So frustrated! Can’t get the water to stay clear.

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bhurbanis

Aquarium Advice Newbie
Joined
Jan 21, 2025
Messages
9
Location
Michigan
I inherited this fish from my daughter who is away at college. I’m not even really sure what kind of fish it is. 20 gallon tank and I’m running two filters that I change at least once a month. Siphon out the rocks, did 50% water change, cleaned the decor and put in freshwater. And this is what it does.

Any advice is much appreciated.
 

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It's called a biological bloom and it's bacteria consuming nutrients in the water until they grow in such numbers that they become visible.

Bacterial blooms are common in newly established aquariums, and they tend to go away on their own as your cycle establishes and the nitrogen cycle consumes these nutrients.

Is it just the fish you inherited and you got new equipment? Or did the aquarium, filters etc all come with the fish?

How often are you doing a water change and how much do you normally change?

There are 3 issues that could be the cause. And it might be a little of all 3.

  • You arent cycled. If it's a new aquarium then it needs to be cycled. If it's an established aquarium then if it was moved it may have disrupted your cycle and it needs to re-establish.
  • By "change the filter" i presume you mean change a cartridge? The microbes responsible for your cycle live inside your filtration, and every time you change anything you throw those microbes away, which again disrupts your cycle. Don't throw away cartridges unless they are literally falling apart. Just rinse them on dechlorinated water and put them back. When you absolutely have to change a cartridge, don't change them all at once. Change one, 2 weeks to a month later change another. That way you arent throwing away all those microbes and your cycle doesn't need to catch up so much.
  • Your aquarium is too small for that size fish. You really need something at least twice as big. There simply isnt enough water volume to sufficiently dilute the waste your fish produces. You haven't mentioned what filters you have, but they not be enough to filter out all the waste such a large, messy fish.
Do you have a water test kit? Can you test your water parameters?

I'm conscious you might have no understanding of what the nitrogen cycle is, or what cycling a tank means. So please let me know if I have used terms you don't understand and I can explain in more detail. But its going to be a little science lesson.

It looks like a goldfish. How big is it?
 
It's called a biological bloom and it's bacteria consuming nutrients in the water until they grow in such numbers that they become visible.

Bacterial blooms are common in newly established aquariums, and they tend to go away on their own as your cycle establishes and the nitrogen cycle consumes these nutrients.

Is it just the fish you inherited and you got new equipment? Or did the aquarium, filters etc all come with the fish?

How often are you doing a water change and how much do you normally change?

There are 3 issues that could be the cause. And it might be a little of all 3.

  • You arent cycled. If it's a new aquarium then it needs to be cycled. If it's an established aquarium then if it was moved it may have disrupted your cycle and it needs to re-establish.
  • By "change the filter" i presume you mean change a cartridge? The microbes responsible for your cycle live inside your filtration, and every time you change anything you throw those microbes away, which again disrupts your cycle. Don't throw away cartridges unless they are literally falling apart. Just rinse them on dechlorinated water and put them back. When you absolutely have to change a cartridge, don't change them all at once. Change one, 2 weeks to a month later change another. That way you arent throwing away all those microbes and your cycle doesn't need to catch up so much.
  • Your aquarium is too small for that size fish. You really need something at least twice as big. There simply isnt enough water volume to sufficiently dilute the waste your fish produces. You haven't mentioned what filters you have, but they not be enough to filter out all the waste such a large, messy fish.
Do you have a water test kit? Can you test your water parameters?

I'm conscious you might have no understanding of what the nitrogen cycle is, or what cycling a tank means. So please let me know if I have used terms you don't understand and I can explain in more detail. But its going to be a little science lesson.

It looks like a goldfish. How big is it?
I’ve had the fish for a couple years and I switched him to this 20 gallon aquarium about a year ago. And he had a growth spurt. He’s about 8 inches long. The water was perfectly clear for a while and then suddenly it’s cloudy and I can’t get it clear. I also wondered about not changing the cartridge and rinsing it off. Maybe I will try that and see how it goes.
 
If I put this fish into a bigger tank, is he going to continue to get larger? If I keep them in this tank, will he stop growing? It was an 2 inch supermarket fish 2 1/2 years ago and now he is giant! Kind of pinkish and color and he’s really cool, but I can’t continue to buy a bigger aquariums yearly.
 
It's called a biological bloom and it's bacteria consuming nutrients in the water until they grow in such numbers that they become visible.

Bacterial blooms are common in newly established aquariums, and they tend to go away on their own as your cycle establishes and the nitrogen cycle consumes these nutrients.

Is it just the fish you inherited and you got new equipment? Or did the aquarium, filters etc all come with the fish?

How often are you doing a water change and how much do you normally change?

There are 3 issues that could be the cause. And it might be a little of all 3.

  • You arent cycled. If it's a new aquarium then it needs to be cycled. If it's an established aquarium then if it was moved it may have disrupted your cycle and it needs to re-establish.
  • By "change the filter" i presume you mean change a cartridge? The microbes responsible for your cycle live inside your filtration, and every time you change anything you throw those microbes away, which again disrupts your cycle. Don't throw away cartridges unless they are literally falling apart. Just rinse them on dechlorinated water and put them back. When you absolutely have to change a cartridge, don't change them all at once. Change one, 2 weeks to a month later change another. That way you arent throwing away all those microbes and your cycle doesn't need to catch up so much.
  • Your aquarium is too small for that size fish. You really need something at least twice as big. There simply isnt enough water volume to sufficiently dilute the waste your fish produces. You haven't mentioned what filters you have, but they not be enough to filter out all the waste such a large, messy fish.
Do you have a water test kit? Can you test your water parameters?

I'm conscious you might have no understanding of what the nitrogen cycle is, or what cycling a tank means. So please let me know if I have used terms you don't understand and I can explain in more detail. But its going to be a little science lesson.

It looks like a goldfish. How big is it?
 

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It's a bit of a myth that fish grow to the size of the aquarium. What tends to happen is that fish grow to the size of the aquarium and then start to suffer ill health and die.

At 2 and half years its probably done all its growing. Potentially it could get to 12", but spending its early years in a small tank will have stunted its growth to a degree. A bigger tank might help it recover a bit, but I can't see it getting to full adult size now.

Given the aquarium has been clear before, but not anymore now the fish is bigger, I would say its just outgrown the capacity of your aquarium to dilute and filter out waste. You really need to know your water parameters to confirm this though. If you don't have a test kit take a cupful of water from the tank before your next water change and take it to an aquarium store, ask for them to test it. Write the numbers down.

Following getting the water test, you could try and compensate for the too small a tank by more frequent water changes. 50% water change 2 or 3 times per week. But the fish should really be in a bigger tank than 20 gallons. It's your fish though, and I understand not everyone has the space or budget to provide a larger aquarium. Your fish will survive in 20 gallons, probably wont live as long as it could though (10 to 20 years). Its already got to a decent size so it cant be all that bad. A 50 gallon aquarium, with filtration rated for 100 gallons would work better, be easier to maintain water quality and give your fish a much better quality of life, hopefully for another 10 years or more though.

Goldfish really belong outside in a pond, but I'm sure you are attached to it and wouldn't now want to rehome it.
 
It’s currently in a 20 gallon. Would it do any good to go up to a 40 or even 30? I could get a test kit. I assume it’s similar as the one we have for our pool. He doesn’t seem to be suffering in anyway, but I’m sure it would like more space to swim.
 
If your current aquarium is right on the limit on what it can support then a bigger aquarium should mean you can more easily manage your water quality, which should mean bacterial blooms wouldn't happen once you've cycled the new aquarium.

So yes a 30 or 40 gallon aquarium is going to help, but only if you also sort out the filtration at the same time. I would look for a filter rated for 50 gallons and make sure its set up properly. Maybe a small external canister filter like a fluval 207.

You could consider a UV steriliser in your current aquarium. It will kill off those bacteria and leave you with clear water. It's treating a symptom rather than cause, and wouldn't address your aquarium generally being on the small size, but it would address the issue you came here for.

Something like this.


Yes, an aquarium test kit is going to be similar to a pool test kit. You can get strips and liquid drop tests, liquid drop tests are going to be better and longer term more cost effective. This is the standard kit used in the hobby. It covers what you need, is fairly easy to use and read, is accurate enough for what you are using it for.


Other test kits are available, but this is the most commonly used one.
 
Thank you for all the help! When I got this fish I had no idea it was a comet and may outlive me and grow so large. I thought it would be dead in a month and I was just being nice. Haha. I decided to get a 40 gallon that I’m picking up this weekend. I’ll check out the fluval filter. I did have the water tested at a fish store near me and it was in good shape! But I also learned I’m wayyy over feeding.

Thanks again for your advice! I’m nervous to set up a new aquarium, I’ll need more rocks and plants and let it cycle. I’ll be researching this a bit more!
 
A couple of points.

Pet stores are notorious for not knowing what they are talking about. There are obviously good knowledgeable employees, and there are employees who know no more than you do.

Never let a fish store employees just tell you all the parameters are good. You have no idea if they know a good set of test results from bad. Always get them to tell you numbers and write them down. If you know enough about water quality to look at them and determine what they mean, great. If not, ask someone you know that knows what they mean.

And goldfish are different to other fish with regards to feeding. They need a lot more food. What the petstore guy tell you about how much to feed?

Essentially goldfish don't have a stomach, food goes right through them. And their food is more vegetable based, so its less nutritious. So what is commonly held to be once a day as much as they eat in 3 minutes, and a fishes stomach is the size of its eye so feed as much food to fill it's stomach just isn't true for goldfish.

Goldfish need to be fed several times a day, they poop a lot, which is why goldfish need much bigger aquariums and filtration systems than most other fish. You may not be overfeeding if the petstore guy gave you typical feeding advice based on fish other than goldfish. If you had been overfeeding then it would show in your parameters, which the guy said was good. So something doesn't tie up.
 
I’m feeding Bug Bites pellets a few times a day. They told me 4-5 pellets every day or two. That doesn’t seem to be enough. This fish literally begs when you walk near the tank.
 
See what I mean. They have probably gone through a store induction, picked up a soundbite that makes it appear they know what they are doing and pass that soundbite on, even if it might not be relevant to your particular situation.

Bug bites come in different varieties. If it's the goldfish one that's great. If not, try the goldfish one. I would look at giving some variety in the food too, something to provide a bit more vegetable matter in their diet like a spirulina flake, which bug bites also do.

I'm not really a goldfish person, I haven't kept goldfish for decades, but I would look at feeding 3 times a day as much as is eaten in 2 to 3 minutes. You don't want to leave uneaten food, so if after a couple of minutes there is lots of food left over feed less the next time. If it's all gone in a minute, feed a little extra. You should be able to figure it out.

And fish will always beg for food. As said goldfish don't really have a stomach to hold food so they are always hungry.
 
Bug bites are not the proper full time diet for a goldfish. I suggest you get foods that say they are a Goldfish Food specifically. You can find this in flakes, sticks, pellets, etc. As Aiken explained, gold fish are vegetarians more than omnivores so they have issues digesting meat proteins. While they do eat bugs, it's in conjunction with a lot of vegetable protein. That way, the meat protein is diluted into the vegetable matter. To help you visualize their needs, Panda bears only eat Bamboo. They need to eat as much as 80 lbs of bamboo a day to get the nutrition they need to survive because Bamboo is nutrient poor. That's your goldfish in a nutshell. ;) (y)
 
Bug bites are not the proper full time diet for a goldfish. I suggest you get foods that say they are a Goldfish Food specifically. You can find this in flakes, sticks, pellets, etc. As Aiken explained, gold fish are vegetarians more than omnivores so they have issues digesting meat proteins. While they do eat bugs, it's in conjunction with a lot of vegetable protein. That way, the meat protein is diluted into the vegetable matter. To help you visualize their needs, Panda bears only eat Bamboo. They need to eat as much as 80 lbs of bamboo a day to get the nutrition they need to survive because Bamboo is nutrient poor. That's your goldfish in a nutshell. ;) (y)
We’ve been feeding this. I’ve given up on the flakes because they just clutter the water.
 

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We’ve been feeding this. I’ve given up on the flakes because they just clutter the water.
Okay. As I explained, this is a new product to me as I've no seen it in the stores I've visited. You should still offer more than just the one food. If the flakes were cluttering the water, it means that you were feeding too much of them. Only feed as much as the fish can eat in 2-3 minutes. (y)
 
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