20 Gallon Tank Cycled tank...uncycling??

je0409

I've had my 20 gallon tank set up for about 4 months and it was cycled and has had a male betta and five snails living in it for about three months (since the tank was fully cycled). I've been having a problem with green water, and I was doing frequent large water changes (about 50%- 75% once a week) trying to get rid of it. Well, I tested my tank just now for the first time in a few weeks (irresponsible on my part I know) and now my tank is reading at 0 ppm nitrates, 0 ppm nitrites, and 0.25 ppm ammonia. I have a prefilter sponge and biomax in my filter that havent been changed or washed which should have BB so I don't know why my cycle was broken. Does anyone know what happened and what I should do to fix it?
 

mattgirl

I've had my 20 gallon tank set up for about 4 months and it was cycled and has had a male betta and five snails living in it for about three months (since the tank was fully cycled). I've been having a problem with green water, and I was doing frequent large water changes (about 50%- 75% once a week) trying to get rid of it. Well, I tested my tank just now for the first time in a few weeks (irresponsible on my part I know) and now my tank is reading at 0 ppm nitrates, 0 ppm nitrites, and 0.25 ppm ammonia. I have a prefilter sponge and biomax in my filter that havent been changed or washed which should have BB so I don't know why my cycle was broken. Does anyone know what happened and what I should do to fix it?
What kind of snails? Some produce a lot of waste thus more ammonia. Some have a very low bio-load. 5 snails with a low bio-load along with a Betta in a 20 gallon tank won't have fed and grown a lot of bacteria. The amount of bacteria depends on the bio-load in the tank.

The lower the bio-load the less nitrates there will be in the tank. The large water changes may very well be why you are not seeing any nitrates. If you've not been keeping an eye on the numbers you can't know if what you are seeing is normal for this tank. I wouldn't be overly concerned if I saw .25 ammonia. It could simply be the time of day you tested. Maybe you had just fed your water pets.

Unless you constantly see this or if it starts rising I wouldn't do anything to try to fix it. Often trying to fix something that may not be broken can cause more harm than good.

If you've not over cleaned the inside of the tank and haven't scrubbed your sponge or bio-media, if all you've done is water changes and you added your water conditioner with each water change then the bacteria that has grown in the tank should still be there.
 
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carsonsgjs

If its heavily planted they may also be soaking up any nitrates in there too.
 
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je0409

I checked it two days ago and today with no water change in between and both times it read .25 ppm. I have three mystery snails and two nerite snails. I also have four plants and three moss balls in there. I haven't cleaned anything besides vaccuming the gravel when I do water changes. Should I just not worry about it?
 
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mattgirl

I checked it two days ago and today with no water change in between and both times it read .25 ppm. I have three mystery snails and two nerite snails. I also have four plants and three moss balls in there. I haven't cleaned anything besides vaccuming the gravel when I do water changes. Should I just not worry about it?
Have you ever gotten a true zero reading for ammonia? It seems some folks never do when using the API liquid ammonia test. Do you shake the ammonia testing solution bottles before each use? Some folks don't and once they do they get a more accurate reading.

The same question about the nitrate test. Are you shaking bottle number 2 like your life depended on it? and then shaking the test tube for a full minute before letting it set for 5 minutes? If so then I have to think the low bio-load, water changes and your plants are why you are seeing no nitrates.

To be perfectly honest I am normally not concerned about seeing no nitrates when we know the tank is cycled. As long as there is little to no ammonia and no nitrites then I am not overly concerned. Just keep an eye on the numbers for ammonia and nitrites.

Your green water may be an algae bloom. Quite often water changes alone are not going to remove it. Something is causing it. Have you started a thread about it so those that can help with it will see the thread and will come in to help. The only thing I can think of that has been recommended is using a UV Sterilizer.
 
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Dechi

Have you tested your tap water for ammonia ?
 
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je0409

Have you ever gotten a true zero reading for ammonia? It seems some folks never do when using the API liquid ammonia test. Do you shake the ammonia testing solution bottles before each use? Some folks don't and once they do they get a more accurate reading.

The same question about the nitrate test. Are you shaking bottle number 2 like your life depended on it? and then shaking the test tube for a full minute before letting it set for 5 minutes? If so then I have to think the low bio-load, water changes and your plants are why you are seeing no nitrates.

To be perfectly honest I am normally not concerned about seeing no nitrates when we know the tank is cycled. As long as there is little to no ammonia and no nitrites then I am not overly concerned. Just keep an eye on the numbers for ammonia and nitrites.

Your green water may be an algae bloom. Quite often water changes alone are not going to remove it. Something is causing it. Have you started a thread about it so those that can help with it will see the thread and will come in to help. The only thing I can think of that has been recommended is using a UV Sterilizer.
I do believe I had a true 0 reading of ammonia to begin with. I was being pretty deligent about following the instructions with the test and watched it go from high ammonia to no ammonia (along with the appropriate changes in nitrites and nitrates) while it was cycling and it stayed at 0 for a few months. It was just during my time trying to get rid of the green water that I forgot to do regular readings for about three weeks. Also someone recommended a UV sterilizer to me not too long ago and now that I have a green killing machine, my tank is crystal! I guess I'll just keep an eye on it and, if the ammonia doesn't get too high, I'll just hope it balances itself back out :)
 
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mattgirl

I do believe I had a true 0 reading of ammonia to begin with. I was being pretty deligent about following the instructions with the test and watched it go from high ammonia to no ammonia (along with the appropriate changes in nitrites and nitrates) while it was cycling and it stayed at 0 for a few months. It was just during my time trying to get rid of the green water that I forgot to do regular readings for about three weeks. Also someone recommended a UV sterilizer to me not too long ago and now that I have a green killing machine, my tank is crystal! I guess I'll just keep an eye on it and, if the ammonia doesn't get too high, I'll just hope it balances itself back out :)
Now that the green water is taken care of I would just stick with my 50% weekly water changes. As long as the ammonia goes no higher than the slight tint of green you are seeing I would just let the tank work it out. Eventually you will start seeing nitrates again but the 50% water changes should keep it down low. As I said before. I wouldn't be overly concerned about no nitrates. As long as we know a tank is cycled and are seeing no ammonia or nitrites I see no cause for alarm.
 
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