To try to get to the bottom of the issue, it all starts at the beginning.

Was the pool properly cleaned and prepped prior to plaster application?

Were the weather conditions acceptable to apply the plaster?

Did the plaster contractor add too much calcium to the plaster mix? There is a suggested limit to the amount of calcium added to a plaster mix to help speed up curing.

Was the pool filled immediately after plastering? We always truck water in after plastering to fill it as fast as possible. Water is part of the curing process. A sequestering agent must be added during the fill as well.

With the immediate fill, we can start the filtration system immediately.

Was the water chemistry checked and balanced upon filling? Daily testing in the AM and PM is critical. This should be carefully monitored and adjusted for a 2 week period. The first few days are super critical. Your fill water whether from a truck or from your house should be tested also. You need to know what your putting into your pool so you can prepare the proper chemical balance.

Was the pool brushed twice per day for 2 weeks?

Automatic cleaners and wheeled concrete vacuums should not be used for at least 2 weeks. A vinyl vac head with brushes should be used to vacuum debris.

Salt should not be added for at least 30 days post plaster. If you can go longer without salt, it's even better.

Salt systems are great, but they require close monitoring of pH and Total Alkalinity levels as they creep up. A weekly addition of a sequestering agent is recommended and there are types designed for pools with salt systems.

The water testing does not stop after the 2 week period. The more you can test, the better handle you can get on the balancing.

The acid wash may clear some of the mottling. Too strong a solution can etch the surface and make it rough.

If the pool company can assure you in writing, the plaster will be ok after an acid wash and they will take responsibility, then go for it. You stated they have done this hundreds of times. Sometimes the issue you have will slowly clear up.

We usually handle the start up for our clients. The water chemistry is tested 2 times a day and adjusted for 2 weeks. We also record our test results.

If a customer is dead set on doing the start up, I encourage them to use this method.

Adding chemicals for adjusting must be performed a certain way. For instance, muriatic acid must be diluted in bucket of pool water and added to the pool in small increments. Pouring a gallon of acid directly into the pool, especially walking the perimeter, will damage the plaster.

Thank you so much for your thorough, knowledgeable response!

On Dec 14 2023 I have a new pool finish wetedge indigo blue. Within 5 days I notice discoloration. I don't know ifif it's

mottling. What was the outcome? Did you get it fix