Staining after adding Algaecide?

[petes914]

I had some left over Algaecide I bought years ago at Costco and added 1/2 the recommended dose several weeks after opening my pool as a preventative measure. Not only did I get bubbles on the surface of the pool water but the next day noticed dark staining on my Quartz 3M plaster walls. Could the Algaecide have caused that? It seems to be fading a bit now that its been 2-3 weeks later. I took a pic of the bottle ingredients but can't seem to upload it.

All Purpose Algaecide
Alkyl (50% C14, 40% C12, 10% C16)
Dimenthyl Benzyl Ammonium Chloride 40%
Other ingredients 60%

 

[Texas Splash]

Could the Algaecide have caused that?

It is possible. I don't see a specific brand name associated with that algaecide, so I can't find it in my searches, but it's those "other ingredients" that concern me - especially if there is copper in there. Copper is a big one with algaecides. If you have some dry acid, try putting some in a sock or nylon and rub it on the area for a bit. If it lightens with dry acid, it is copper.

 

[Donldson]

There shouldn't be copper in an ammonia based algaecide. Since copper would be considered an active ingredient in algaecide it would be listed.

That doesn't mean that the staining couldn't be metallic in nature, try Pat's suggestion, but if there is copper in your water it shouldn't have come from that algaecide.