Spotty, roungh, discolored, plaster

There are tale-tale signs of why plaster is discolored, spotty, or rough. Typically it is not because the plaster mix is bad. The reasons are usually because there is something not balanced in the water and therefore, the water is trying to balance itself. If there is not enough mineral in the water, it will actually take the mineral needed out of your plaster causing pits, discoloration, and checking. If there is too much mineral in your water, it will deposit those minerals onto your plaster finish.

A good pool professional will know "all" the tests to take to see how balanced the water is.

If the pool has gotten to a point where the plaster looks ruined, sometimes a light acid wash or acid bath can be done to prevent replastering. Multiple acid washes will eat the plaster away. Plaster older than 15 years should be replastered as a bath or wash maybe unproductive.