Pool is actually 10K gallons. It's only 5'10" at the deep end. I'm guessing yours is deeper to account for the other 5,000 gallons.

I've been using the Metal Magic as well with great results. After use, I'm usually stain free for a few weeks. When the pool gets too stained for me, which is just a slight brown tinge around some of the radius, I'll put in a bottle and it clears in 2 days. My family doesn't notice the stains, but of course I do. I'm anal. I've not used a maintenance dose, but I will try it next season.

The reason why I think I'm getting stains is high Ph and high Cl. Unfortunately, I found this site late and my CYA was already 70 by using pucks. I'm on bleach now, but keep the Cl between 5 and 10 per the best guess. My Ph is pretty constant at 7.5 - I should probably lower a bit, which I know I can achieve by covering the pool a few days with solar cover. But, I know the higher PH and Cl is not good news for stains on fiberglass. But, I'm comfortable that I know the reasons why stains occur and I can easily get rid of them, so I'm not concerned. I have acid on hand in case I need it, but haven't tried it because the MM works great. I just wished it had a more lasting effect. I'll bet my situation gets better over time as the CYA reduces from evaporation and spillout and mixing with rain. I'll be able to run with less Cl. I did buy a metal test kit for Copper and Iron, but not really sure how to interpret the results. Probably a waste of money for me. Anyway, what's the deal with Calcium? How does this help? I have a test kit for that, too, but I can't remember what my results were. Since I've had the pool, I've shocked about 3 times using CalHypo.

Thanks for the offer to call about the hole. Actually, if they told me it was just cosmetic and will not get bigger, I'm okay with that. I'm really the only one that can see it. I was upset because I was not sure it could lead to something else. But, I still don't understand how a pool like this can get a hole. I don't use anything sharp.