multiple dead fish! possible tank takedown?

[kyle6367]

Hey everyone,
So I've had a 55 gallon tank up for over a year now with a pair of jacks in it. They were doing well until I lost one from what appeared to be a bacterial infection. He had white stuff coming out of his gills, and stopped eating.
So I took the other jack back to the lfs and decided to get a bunch or community fish. Endedup with some cory cats, guppys, neons. I floated the bag for 30-40 min, and added the fish. Within hours a few were coated with a thin white film. And by the next morning all were dead! So a few days later I ended up trying a few goldfish thinking they were hearty. I just bought a few fancy tails. They were floated for half hour and I poured some tank water into the.bag. after putting them in the tank i already have one dead, and the others are developing that white coating.
I'm feeling lik I may need to take the whole thing down, clean it, and cycle again. I'd like to avoid that, but it just seems everything I add suffered the same fate. Any help would be great, thanks!

 

[jlk]

Hi! Can you tell us a bit more about your tank? Filtration/media? Cleaning schedule of media and substrate? Water change schedule (%/# a week)? Exact numbers for ammonia, nitrite, nitrate and ph? What you are using to test the water (liquid or strips)? Do you use salt or have a water softener in your home?

It does not sound like a disease issue but a serious issue with water quality. I am going to guess that ph level is extremely acidic but there may be toxin issues as well. With the introduction of numerous new fish in a very short period of time, disease also may an issue. Some more information will help!

 

[kyle6367]

Thanks for the quick reply! I'm just getting home from work so ill answer what can and get you the tanks water parameters when I can test them.
So my tank has pool filter sand for substrate, along with some rocks and plants (fake). I have 2 filters on there, one is a Rena filter do3 and the other an aquatic 30-60. They have both been up as long as thr tank has. I usually clean them alternating with each water change every 1-2 weeks.
Ill check my water and post it when I have the results. Got home to the other 2 goldfish also dead covered in a thin white coating.
And have a liquid test kit.
Here is what I got when I tested the water:
pH:6.8-7 (tap pH)
pH:6.0(tank pH)
Ammonia:0-0.25
Nitrite:0
Nitrate:5-10

Seems like somehow there was a pH crash in the tank which could be why the fish all died so quick. I just don't how it could of happened all of a sudden when there wasn't any issues for so long.