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Anonymous
Anonymous asked in PetsFish · 4 weeks ago

How should I interpret these water parameters?

I’ve just taken over care of a fish tank. I took the measurements and I think it’s an 18 gallon tank. It is stocked with 3 danios who are 3 years old. Hardy little fish. The filter was very old so I replaced it with a newer one. I added in a sponge from the older filter to help with the bacteria and added some Fluval biological enhancer. 

I don’t want to add any fish until I’m sure the water is fine so I used the API master test kit. I performed an 80% water change yesterday since it had been a while since the last one and I know those fish can handle it.

pH is 6.6

Ammonia 0.25ppm

Nitrite 0ppm

Nitrate 0ppm

I’ve read pH will start to rise after a water change. Is this true? It just looks low to me.

What should I do about the ammonia? It doesn’t sound right to do another water change now. I do have a fluval biological cleaner. Would that help? Or is a little bit of ammonia okay?

Sorry not the most experienced but I want to look after them well.

Update:

Just tested my tap water. It’s showing the same 0.25ppm ammonia and 6.6 pH. Hopefully my tank is still cycled and will break that ammonia down. I will keep a close eye and read up on cycling a tank with fish 

4 Answers

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  • 4 weeks ago
    Favourite answer

    Yes, like the others said, you lost the cycle.  It was probobly throughing out the old filter that did it, not the water change.  Large water changes can stress out fish, can change the temperature and other water chemistry too much for fish.  But It should not have killed the cycle.  

    You need to follow instructions for a fish in cycle. You will need to do more water changes.

    https://www.fishlore.com/NitrogenCycle.htm

    If you still have the old filter, run both filters together for 3-6 weeks.

  • kswck2
    Lv 7
    4 weeks ago

    An 80% water change has effectively de-cycled the tank and you will need to cycle it again-Never take out more than 1/3 of the water in a tank cleaning. Filters should be rinsed and reused until they either fall apart or there is a serious infestation in a tank. 

    A 'Little bit' of ammonia is Never a good thing, monitor the water while you are cycling. And when taking a water sample, take the sample from the Bottom of the tank, don't just scoop off some from the top. 

    Danios are a schooling fish, and there should be a minimum of 6-8, so that would be the next fish to add. 

    But your tank is quite small. Might be a better idea to start a larger, like a 30+ gallon tank, depending on whatever else you want to add to it. Keep in mind that Danio's swim-constantly. So they need the room to move about. 

  • Raven
    Lv 5
    4 weeks ago

    A little bit of ammonia is NOT okay. If you have ammonia the tank is not cycled. You need to look up Cycling a Tank With Fish. I think with proper care this tank will cycle fast, since it's been set up a long time. Stop doing water changes, just keep doing those tests daily. You want to see nitrite start to rise. This shows that the tank is cycling and the proper beneficial bacteria is growing. Keep up doing the tests. When your nitrite and your ammonia both drop to zero after 24 hours, the tank is cycled.

  • John
    Lv 6
    4 weeks ago

    Buy a bigger fish tank. My gf brought over a 20 gallon fish tank and put four adult Crappie's in it. Disaster!

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