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A water change should fix high nitrates?

What is the nitrate reading? When was the last water change? What size of tank and fish in it?

Yes water change will reduce nitrate and lots of plants will also. You should be able to keep nitrate at acceptable levels with regular wc and vac.

it houses a raphael and 2 ottos (had 3 one seemed to dissapear) in a 29 gallon. Last one wasn't to long ago but yea the nitrate was thru the roof. i did another water change and made sure to vac well. gonna test again later tonight

Nothing dumb about the question.

Nitrates are the end product of nitrifying bacteria. One bacteria eats ammonia and produces nitrIte. The second bacteria eats the nitrIte and produces nitrAte. The first two - ammonia and nitrite, can be lethal even in lower amounts. Nitrates typically rise slowly, if the tank is not overstocked.

Otos, in particular, don't do well in high nitrates.

Nitrate levels, in a non-planted tank, are best kept below 40ppm for the health of the fish. Ideally, you want to target it to be less than 20ppm.

In a planted tank, nitrates can damage the plants if they are too high. A good range for a planted tank is between 5-15 ppm.

When reducing nitrates in a tank, the best approach is to do daily, partial changes of 20%, using same temp, conditioned water. This will bring them down slowly.

A tank that is not overstocked, should not require changes more than 20% weekly, especially if planted. If you are understocked, let your nitrates guide your water changes. If you know that you want to keep them between 5-15, then see how long it takes your tank to get back to 15 when you take it down to 5ppm with daily water changes.

The effects of nitrates on health is becoming more understood today than in years past. In natural bodies of water, the nitrate are quite low. Fish exposed to high nitrates, long term, suffer slowly deteriorating health as the immune system becomes suppressed. We now know that it causes dilation of blood vessels. In fact, in goldfish, a "varicose vein" appearance can take place in the fins when they are in high nitrates. Some people mistake the redness for septicemia and dose the tank with antibiotics.

BTW - tanks that have large mass fish (i.e., goldfish, oscars, etc) will produce more ammonia. Ultimately the amount of bacteria that grows is proportional to the amount of food (ammonia) available. Therefore, when something like a goldie is in a small 10 gallon tank, the time in between water changes will decrease as the fish grows - dramatically. This is why we suggest 20 gallons minimum per goldfish. This results in weekly water changes to keep nitrates at reasonable levels.


Hope this helps.

Last edited by Cory_Di at 05-Nov-2004 19:54

just did a test a couple hours after water change...looks like 6.8 ph, 40 alk, hardness soft, nitrite 0, nitrates still seem very high though.

Last edited by azrael_darkness at 05-Nov-2004 21:02

What is "very high"? Can you quantify or provide a range?

Nitrates need to be brought down slowly. Just keep doing daily, partial water changes and they will come down. Once you get them down to about 5 ppm, see how long it takes for them to climb to 20ppm, or 15ppm for a planted tank.

You can do 25% changes, but just make sure the temp is the same as the water temp. Otherwise you risk bringing on ich, if it should drop.

Last edited by Cory_Di at 05-Nov-2004 22:27

it was like 160-200 maybe more the color was kind of in between and the chart only goes to 200, but the 2 ottos,and raphael catfish that are in there are showing no sign of stress.

Definitely high and not healthy. Being gradual, the otos have dealt with it. Since bringing it down will be a pain, shoot for 20% changes every day to every other day, depending on your schedule. I believe once you get them down to 5ppm or so, you'll only need to do it once weekly, or bi-weekly, depending on your bio-load (and ultimately, how fast it takes your nitrates to get to 15).

You are lucky you haven't had an algae explosion with nitrates that high. Also, I might add, check your water source for nitrates. If you are using well water, the level of nitrates can fluctuate based on time of year. There can be more in the spring when leaves the fell in the fall are decaying in thawing snows and waters.

If you find high nitrates in your tap source, use something like Prime or Amquel Plus for water conditioning as it treats the water for nitrates. You can technically use it in your tank to bring them down, but you can also kill your fish if you overdose the stuff. I had a close call when work interferred with my ability to do water changes on my goldie tank (heavy bio-load). I put in a little too much amquel plus trying to keep my nitrates and bay and the poor little buggers were piping for air within minutes. I had to do a 40% water change . What you may try with Prime is to add 1 drop per gallon or just slightly less. I attempted the 5x amount suggested if you need to bring things down faster. It does state that the tank should be well oxygenated and my goldie tank is. However, I just put too much in. I wasn't carefully measuring. Nevertheless, I have a little more respect for the stuff and would do less than full dose.

Last edited by Cory_Di at 06-Nov-2004 11:30

I might need to try a different test kit or something because i do constant water changes, and vaccum the whole gravel floor but still it insists my nitrates are high I can't figure what else to do otherwise

Did you check the nitrates in your tap water? Some people have them. If you do, then treat the replacement water ahead of time with something like Prime or Amquel Plus. These will remove nitrates.

You can use Prime to help bring down your nitrates, but you must be careful. It can rapidly steal the o2 from the tank making your fish pipe for air at the surface. Don't overdose. I think you will find if you add just one drop per gallon or just less than that, it won't be too much. Do this two days in a row after your water changes, then wait a few days and repeat the water changes and another two days of treatment.

I highly recommend the Aquarium Pharmaceuticals test kit for nitrates. It is the most economical and easiest to read. All test kits need to be replaced if not used within a reasonable time.

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