Pool Algae: What's up with our steps?

Factual Questions
1

We have an inground pool. The steps have been stained or dirtied with a substance that is not easily cleaned. This has been the situation ever since we bought the house out of foreclosure last year (when the pool had been rotting for an uknown period of time). The liner has since been replaced but for some reason, the pool guys who did it filled up the pool without cleaning the steps at all. So the liner is new but the steps are gross.

My husband is wondering if this stuff is “black algae.” Or maybe a combination of substances with algae and something else. It comes off in flakes when scratched but it takes some effort. It doesn’t seem to be growing at any noticably rapid pace, nor did it retreat over the winter. We can use the pool just fine, but it’s icky.

Regardless of what it is, we’re trying to figure out if scraping the stuff off while the pool is full will contaminate the water to a disasterous degree. If it’s simply a matter of doing a little extra cleaning and filtering until the crud works its way through, that’s fine. We’re hoping we don’t need to drain the pool to get them clean.

Photos:

Thanks in advance for your pearls of pool wisdom!

2

Oh, yeah - that’s “black algae.”

Concentrated shock scrubbed onto it will get rid of it for a while, but it never goes away completely.

3

Every season when I open my pool I use the Mr. Clean Magic Erasers to clean my steps. Now I don’t have stains like that, but my steps come out sparkling white.

4

Once it gets on that thick, scrubbing is necessary to remove it. You might be able to control regrowth with algicides and proper chlorination, but some amount of manual scrubbing may be beneficial on an ongoing basis. The key thing about algae growth is that it’s much easier to prevent it from starting than it is to control once it gets a foothold.

When I managed an apartment building with a pool, we took a brush and brushed down the walls and steps of the pool every day - just one swipe up and down each section to dislodge anything that might start growing. (Yeah, that was a little overkill, but the pool got a lot of use and the health department made two random inspections each summer, so we erred on the side of caution).