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FishRCool 03-11-2008 10:19 PM

Help with Nitrites....
I have a fairly new tank. It has been 2-3 weeks since the last water change 25%. I was going to do a 25% water change today because I am noticing evaporation but I think there may be a problem. Basically everything tests fine: nitrate, hardness, chlorine, alkalinity, ph, and ammonia but the nitrite says Danger ...around 9-10. Is this ok? When should I do a water change and then how often do I do a partial water change and change and filter....not the bio filter but the filters with the carbon? The last time I changed the carbon filters was Feb 17th. 40 gallon, 3 parrot fish, rock, decorations, fake plants, basic lighting, also 3-4 weeks ago I added beneficial bacteria in a bottle to the system and thank God that got the ammonia to go down. It was consistantly HIGH but I think I was feeding the fish too much and am no longer doing that.
Please help.

conger 03-11-2008 10:33 PM

well, from your description it just sounds like your tank is going through the normal cycle of a new tank... how "fairly new" is it exactly? The normal cycle is: fish waste and uneaten food turns into ammonia... one kind of bacteria grows to convert the ammonia into nitrites. Next, a new kind of bacteria grows in addition to the first to convert the nitrites to nitrates. Water changes are done to keep the nitrates in check, but the resident bacteria colonies in a stable, established tank should keep the ammonia and nitrites at zero at all times.

It sounds like the beneficial bacteria you added went ahead and sped up the cycling of your tank, helping to establish the first necessary bacteria, and converted your ammonia to nitrites. Now, with a little more time, the other type of bacteria will grow and start turning your nitrites into nitrates (you should start to see a spike in nitrates sometime soon I would imagine).

So, I suppose in the meantime just do very frequent water changes to keep the nitrites diluted, until they naturally drop to zero. The ammonia and nitrites are much more poisonous to fish than nitrates, as I understand it, so while the tank is still cycling (if that is indeed what is happening) try to keep the nitrites in check. Hope that helped :)

FishRCool 03-12-2008 12:39 AM

started tank Feb 5th
so if I do "frequent" water changes it won't mess up the cycle or the progress I have gotten so far? When I add water should I add more of the beneficial bacteria also?

Oh, and what is frequent?

I've read alot of stuff on how to cycle a tank....a little too late....after the fish were added like lfs said to I'm a little out of order. Thank you.

conger 03-12-2008 12:49 AM

nah, frequent water changes won't mess up the cycle. The bacteria grows on surfaces in the tank, like on the substrate and rocks, in the filter bags, and possibly even the glass walls of the tank. So the bacteria isn't really floating around in the water itself, so changing the water just dilutes the pollutants.

As far as what "frequent" means, I mean really the honest answer is it depends on your nitrite levels... if they're high, maybe even 10%-25% daily or every two days until its lower, and then as necessary to keep the nitrites low. But to be honest, I don't think it will be too long before the cycle completes, so this might not be a problem. You might be able to get away with less than what I described above, thats just the best thing you can do IMO.

And whether or not to add more bacteria as you do water changes, I'm not really sure. Maybe someone else can chime in and let us both know. All I know is that you don't NEED to... I guess it could either speed up the completion of the cycle, or it could hurt something by adding too much, I just don't know.

Oh, back in your original post, I'd suggest changing any carbon you have in your filter once a month, and then the bio-bags probably less often than that. The bio-bags or filter itself probably came with recommended filter changing times, so you could check there if you still have the boxes/instructions.

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