A beautiful fish indeed. A couple of things here. First, Prime detoxifies ammonia but this is not permanent; Seachem says it lasts 36 hours, then the "ammonia" becomes toxic again--but this depends. In acidic water (pH below 7) ammonia is largely ammonium which is harmless. In basic water (pH above 7) the bacteria and plants will be able to easily handle the "ammonia" after 24+ hours.
The 0.25 ppm ammonia may be due to the chloramine if this is added to your water (in California it might be). Live plants (which need ammonia/ammonium as their nitrogen source) and nitrifying bacteria will take up toxic ammonia or ammonium, whichever is present.
In other words, there is nothing to worry about.
BTW, welcome to TFF. I've no idea as to your level of knowledge on this fish, but in case you do not know, this fish is a colour form developed from the natural species
Mikrogeophagus ramirezi, and this fish (in any variety) must have warmth. A temperature in the 82-86F/28-30C range is mandatory. Not all tropical fish can manage this high a temperature long-term, so be careful with tankmates if any are intended. There are some lovely small characins that are good here, but many are not.
And floating plants like Water Sprite or Frogbit woould be well appreciated by the fish, and help you with water quality.