Just buy some super ich cure or some kind of medication that specifically kills ich and dose the whole tank, since you said your tank got wiped out I would just over dose the entire tank and leave it running without filter cartridges/Media for a week and then do a few 50% water changes everyday...
I’m not exactly sure on the gallon size but I’m assuming it’s closer to 35 gallon. Also I got lucky with the lighting usually the tank light is too bright to get a good picture but that day it was a clear day and the sunlight helped dim the camera lol
Have you discovered exactly where the leak is? If not you should drain the tank dry it inside and out, then look for any obvious signs of cracks or loose seals if non are noticed start filling it up slowly and watch for leaks.
I don’t usually have time to use old water or to treat the water I’m rinsing media with so I’ve always used tap water to rinse with no problems.
What I do is I have a 5gal bucket or two and fill that up with tap water then I shake and scrub the media of all tanks in the same bucket considering...
Looks like Hair Algae to me. One way I know that could work would be to cut down on the lighting so keep the lights off completely for a few weeks possibly would make the algae die off.
Or a Siamese Algae Eater could take care of that.
Idk but I’ve done some inspections and it’s basically infested with them.. they’ve began eating my live plants putting holes all over them and have nearly eaten the entire Lilly pad that we had growing.
Lol I just want them gone before my plants are