Hello, so this is my uncle’s aquarium, he has had it for a few years I think. As you can see the water quality and all is not the greatest. I don’t really blame him for this as this aquarium didn’t originally belonged to him but his ex girlfriend who left it by him when they broke u. I promised to help him, and I have. I clean his aquarium every few weeks but thanks to the goldfish it gets pretty dirty quickly and so that isn’t enough. Sadly I can’t help him more often because of school and other stuff. Now in the last few months two goldfish have passed away. So it’s not super overstocked anymore thanks to that. And my uncle has been doing a lot of water changes because I noticed his goldfish we’re showing signs of ammonia poisoning. Now I’ve just tested the water and everything seemed good. Ammonia and nitrite were 0 and nitrate was around 25. His ph was on the low side but I don’t think goldfish react to that badly (correct me if I’m wrong I myself don’t keep goldfish). But still the fish show signs of ammonia poisoning and the water looks dirty. Is there any way to improve this? Any sort of advice would be really appreciate!