Black Mold/Algie in Tile grout of Fiberglass pool

[bbusch10]

I have had a fiberglass pool for three years now.

Around the perimeter, at the water line, I have a row of tile. This tile is attached to the pool and grouted in what appears to be white silicon caulking, or some pool friendly version of this.

I have black mold/algie in the grout/caulking around half the pool, and it seems to be getting worse each year. I have tried a bunch or different cleaning things, including bleach, but nothing seems to help.

The pool company has been no help.

Any ideas?

 

[Yakiman]

try soft scrub.

 

[bbusch10]

Thanks Dave I will try. The problem is that it is not hard grout, its soft caulk with the mold in it. Almost like mold in a shower.

 

[Yakiman]

That is one of the things we use it for. It has bleach in it.

 

[duraleigh]

Is it at, below, or above the waterline most of the time?

 

[bbusch10]

yes, it is at or below the water line, and on the side of the pool that the tile gets shade from the overhang. The water is usually in the middle of the diamond in the picture.

 

[duraleigh]

Algae grows in pools that are under-chlorinated. Once established it takes a LOT more chlorine to kill it.

Here would be my path.

1. Post a complete set of test results so we can get a picture of your pool water chemistry. Short of that, tell us how you have been chlorinating the pool and how you have tested chlorine levels.

2. Once you get a very good grip on what's required to get your pool water in shape, be prepared to over chlorinate your pool to kill the algae. I can't say how much that will be until you get us some test results. Secondly, on a daily basis, I would take a stiff bristle brush on a handle and manually scrub the black spots daily. This allows the chlorine to work far more effectively on the algae by exposing it's "innards". (sorry abouyt the redneck description).

You must plan on this taking some time and diligence and it is conceivable all of the black may not come out. The caulk was the wrong thing to use but your stuck with it for now. Perhaps this method will fix it completely or reduce it enough to make it livable.

 

[bbusch10]

Thanks Dave,
I am in Boston, so my pool is not even open yet and the water line is just below the tiles.

I was hoping I could do some scrubbing before it gets open in a couple weeks. Its a salt water pool. I add schock a couple times a year, but other then that I have not had to add anything, the water has stayed clear.

I will post a water sample in a few weeks. Do you think I can do anything before that to help?

 

[duraleigh]

Do you think I can do anything before that to help?

Well, it's hard to get your water at the proper chemistry when we don't know where it is.

Since you already applied bleach (as a cleaning solution, I guess) I think the only approach that will work is a longer term dose of bleach in your water.....we just can't effectively suggest what level that will be until you get us your test results. Be sure to include CYA, pH, TA,FC and CH so we get a really good place to start.

 

[JohnN]

I feel it should be mentioned that pool store results and test strips are not going to help much. You will need to buy a good test kit, either the TF-100 or K-2006 from tftestkits.net. It may seem expensive, but in the long run it will save you money and frustration.