Swimming pools can be a problem, sometimes things occur with them and you just don’t have the answer. I’ve worked with pools, both in their construction and maintenance for nearly twenty years and, without wishing to blow my own trumpet, I am rarely stuck for a solution no matter what the problem is. I in fact regularly receive telephone calls from other gîte owners or their agents to discuss various pool problems and I am seldom stumped for an answer. All that changed though when my friend Tate phoned me up and said that he had black spots on the bottom of his pool, which were getting worse by the day, and refused to be brushed off.
As I wasn't sure what he meant I took a ride over to his place and lo and behold there they were, and true to his account no amount of scrubbing would remove them. Being at a loss to explain the problem let alone suggest a cure, I took my leave of Tate and headed back to where I knew I would find the answer. I thought it was algae, but I had no idea what algae, and what should be done about it escaped me. I decided to take the advice that one of my English neighbours had once given me. Besides running several gîtes in different areas of France, he also sells young willow plants for ornamental hedge building in his spare time. I can say that, from my horticultural days, I do know a bit about willows and knowing my neighbour Pete I knew that he almost certainly didn’t, so I asked him what he did when customers asked him for information about things concerning willows. His simple answer was I Google-it, this is a bit of information that has stuck with me and so I got straight on to the computer and Googled "black mould on swimming pools.
There were as expected hundreds of websites offering information and cures, but what I discovered was somewhat surprising. Firstly Black Spot Algae is not algae, it’s a bacteria, and secondly, and not so surprising, it is tremendously difficult to get rid of. Before I go any further I must point out that Tate’s pool is tiled and in general Black Spot Algae is only a problem for tiled pools as the bacteria cannot get a grip on liners and fibreglass. After searching many sites and even more pages it became clear that this was certainly a problem that was going to be difficult to solve. Invariably the websites said that the only way to remove the bacteria was a lot of hand scrubbing, as the bacteria gets its roots into the grouting between the tiles and then forms a hard crust on the top which is resistant to chemicals and all but the most vigorous scrubbing. I don’t know about you but on a pool that is 2 meters deep I cant envisage doing this without sub-aqua equipment and a strong back, neither of which I process.
My initial solution was to test out one of my theories, which at least stood some chance of working, as it would have been the method that I would have employed had the pool been empty. It was to use a pressure washer. Easy enough in the shallow end, but the deep end presents an altogether different scenario. Undaunted I attached the pressure gun, with duct tape, to the end of the telescopic pole that is used to brush the pool, taped the trigger in the “on” position and used the on-off button on the machine to control the operation. It worked a treat with the one exception, which was that it quickly covered the top of the water in the pool with the hard black caps of the bacteria making it difficult to see what I was doing. This meant that I had to stop once or twice to allow the skimmers to clear the caps away; it wasn’t that bad really, it was a hot sunny day, and lying by the pool in the sun chatting to Tate was, as always, a pleasure. Having finished and then cleaned the pool the filtration system needed to be thoroughly back washed and then the pool shocked with high doses of chlorine and anti bactericide.
I must emphasise that this is a quick and temporary fix, during the winter the pool will either need to be emptied to cleaned more thoroughly, which as it is a saltwater pool I’m reluctant to suggest, or it will need a stronger chemical treatment. I do have an idea what chemical to use, but if it doesn’t work I will have wasted another year and I’ll have to go through the same cleaning process during the summer. This bacterium truly is one of the most persistent and if you get it all I can say is good luck, but watch this space.
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