I have the API freshwater kit. I tested for 0.25 ppm ammonia and 40ppm nitrate. After the water change, I have 0.50 ppm ammonia and 5ppm nitrate. WHAT THE HECK?

In fact right before I put water in and after I took 25% water out, my ammonia was 8 ppm. I cleaned the gravel, so maybe that's why the ammonia rose? But that doesn't make sense.

I treated my water before adding it with API stress-coat, which is a dechlorinator / dechloraminator and Stress Zyme, which adds bacteria. I also added Seachem Flourish for plants.

  • I did a very dumb thing.... I took all of my sand out and replaced it with NEW rocks... Ammonia is very high (8) :I When I get high (NEVER THIS HIGH) Levels I use turbostart helps a lot.
    – user6188
    Commented Nov 30, 2015 at 3:43
  • At least do it slowly @Matt
    – Don Larynx
    Commented Dec 21, 2015 at 21:45

2 Answers 2


You're changing an awful lot of variables all at once, so your readings (and your nitrogen cycle) are likely way off. Slow down a bit, and let's look at the possibilities one at a time.

First, most water treatments that neutralize ammonia work by converting the ammonia (NH3) into harmless ammonium (NH4+), which will by removed by your bio filters. The test kits can't tell the difference, giving you false positives. Similar story for chlorine and chloramine treatments. You shouldn't take water readings too shortly after making water or chemistry changes. You have to give it a day or so for the water chemistry and readings to stabilize; otherwise, you'll be chasing thrashing readings and probably making things progressively worse.

Most of the beneficial bacteria that remove these compounds lives in your filter media and your substrate. When doing your partial water changes, you should only siphon off the surface debris and only "deep clean" about a third of your gravel in any given week (max). Also, changing your filter material can cause an ammonia spike because you're throwing away the "bio" part of your bio filter which stalls your nitrogen cycle. You should only rinse your filter media in aquarium water (not replace) and only when needed. I only replace individual pieces of my filter media when it is absolutely falling apart (try not to do too much at once).

I'm not sure if you've determined that you need all those other chemicals you're adding during routine water changes, but in general… stop adding any chemicals that you don't explicitly need — i.e. you need a water conditioner but really not much else unless you have diagnosed a specific condition that needs treatment. I'm assuming your tap water is basically okay with the chemicals you are using, but you may want to take a fresh sample to your local aquarium shop for a test to see what you actually need.

  • I didn't throw away the "bio" part. I threw away the chemical part... In fact how did you know I tampered with my filter? It says it nowhere in there.
    – Don Larynx
    Commented Nov 26, 2013 at 17:42
  • 2
    @DonLarynx Lucky guess based on experience. The effect matched the cause. Get rid of the chemicals, unless you determine that you absolutely need them... and only after you've given your system a chance to stabilize biologically. I've learned that the less I did to "treat" non-existent problems, the more balanced my system became. Commented Nov 26, 2013 at 20:30
  • @DonLarynx - since Robert (correctly?) deduced that you manipulated the filter, can you please update the Question appropriately? I'm never a fan of leaving facts to grow stale in the comments.
    – JoshDM
    Commented Nov 26, 2013 at 21:07

Also make sure you are checking the tap water or whatever you’re using for ammonia before you do water changes

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