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Anna, Pet Expert/Biologist
Category: Pet
Satisfied Customers: 11513
Experience:  40 yrs.: herps, pocket pets, rabbits, poultry, dogs, horses. Biology degree. Vet assistant.
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i am having trouble with my aquarium. The ammonia and the PH

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i am having trouble with my aquarium. The ammonia and the PH have been high. The ammonia is 1-1.5 and the PH is 7.4. Yesterday I did a 25% water change. Today it was still high so I did another water change and I added some PH down and rinsed the carbon filter with tank water as thats what the pet shop said to try. The PH is now 7.2. My last water change I did a gravel vac so its not the gravel. The tank is not over crowded and the tank has been set up for ages so its not a new tank. The nitrite is 0 and the nitrates are fine. I am going away tomorrow so i want to try and get things sorted. A few weeks ago I used melgafix in the tank as my fish had cloudy eyes and some missing scales.
Do I add some more PH down tomorrow?

Hello and welcome back to JustAnswer. I just reading your previous questions about the aquarium and see that this has been an ongoing problem. Some clarification will help me figure out the best way to help.

I see that you have a black moor in the tank. How big is he from mouth to tail tip?

Are there other fish in the tank? If so, what?

How big is the tank in liters or gallons?

You said in this question that the tank has been set up for ages, but in December 2012, you said you emptied and refilled it. Is this the same tank?

What is the pH of your water as it comes straight from the tap?

Thank you.


Customer: replied 4 years ago.
Hi I am not quite sure how big he is probably 4 inches he is quite large he's the only one in the tank. It's a 40 litre tank. Not sure of the ph when it comes out of the tap I always add stress coat to the tank. The tank has been set up for a few months? It was a second hand one that had fish in it before they petshop said to leave it running set up which I did and they said I could add the fish straight away as that's how the cycle can start once he's in it? I used the same carbon and rocks from his old tank. The tank has been good for a while now just every now and then the ph plays up. The ammonia has only been high for a few days. It's just the ph. Nitrite and nitrates have been good also.

Thank you for getting back to me. Don't worry about the pH. I'm not sure who told you it was a problem, but a black moor is a variety of goldfish, and they do best with a pH of at least 7.2, and higher cna be better yet. If the pH drops below 7.0, that alone can make a goldfish sick. If it goes to 6 or below, it is likely to be fatal. Different kinds of fish have different pH requirements, and we can't assume that all fish need the slightly acidic water that some of the tropical rain forest species do. Yet, that's what many pet store staff believe. So, absolutely do not add any more pH down, and leave the pH alone. The more you try to change it, the worse for your fish. You can confirm this information on pH on the following reputable goldfish sites:

The ammonia is another story. As little as 0.01 ppm can cause illness under the right circumstances. Goldfish need ammonia at zero. The biggest problem is that a 40 liter tank is too small for a goldfish this size, and you will always have trouble maintaining water quality. Goldfish produce a tremendous amount of waste, and your tank has probably not been able to cycle properly because of that. It used to be recommended to have about 4 liters of water per inch of fish. That still holds true for tropical fish, but not for goldfish. I find they do best with about 100 liters per fish, regardless of size. I’ll share my own experience with 12 inches total of goldfish (3 fish). They are in a 90 gallon (about 340 liters) tank. I have an undergravel filter, a hanging filter, and a powerful canister filter. It takes all three of those filters to maintain perfect water quality. Regardless of tank size, frequent water testing and changing is needed. Goldfish tank size is another area where pet store personnel give out incorrect information. They may not know, or they may simply want to sell more fish.

In your present tank, you'll probably need to do a weekly water change of 25% or twice a week water changes of 10% to keep the ammonia down. That may not be enough. Frequent testing will let you know. If you get a bigger tank, don't follow the pet store advice of putting a large goldfish in anew tank to cycle it. That kind of advice is outdated and is only likely to result in a sick or dead fish. We now usually cycle tanks without fish. There are other ways to cycle a tank. The following website gives detailed instructions and also explains cycling in depth.

You'll have to make up your own mind on what to do about the ammonia, but I recommend you throw away the pH Down. It is bad for your fish. If you have more questions, let me know by clicking on REPLY. I hope you'll be able to get everything under control and your fish will thrive.


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Customer: replied 4 years ago.
Thank you Anna you help has been great you get so much different advice from pet shops. I will be throwing that ph stuff down they told me it should always be 7. I will nor be adding anymore
Ph down. I always do weekly water changes now of 25% and have started gravel vac the same time. In my tank I have a filter and an airstone would a extra filter help for now until I can get a larger tank. They also told me a 40 litre is fine. Just another question how often should you change the carbon cartridge is every few months right? When it gets messy is it
Ok to give it a rinse using tank water? I don't think I will get any more
Advice from the pet shops anymore I think they cause more trouble then help thanks for all that advise I really appreciate it
I should have asked you first.
You're welcome. Yes, we see people with sick pets every day because of advice given by pet stores. Somehow , these people get it in their heads that fish need 'neutral' water at 7.0, when in reality, what different species need varies a great deal.

A second filter would help for now. I change my carbon cartridges once per month. with goldfish, they don't last as long as they will with small tropical fish. Rinsing them off helps remove the physical particles that are trapped in it, but the carbon also removes harmful gases and chemicals. It can only do that for so long, until it's capacity is used up.

I hope you don't have any more trouble.


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