I'm pretty certain it isn't.
Some history on our pool - the pool was completed in the summer of 2003. The pool is gunite and white plaster. It is roughly about 28,000 gallons. Pool equipment is a Pentair WhisperFlo 2HP pump & Pentair DE 4048 Filter. The deep end is about 8 1/2 feet deep. For the first few years we had a neighbor that services pools and we had him taking care of it. The first few years the pool looked great, but then we started to notice yellow algae. I discussed this with him and he didn't feel it was a big deal. He dumped a few more gallons of chlorine and put a few tablets in. I had to brush it in between the weekly services, and the algae came off easily when brushed. My wife, who wasn’t working at the time, said his services consisted of 5 minutes and what she saw was him for the most part dropping tablets in a floater. She said she never saw him testing the water.
I made a decision that I would take care of the pool. I brought a water sample down to the local pool supply store and they recommended using Yellow Treat and to bump up the chlorine. This seemed to work for a period of time, but the yellow algae never really went away. About year 6 the pool place had a ah-ha moment when they tested for phosphates. The level was above 2,000 which they said was the reason we are having the yellow algae problem, we’re feeding the algae. OK, that makes sense. We were in need of repainting the rocks and redoing the slide so we waited on what they were proposing. We drained the pool, had the rocks and the slide painted, and then refilled the pool. This was done in the winter.
Towards the end of the summer, year 7 the yellow algae started to come back. The water was tested and the phosphates were above the 2,000 level. They recommended a phosphate removal product. I followed the instructions and took the filers out and cleaned them. New DE was added and then the product was dumped into the pool. Within a Ĺ hour the filter was getting plugged up and there was sediment in the bottom of the pool. I had to backwash the filter 2 times before it maintained normal pressures.
We thought this took care of it until a water sample was brought in about a month later. The phosphate level was still above 2,000. They were scratching their heads trying to figure out what’s going on. I’m given another bottle of the phosphate remover and I purchase a special cleaner for the filter grids, more chlorine, and another 25 pound bag of DE. I repeat the cleaning of the filter, but this time I soak the filter grids in this special cleaner. I put the filter back together and add DE and then the phosphate remover. Same as before, there’s sediment in the bottom of the pool and the filter plugs up quickly. Backwashed a few more times and then the pressure is normal. We leave the pump running for 24 hours again.
The yellow algae returns. I’m kind of tired of this and it’s gotten pretty expensive between the chemicals and electricity. I call a friend of mine who cleans pools. He’s not close, or I would have had him doing this. I explain what’s been going on. He’s never used this stuff, but he’s heard from others that PoolRX works on problem algae. I take a trip to the local pool store and they’ve got this stuff in stock. I follow the instructions and lower the amount of chlorine. Amazingly the yellow algae is gone and I think we go the whole summer without it coming back.
I didn’t attribute the side effects to the PoolRX at that time, but as I’m thinking about this, that quite possibly was what happened. Hang on to this thought for a little bit longer. In the winter I started to notice some stains on the white plaster. The staining was bluish green. Then I started to notice some black dots. This went on for a few years until the black dots were like a spider web effect. I included a picture. For the most part the black stuff was only in the deep end of the pool, with a little bit in the spa and some on the swim step. Brushing it, it doesn’t come off. I drained the spa and acid washed it. The black stuff came off and it hasn’t returned.
A few weeks ago I went to the pool store and they said the black stuff is probably black algae and recommended using Algatec. We dumped that in and have been brushing the pool with a metal brisle brush. It’s not coming off. I think what we have is staining from using the PoolRX. Sooo…
I have a few questions – (A few of you might be thinking, Thank God, I wondered when he’d get to this point. )
I know I need a good testing kit. Do I need to test for copper, phosphates, or anything else in addition to kit?
The filter has a slight leak at the bottom. 3 years ago I had replaced the top for a leak. 6 of my filter grids have slight tears in the filter. Do I stick with a DE filter, or go to a cartridge?
About 6, or 7 years ago the pump went out and I replaced it with the same unit. How much of a cost benefit would I get with a variable speed pump? Our area is all electric and the prices have been rising.
The staining – is there a method for determining what it is? If it is metal staining is there a method to get rid of that short of draining and acid washing the pool? We’re in year 5 of a drought and the promised El Nino hasn’t materialized. The local water company frowns on draining pools and water is costly as it's in short supply.
Thanks for hanging in this long!