Every 36 hours? That is quite often.
One cause could be that you are feeding your goldpish (sorry:-) FAR too much. Feed only as much as would fit on the fish's eye daily, if it is in a heated room perhaps twice as much. Watch it when you feed. The fish should eat it all in 5 minutes. The surplus food is turning the water into a bacterial soup overnight.
Is the bowl shielded from the sun??? It is amazing how quickly the water will discolour in the sun.
To add to shaneystar2's commend. A normal fish tank is much preferred. The traditional goldfish bowl is the worst environment you could keep a fish in. It is the surface area that counts in the oxygen exchange with the air. A pump/filter is even better, but filters are not miracle implements. Their fucntion is in addition to good fishkeeping, not instead of.