Tap water testing positive for ammonia - The Planted Tank Forum
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post #1 of 9 (permalink) Old 05-29-2014, 04:56 PM Thread Starter
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Tap water testing positive for ammonia


Sorry if this was covered elsewhere but I could not find a good answer after searching last night.
My 12 gallon tank has been running for 2 weeks about, now and I'm still testing 0.50 ppm ammonia. This concerned me, so I tested again; the tank, water from the tap, and water treated with prime. They all turned out exactly the same at ~0.50 ppm ammonia. My fish and shrimp seem to be doing fine, showing nothing in the way of distress. Somewhere my girlfriend found that chloramines can give a false positive with ammonium testing out as ammonia, but shouldn't prime detoxify that as well?
I'm pretty perplexed about this and was wondering if anyone had any thoughts?
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post #2 of 9 (permalink) Old 05-29-2014, 05:00 PM
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Your test kit may be innaccurate. Can always get some distilled water and test it; if it tests above 0ppm you know your test is inaccurate.

Try taking a small bit of your water to the LFS and ask them if they can test it, mine do it for free and it'll give you at least a bit more answers.
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post #3 of 9 (permalink) Old 05-29-2014, 05:02 PM Thread Starter
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For testing I am using the API freshwater master kit, and I have been performing 10-25% water changes ~ every day or two as the water quality has a ways to go still.
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post #4 of 9 (permalink) Old 05-29-2014, 05:09 PM
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Prime bonds with ammonia to create ammonium, a far less hazardous compound that still tends to be read as ammonia on test kits...prime is infamous for fooling ammonia test kits.
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post #5 of 9 (permalink) Old 05-29-2014, 05:18 PM
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Originally Posted by Grah the great View Post
Prime bonds with ammonia to create ammonium, a far less hazardous compound that still tends to be read as ammonia on test kits...prime is infamous for fooling ammonia test kits.
+ on that.

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post #6 of 9 (permalink) Old 05-29-2014, 05:26 PM Thread Starter
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That makes sense, I'm going to head over to the lfs to test my water there, what bugs me though is that the untreated tap water came up the same as water treated with prime and the cycling tank, all run simultaneously.
I checked as well, the test kit is not expired.

update- tested my water at the lfs, and my tap water showed 0.25 ppm ammonia there as well. Weird. How should I go about treating this? Should I just keep up with frequent water changes and let the cycling process take care of it with time?

Last edited by singlemind; 05-29-2014 at 06:24 PM. Reason: update
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post #7 of 9 (permalink) Old 05-29-2014, 06:27 PM
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Likely monochloramine. Based upon my unscientific research, it goes like this:

Test tap water is positive for ammonia (because it is detecting the ammonia molecules that are part of the monochloramine). Then when you use the de-chlorinator, it separates the chlorine and destroys it (possibly by converting it into cl2(g) - not too sure on that one but nonetheless) in the same way as if it was just chlorine but then the ammonia molecules remain (may be NH3 or NH4). The test kit at that point detects basically the same amount of ammonia because none has been removed.

I found this out when my tap tested positive for ammonia. It made doing a fish-in cycle seem less practical because you're always adding ammonia. Prime says it 'locks' the ammonia away from the fish so I always use that during water changes rather than regular dechlorinator. In my tap it seems to be a pretty low concentration at about .25 ppm but unless something else is there to remove it (bacteria colony or special filter media), it just goes up with the addition of fish and other waste.

Using products to clean out the ammonia seemed like it would 'starve' the cycle I was trying to build by taking out the fish waste also and leaving no ammonia.

I guess if you are doing fishless, consider it another (secondary - .25 is low) source of ammonia, once you have a cycle, the ammonia added by water changes with tap water will be eaten by the bacteria very quickly during the Prime 'lock' phase. I think 'ammo lock' does the same thing. The trick to this is, however, to have a cycle already going.

If you are doing a fish-in cycle (as you said you were), you might consider using a separate filter in a bucket where you can use ammonia absorbing media in the filter and filter the tap water after conditioning it but before adding it to the tank. Or use that media on the main tank after water changes to reduce the amount of ammonia but remove the media soon so that the ammonia doesn't bottom out before the tank has cycled. That way you could keep your levels low while you fish-in cycle.

It looks like you are at 4ppm monochloramine as of 2010 but I don't know what ppm that translates to of ammonia after you have treated the water with conditioner. I suppose it also depends on how much ammonia you are detecting. EDIT - oh, .25 from LFS. OK, that's not that high. You certainly shouldn't need to treat it specially before partial water change once the tank is cycled (use Prime of course). As noted above, there are a few choices in the interim. My bet is that LFS will find ammonia in your tap water as well. edit - looks like yea they did.

Prime says it de-toxifies the ammonia, meaning that it is not toxic to the fish while it is 'locked' - but it is somehow still there and the test kit will pick it up if it is testing for NH3 and NH4. So its not a false positive, its positive for a NH compound that Seachem Prime says is 'detoxified' not 'gone.'

Also, I have had very good luck recently with both API QuickStart and Tetra SafeStart (check expiration label) to jump start the cycle. People will say it works or it wastes your money but I haven't seen anyone say it is hurtful to the livestock so make your own choice. You probably can't use it to have an established aquarium in one day appear just by pouring in 3 ml of milky looking chemies, however, it sure seemed to push my cycle along when also trying to do the other things right at the same time (and failing at some).

-sorry for all the ninja edits there

Last edited by eisBear; 05-29-2014 at 06:56 PM. Reason: clarify last paragraph
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post #8 of 9 (permalink) Old 05-29-2014, 07:42 PM
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You could try the Seachem Multitest:Ammonia, which says that it has separate tests in the box for both free & total ammonia. I haven't tried mine yet, but read on the forum that it can measure the toxic ammonia vs. the safer bound form. I will be using mine soon to fish less cycle my new tank.

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post #9 of 9 (permalink) Old 05-30-2014, 03:02 AM
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My tap water will test 1 ppm ammonia because of the chloramine (usually the water company maintains 1 ppm chloramine), but dechlor works just fine, protecting the fish. I use Chloramine Buster or Prime.
Within a day the test shows no ammonia because the plants, bacteria or both are using it all.
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