When you say 'full water' are you meaning you use the default setting on whatever calculator you use and the default is 38% water as % of oils? If that is the case, I would say that you may be using more water than you need and that is contributing to the soda ash problem. Try changing your setting to
lye concentration or
water to lye ratio and use less water, while continuing with CPOP. This can reduce soda ash.
Depending on your recipe, of course, I would suggest moving to a 30 to 33% Lye Concentration. Perhaps you could share the specific recipe to help with trouble shooting. But for the sake of presenting you with an example of how that is done, here is a Castile soap recipe (500 grams of oils) showing the different amounts of water for 3 different settings:
Default 38% water to oil = 25.3% Lye Concentrtion = 2.9 : 1 Liquid to Lye ratio. That's a lot of water.
Try this: Change the setting to Lye Concentration & set it at, say 32%. Notice the difference in the amount of water used when that is the only change?
Or try 2:1 Water to Lye Ratio. Again, this alters the amount of water used.
Many soapmakers who prefer to use either Lye Concentration or Liquid : Lye ratio as their usual setting, in order to get more consistent results across different soap recipes.
There are several threads here at SMF that explain how soda ash forms, so I won't go into that. A search can pull up results to give you a lot more detail of the how & why of soda ash. This is just to show you a method that will help you get consistent results by using less water in your recipe.
Some also find spraying alcohol on top of the soap prior to covering it, but others don't like the pitting on top of the soap that they get with the alcohol droplets. A very fine misting sprayer can be a way to prevent the pitting, but even without spraying alcohol, reducing water in the recipe goes a long way to preventing soda ash.