One question I would ask is did you use a stain and scale control product? Its possible that you have iron in your water. I would suggest having your water tested. You should establish confidence in your source water first, including the hose 😁
Also , it is not uncommon for new spas to come contaminated from the factory . While I have not experienced this myself, there have been issues with white colored flakes appearing in new spas as a byproduct of a lubricant used in the plumbing assembly process . I dont think this is what you are describing.
Another possibility is that your spa was delivered contaminated with biofilm as a consequence of wet testing at the factory and subsequent storage and delivery processes that allow these organisms to grow
This was precisely the case with my spa although i did not see what you describe at first fill. But my spa did come contaminated I'm not making this up (i have a hot springs spa as well). While biofilm contamination often is not visible without using a product designed to release them I suppose this could be responsible for the material you are seeing. I have some reluctance to jump to this conclusion but also caution you not to rule it out
In any case it would not surprise me at all that a new spa would be delivered contaminated with something that start up chemicals would release. If you have exonerated your source water and you determine that the spa itself is contaminated You have two options as i see it
1. If you trust your dealer you could attempt to hold them responsible and compel them to correct this. The likelihood of real success is very low however, unless you have an unusually responsible dealer. I have personally had conversations with Watkins manufacturing on this topic and find that they have their head in the sand. They make a great spa but they believe that their wet testing is is flawless and all such contamination at the customer startup should be treated as a rare occurrence.
2. You could take over responsibility and do a deep cleaning purge on your spa. This is the approach I took when my grandee was delivered contaminated. I have since performed a great number of experiments and can help you through this process should you choose this route. Its really quite simple-- you can find a great deal of confidence in other forums for a product known as "ahh-some" which is intended for this purpose and which I have extensively tested. This is the stuff I used to correct the contamination in my own grandee .
Start with source water analysis and go from there
