Are nitrates found in your tap water, which is soft water by the way, going to slow down the cycling process in a tank. The tap water test 5.0ppm and my oscar tank tests 20ppm. I am just wondering? Oh and nitrite is zero in my tank, ph is 7, and ammonia is .25, which I think is to high.

Parrotman32 wrote:


I believe most tap water contains some degree of nitrates. ...I think you can test it with the same test kits you use for your tank water. I have heard of ( I would assume very rarely) some tap water testing as high as 40...such as water supplys near a golf course which use certain chemicals...also runoff from fertlizer use, septic tanks, sewage, and erosion of natural deposits.

Anyways, I would be highly skeptical of any trace amounts of nitrates in your tap water having any serious impact.

Funny you mentioned this b/c tonight when I tested I got my first ammonia readings...and higher nitrates too. I would surmise b/c I replaced one of my mechanical filter cartridges yesterday. Also, I had a put a large sponge infront of it a few weeks ago, and when checking the filter I noticed the water was being pushed over the filter media due to lack of space (the sponges were crammed in there) and running back into the tank without going through the media.

Almost all of us have nitrate present in our tap water. NO it will not affect your cycle process. what will affect the cycle process is chlorine in tap water. even when cycling a tank you need to treat the water with a conditioner.

what is your position? do you have fish in the tank? have you just set up(empty tank)? if you are trying to cycle the tank you need ammonia so 0.25 isn't that high. if you have fish in the tank you don't want the ammonia to get any higher than 0.25. tell us a bit more about what you are trying to achieve and we will try to help a little more.

Parrotman32 wrote:


I agree with the others, nitrates in the tap water is not going to disrupt the cycling process. 20 ppm is well below what we would consider to be too much. However, how long after a water change did you test for your nitrates? you will find that nitrates will slowly rise until it reaches a level where you will need to carry out a water change.

.25 in your situation is not going to cause any harm to your fish. However, there shouldn't be any ammonia in your tank so I would advise you to reduce the amounts of food going into the tank for a few days and see what happens with the ammonia. Make sure that you always use a conditioner when he change water. What happens is you sometimes kill off some bacteria which is why you get the small ammonia spikes. Sometimes it's something you can't avoid because you might have to turn your filters off for longer then you wish if you are carrying out lots of tank maintenance, or changing lots of water.

Nitrates are the end result of a cycled filter so nitrates in tap water wont affect the cycling process.

The nitrate level in your tap water is the minimum level of nitrates you will get in your tank. My tap water nitrate level is 23, I had the water company test it. I then complained that I thought this was too high and they told me that nitrates up to 50 are allowed (im in England). This level is very annoying as I have to to be very careful not to let my nitrates get too high!