what is going on with my tank?

Hi meowfish,

It sounds as if your experiencing a bacteria bloom and when you changed your cartridge you lost all the helpful bacteria you cultivated. I would also be interested in finding out what your water readings are, but I would start with 30-40% water changes. Seems your fish are also stressing and as far as the fin damage we need to find out what happened, was the fished ever bullied by any of the tank mates as the fin damage may not be disease related.

Please tell us more so we may give you a better opinion.

Best of luck!!

With an Emp, I seriously doubt there is a problem with the bio-filter not to mention that the cartridge was changed after the cloudy water appeared, anything else changed recently. Anything you are adding to the tank, any cance the cloudy water has a green tint to it?

Try taking some water out and putting it in a clear glass, then hold tat glass next to a white sheet of paper. From here you can tell if it is A) White - a bacterial bloom or B) Greenish - an algae bloom. Starting with this info will make things a lot easier to diagnose.

"A rip in their fins"...that can be fin rot from bacteria or from a tankmate bully. As for cloudiness..I get that all the time and I also check the water, at first I got the cloudy water from my gravel from me not washing it properly, I remedied that, but still got the cloudy water..I figured maybe it's my tap water so I normally let it run cold then the hot and then let it run for about 30 seconds to a minute because of built up biofilm in the water pipes..then I fill up my bucket..oh yeah and don't forget to rinse the bucket or whatever you use to transfer water in a water change it can also harbor bacteria.....well that's how I do water transfers and now I get clear water..unless I haven't vacumed my gravel..then I get floating particles of poop Well, I'm just telling you from what I've experienced, and I'm still learning. Hope your platys are doing well

The bloom itself will not hurt the fish, but its cause may hurt the water quality. If it is greenish it is an algae bloom. This means there is too much nutrient in the tank. Feed the fish only every other day for awhile, do water changes and give the bottom a good gravel vacuum. If there are live plants int he tank like hair grass, give them a good trim. And if after a few more days things still look bad then place a black sheet over the tank for 4 days. No food or light and this generally helps clear things up.

And don't forget to reduce the amount of food going into the tank. If you have a nitrate test kits then I would make sure to check to make sure the nitrate levels stay below 10 ppm. Otherwise the algae will just be feeding off of it. And if you have no plants I would head straight for the black out for 4 days or so.

If the water is green, water changes won't make it go away (water changes are still and always will be a good idea) Do a 3-4 day blackout, and the green should die off, then keep working on the cause so it doesn't come back.
Dave