Yellow water is a build up of organic matter. You need to look at your chemical, mechanical filtration, wate change schedule, feeding, and bioload. This is a basic husbandry issue symtom and you need to find and fix the problem.
Are you using carbon? The water will be clean and clear if you do and as the carbon is saturated it will not keep the water clear. Carbon needs to be changed regularly to be effecitve.
Do you have any mechanical filtration? If so you may need to do more changingcleaning of the flosspads, bio media etc.
Are you feeding more than can be eaten by the fish in about 3 minutes? If so cut down on feeding. Feed every other day.
JMO