I've had pools my whole life, not an expert, but know enough to be dangerous at times and accidentally fix stuff at times. I guess everyone gets lucky from time to time.
I converted from a cholrine system to a salt water system (Aqua Rite) about 4 months ago. I've always had light colored yellow algae blooms at times...easily removing them with a brush or shock treatments. When I made the coversion from cholrine all of my algae problems seemed to have stopped, which was a relief to me.
About 5 weeks ago we had 12 or so swimmers in our pool over a couple of days. I also noticed the next day that some algae blooms were growing in the pool. Well, I decided to shock it with high grade shock like I always have, but had never shocked it with the salt water system in place. I threw my shock in and before it hit the bottom of the pool the shock turned black and everywhere it hit stained my pool black.
Yes, it flat out stained my beautiful, clean pool. Everywhere the shock ran, it turned my plaster black. I tried to brush it out with a couple of different brushes and it did not work. The stain obviously was so deep it would not come off. Well, I started looking around online and noticed Vitamin C might remove the stains that the SHOCK caused.
I took a few tablets of Vitamin C and crushed them up and put it in a sock with a rock and placed it over an area of black stain. Within 3 seconds the stains are coming off. So, I roll the sock around the shallow end and everywhere it touches the stain is lifting. That's when the light bulb in my head clicked on.
So, I decided to put Vitamin C tablets all over my pool and let them disolve at the bottom. I turned on my polaris about 30 minutes later and stirred it all over my pool and 90% of the stains came out in just a few hours. The next morning I got up to see that I still had some black areas in my shallow end so I threw a few more Vitamin C tablets on the spots to treat them. These spots were located in the area of my pool where there is a sudden drop off. The tablets started to roll to my deep end and along the way(you will not believe this) turning my pool black again everywhere they ran (like fingers reaching out).
The very Vitamin C that cured my pool of the stains 24 hours earlier turned my pool black again in seconds. I decided I'd throw shock in my pool again to see if it would oxidize the stains and sure enough the shock worked. Remember, the shock is initially what caused my pool to stain black. I ran my polaris for about a week (6-8 hours a day) and the stains lifted, or most of them.
The shock stains my pool black, the vitamin C cured it. The next day Vitamin C stains my pool and the shock cures it. What is good for my pool one day is bad the next. Yes, my pool has it's own personality. I had my water tested for metals the day it happened and no metals were found in my water. I had my water tested the next day as well and no metals were found. I had my weekly chemical check twice that week and everything was exact. All the levels were right on with a healthy pool and still are today.
Needless to say, my pool has never been the same since my unfortunate event. There is still light black staining on my walls in the shallow end. The staining is getting worse and starting to spread again in the shallow end. I tried the Vitamin C tablet on my steps in the the pool and it turned black on contact and everywhere the powder rolled turned black, too. Went up to the pool store and had my water tested and everything was fine (no metals in my water).
This is where I am at as my pool stains black again:
#1. Vitamin C (stain remover) same thing turns my pool black.
#2. Shock turns my pool black.
#3. Now, some of my walls are turing bluish greem and spreading with the black stains.
My pool supplier has never heard of such a thing. My pool man has never seen or heard of anything like, but admit anything is possible. No one can tell me how to get rid of the stains or what is causing them. I really feel I deal with some credible people that are at a loss as to why this is happening. Can anyone out there tell what in the heck is happening to my pool and how an oxidizer stained my pool black and WHY what's good for my pool one day is bad the next? I'm scared to put anything in my pool to cure the problem. My water is crystal clear.....thank goodness!
No iron or copper has been found. No one has used any fertilizer in my area. I know I've talked in circles. I'm trying to work and deal with clients. Sorry, for the butchered message.
Thanks in advance!