Its more of a foam from minerals then. If you do a 40% water change ull be almost clear. Just make sure u add "prime" or some other dechlorinater when adding tap water, also make sure the temp of the new water is relativly the same as the tanks. And if u rinse ur filter foam or media USE TANK WATER! TAP WATER KILLS BACTERIA!
id do a change tomorrow and it will be significantly better and maybe another one in exactly 5-7 days!!
What is ur setup? Fish, tank, filtration, heater, etc!
Maybe i can give u more advice.