How can water parameters suddenly fall?

[Alexis22]

Hello!

I have a year old 5 gallon fish tank. 2 platys , 2 longfin danio and a little catfish type. Tank is great no issues but out of nowhere one platy started showing signs of distress. Test strip showed moderate nitrates and nitrites but not high. Did a water change last week. Platy looked great after was back to old self. But now a week later today she’s dying. Water strip is about the same read again now. I do water changes about once a month maybe every 3 weeks and use Seachem prime and stability. Have a black coarse pad filter with white fine pad in front and just change the white pad maybe every two months. Haven’t had any issues in a year since its cycled. How can suddenly I start having these issues? No other changes to the tank. 

[Gliderzz]

Nitrites (even a tiny amount) will cause issues in your tank. For a 5 gallon, weekly to bi-weekly water changes are usually recommended. By the way, what's the species of catfish? Plecos poop a lot and can easily overwhelm a 5 gallon tank with waste

Edited December 2, 2023 by Gliderzz

[Kit Craft]

If I had any nitrites in my tank, I'd do a 50% water change as soon as the test was completed. I'd test again the next day and repeat until there were zero nitrites. Just how I have always done it. 

As for nitrite spikes, I only have ever seen this when I add new fish to the tank OR if I remove filter media and reduce the bacteria level. Or if the tank is still cycling. As for why your nitrite levels spiked, I couldn't say. 

 

[Alexis22]

It’s an otocinclus. I think maybe I do need to up my water changes. Just curious if there was anything else that could be causing this. It’s funny even after a 50% water change my nitrates never reduce that much. But I know those aren’t that harmful. This is the first I’m detecting any nitrites so I think maybe just need a deep clean and more frequent changes. Thanks! 

[MrWestCoast]

I wouldn't do a "deep cleaning" at this point. Just lightly clean your substrate and do another 50% water change. Too much cleaning can cause more issues when you're already dealing with a mini cycle. Increase your water changes to 7-10 days. You'll be good to go.

[Gliderzz]

Deep cleaning can sometimes do the opposite and make things worse. I'd leave it as it is & increase water change frequency. Continue monitoring params and it should eventually stabilize 

[nabokovfan87]

On 12/2/2023 at 10:42 AM, Alexis22 said:

I do water changes about once a month maybe every 3 weeks and use Seachem prime and stability. Have a black coarse pad filter with white fine pad in front and just change the white pad maybe every two months. Haven’t had any issues in a year since its cycled. How can suddenly I start having these issues? No other changes to the tank. 

I can't speak to why in this specific case, but generally speaking for all tanks the reason parameters fall off is known as old tank syndrome.  It's a bit of a misnomer because it can happen in absolutely new tanks as well, especially when you add a lot of fish or have an active substrate pulling things out of the water.

Please be sure to watch until the end.  The second half of the video has a really key explanation of what you might be experiencing.
 

 

On 12/2/2023 at 12:21 PM, Alexis22 said:

It’s an otocinclus. I think maybe I do need to up my water changes. Just curious if there was anything else that could be causing this. It’s funny even after a 50% water change my nitrates never reduce that much. But I know those aren’t that harmful. This is the first I’m detecting any nitrites so I think maybe just need a deep clean and more frequent changes. Thanks! 

Can you show a photo of the tank?

What is the temperature and filtration like?

On 12/2/2023 at 12:25 PM, MrWestCoast said:

I wouldn't do a "deep cleaning" at this point. Just lightly clean your substrate and do another 50% water change. Too much cleaning can cause more issues when you're already dealing with a mini cycle. Increase your water changes to 7-10 days. You'll be good to go.

 

On 12/2/2023 at 1:16 PM, Gliderzz said:

Deep cleaning can sometimes do the opposite and make things worse. I'd leave it as it is & increase water change frequency. Continue monitoring params and it should eventually stabilize 

I understand the advice, but I've never.... ever ran into an issue with "deep cleaning".  Maybe the term should be thorough cleaning and making sure that you're doing a good enough job.  Moving things like the hardscape, churning the substrate to remove anaerobic pockets, checking your filtration pump and impellers, etc.  I think it's a really bad idea to try to sterilize a tank with livestock in it, but cleaning it properly has never given me issues.

[Gliderzz]

On 12/2/2023 at 5:03 PM, nabokovfan87 said:

I can't speak to why in this specific case, but generally speaking for all tanks the reason parameters fall off is known as old tank syndrome.  It's a bit of a misnomer because it can happen in absolutely new tanks as well, especially when you add a lot of fish or have an active substrate pulling things out of the water.

Please be sure to watch until the end.  The second half of the video has a really key explanation of what you might be experiencing.
 

 

Can you show a photo of the tank?

What is the temperature and filtration like?

 

I understand the advice, but I've never.... ever ran into an issue with "deep cleaning".  Maybe the term should be thorough cleaning and making sure that you're doing a good enough job.  Moving things like the hardscape, churning the substrate to remove anaerobic pockets, checking your filtration pump and impellers, etc.  I think it's a really bad idea to try to sterilize a tank with livestock in it, but cleaning it properly has never given me issues.

Personally, I have run into quite big ammonia/nitrite spikes after siphoning the gravel, moving stuff around, performing a big water change etc.

Honestly it might be a 50/50 where some people get these issues and some don't. In my personal experience, water changes are usually enough to fix the issue. But again, performing a deep cleaning may be the right thing to do for your tank.

[Biotope Biologist]

The reason is that 5 gallons of water is a small amount of water. Water changes will swing the parameters wildly as there just isnt a high enough volume to buffer said changes. I am trying to be as succinct as possible. 
 

I don’t recommend anything under 10 gallons for keeping fish for that reason as most fish produce waste quickly enough to change water parameters overnight. Smaller fish species such as rasbora and some killifish don’t produce nearly as much waste. The other thing that can also help buffer is plants. They will pull nitrate and nitrite out of the water.

 

I would say your best bet is buy a 10-20 gallon tank on sale, they are cheap this time of year, and build that out for the fish. You will have a much easier time with your current stock. Then you would also be able to increase your danio stock to 6 as they are a schooling fish and will be stressed as a pair

[Alexis22]

Great video thanks! It’s a gravel substrate. At this point I’m not looking to upgrade so I will just do more frequent changes. Also I need to order some strips from here because these tetra ones are terrible. I can’t tell if I have nitrites or not on this! The left strip is unused and looks beige still to me. This was just now after a 50% change. 

[Tlindsey]

On 12/2/2023 at 7:33 PM, Alexis22 said:

can’t tell if I have nitrites or not on this! The left strip is unused and looks beige still to me

Looks like color of caution to me. I personally like API liquid test over the strips.

[Kit Craft]

On 12/2/2023 at 8:33 PM, Tlindsey said:

Looks like color of caution to me. I personally like API liquid test over the strips.

This. I know some people like strips, but I have a very hard time reading them, regardless of brand. 

[Alexis22]

Good idea! All clear. I just also noticed my stability expired on 11/18. So maybe my tank isn’t getting the bacteria it needs with water changes! Will get a new bottle tomorrow. 

[Galabar]

The strange thing in thing with that strip reading is that the KH looks very high, whereas the GH looks very low.  I think that means that you have a lot of sodium carbonate, but very little calcium or magnesium.

[Alexis22]

If it helps at all I’m on a well with a softener and iron filter. So my waters really soft.  I was told to use reverse osmosis water for my changes but that’s just too tedious to do and my fish are used to this after a year I think 

[Kit Craft]

I wouldn't do water changes with RO. Top ups, yes. Changes, no. Unless I was remineralizing it and for me, that is more than I want to do when my water is fairly decent out of the tap (also well). 

[Lonkley]

It's probably changing because your fish have grown up and are producing more waste.

 

[Alexis22]

I’ve never really thought of that! 

[Tlindsey]

On 12/3/2023 at 1:40 PM, Lonkley said:

It's probably changing because your fish have grown up and are producing more waste.

 

Great point. 

[nabokovfan87]

On 12/2/2023 at 4:33 PM, Alexis22 said:

Also I need to order some strips from here because these tetra ones are terrible. I can’t tell if I have nitrites or not on this! The left strip is unused and looks beige still to me. This was just now after a 50% change. 

Yes you have Nitrites.  If the strips are old then that can lead to an issue, but I have almost never seen issues with nitrite or nitrate tests.

On 12/2/2023 at 9:42 PM, Alexis22 said:

If it helps at all I’m on a well with a softener and iron filter. So my waters really soft.  I was told to use reverse osmosis water for my changes but that’s just too tedious to do and my fish are used to this after a year I think 

Softeners really can mess with testing kits. Just a heads up.  It's usually best practice to get water before it runs through the softener.
 

On 12/2/2023 at 3:31 PM, Gliderzz said:

Personally, I have run into quite big ammonia/nitrite spikes after siphoning the gravel, moving stuff around, performing a big water change etc.

Honestly it might be a 50/50 where some people get these issues and some don't. In my personal experience, water changes are usually enough to fix the issue. But again, performing a deep cleaning may be the right thing to do for your tank.

I understand.  There are ways to make it more stable, but not a lot of hobbyists want to go down that avenue.  I see a lot of issues with certain types of filtration and with others I see a lot less issues.