Struggling Tank

I have had two fish tanks for about two months now. One of which is thriving and everything has been so healthy and growing great.
The other one however has had numerous problems and I’ve lost several fish from it already. I constantly test the water and nothing is explicitly wrong, 0 ammonia, nitrites, and no more than .25 ppm nitrates at the most right before water changes.
PH stays at about 6.8-7.0
Same tap water(well water) goes into both tanks after I condition it.
The plants all struggle to live as well except for one, and they fall apart so I have to remove them so they don’t pollute the water.
I have treated the water with general cute and triple sulfate twice already to try to get rid of any diseases but nothing I do seems to stick.
Only symptoms I’ve ever seen in fish was a little fin rot, if they showed symptoms at all. And most of the plants had this white cotton ball growth on their roots. I removed any affected plants.
Only fish Ive had in the tank we’re some Serpae tetras, and a few small snails that hitched a ride on some plants.
Thank you for any advice I just want to get these fish a healthy Tank without cross contamination with my thriving tank.

 

What size is the tank?
What kind of filtration do you have?
What kind of lighting?
How much water do you change and how often?
What's the tank temperature?
What kind of substrate do you have?
And an important question, what are you using to test your water?

Oh and if you could add pictures of the tank and suspected fin rot that would be helpful

 

10gallon
Simple hang on back aqueon filter
Fluorescent lighting
50% water changer per week
76-78 degreees F
Large gravel, some as big as an inch across
I use an API kit

 

10gallon
Simple hang on back aqueon filter
Fluorescent lighting
50% water changer per week
76-78 degreees F
Large gravel, some as big as an inch across
I use an API kit

What kind of plants do you have? I can't see any plants thriving in that type of gravel except for rhizome plants like anubias, java fern, and bucephalandra. Pebble type gravel has zero nutritional value for plants and root plants with smaller delicate root systems have nothing to burrow and establish roots in with gravel that size. Also how many serpaes do you have in there?

 

The plant that has survived has been an Amazon sword, I have given it root tabs occasionally, I only have 4 serpaes now I had 6 at one point. I had hornwort as well but it never takes hold, even though it’s more of a floating plant

 

The plant that has survived has been an Amazon sword, I have given it root tabs occasionally, I only have 4 serpaes now I had 6 at one point. I had hornwort as well but it never takes hold, even though it’s more of a floating plant

Yeah amazon sword in my experience only does will with substrate labelled for plants. I tried tossing some from another tank into one with very fine pebble with no nutrient value and it melted pretty quickly. I would suggest getting yourself some anubias and java fern. Super easy and hardy, very beautiful, and it doesn't need planted you can just tie it down to something. As for the fin rot, are you sure it isn't fin nipping? On the one occasion I kept serpaes they were extremely aggressive fin nippers. To the point where I took them back to the store.

 

I have never actually seen them nipping at each other and with all the attention I’ve had to give this tank I was sure that wasn’t it. And does fin nipping result in killing off others? And if it does how can I tame them to not be so aggressive

 

Hello Argent...

I can tell you that even a trace of nitrite in the tank water can be lethal to fish. You just need to commit to a more aggressive water change routine. Gradually work up to the point you remove and replace half the tank water every week. There's really no mystery about keeping a tank with healthy fish. Just change most of their water weekly. No excuses. Clean the water filtering system when you change the water and you're good to go.

Old

 

Hello Argent...

I can tell you that even a trace of nitrite in the tank water can be lethal to fish. You just need to commit to a more aggressive water change routine. Gradually work up to the point you remove and replace half the tank water every week. There's really no mystery about keeping a tank with healthy fish. Just change most of their water weekly. No excuses. Clean the water filtering system when you change the water and you're good to go.

Old

OP said NITRATES were .25 ppm....and that they also do weekly 50% water change if you would take the time to fully read the threads before replying it would be more helpful to the general forum.

OP, fin nipping does not always end in death. A lot of fish fin nip for a variety of reasons, stress, overcrowding, basic social interactions. It's part of being in their school. If you are seriously worried about fin rot, I would first try a mild medication like paraguard. It's good for parasites and fungal and bacterial infections. Super easy to dose, but you do have to remove your carbon for that.

 

Hello...

Thank you for pointing out my error. Frankly, I don't know what I'd do if I didn't have someone taking care of this for me. I believe if the poster would eliminate the chemicals from the water other than the standard water treatment and followed a consistent water change routine by removing and replacing at least half the tank water weekly, there wouldn't be a tank problem. But, this is just an educated guess on my part.

Thanks again,

Old