What to do if the fish tank water is muddy

Keep the acrylic fish tank away from the sun and use fish lights instead.
Change the water in the morning and evening. The amount of water pumped each time is one-fifth of the whole.
Add a filter to the Galacine fish tank. Add a water filter, it should be sold in the flower, bird, fish and insect market, not very expensive but very effective
There is a special water filter for fish farming in the market.