filtration, just ask Don-n-sa! Probably due to waste being converted to nitrites -> nitrates and not enough equipment to remove the nitrates.

[matt]

If you do a 20% water change, that leaves 80% of your nitrate in the tank. Then if you do another right away, you're not removing another 20% right away, only 20% of the 80% still in there. The trick with a big water change is to do as much as you can at one time, maybe 50%, then another 50% in a day or so. Then you've removed 75% of your nitrates. Probably a series of 50% water changes will knock the nitrate down temporarily, but you'll still need to address the issue long term.

Maybe if you post more about the type of filtration you're using, we could offer better advice. With large fish, you'll produce alot of nitrates and phosphates, mostly through fish pee and the other type of waste....I think the best solution long term would be to set up a big refugium where you can grow a large colony of macro algae to utilize the nitrates and phosphates, and invest in a really strong skimmer; the strongest you can afford. Manufacturers' "ratings" on their skimmers are just a marketing tool; there's no standarized way of measuring what a skimmer's capacity really is.

[GaryP]

Even with a state of the art filtration system you can have problems with high nitrates in a predator tank. Don-in-SA has one of the best filtration systems I have ever seen and I know he has had problems with nitrates in the past. Predators simply produce a lot of waste and a lot of waste equals a lot of nitrates. Its a simple matter of your bioload exceeding the capability of your system to handle the load. There are two solutions: 1. Decreasing the bioload, 2. Increasing the capability of your system to handle the load.

Its not a matter of how many fish you have, but the size and type of fish you have. Two equal sized fish can produce totally different amounts of waste. For example, a tand and a triggerfish. The trigerfish is going to produce more waste because it survives on a higher protein based diet. High protein foods such as frozen meats contain a lot more protein then something like spirulina flake which has more fiber. Protein is the source of most of the nitrates because they are high nitrogen compounds.