Black Algae in Fiberglass Pool

by Phyllis
(California)

All of the web sites I have read tell me to use a steel wire brush first prior to treatment. I have a fiberglass pool and am afraid that if I use a wire brush I will be scratching my smooth surface and setting it up with microscopic grooves that will give black algae and even rougher surface to lock on to.

Is there something besides a wire brush I can use on a long pole?

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Hi Phyllis. I would be highly suspicious if your fiberglass pool had black algae. This kind of algae has roots that need to dig into the surface. Fiberglass is very smooth and really doesn't offer the black algae an optimal surface to grow and reproduce. If you have tile and grout around the pool you can get black algae in that area.

My first question would be how was it determined that you had black algae? Next, I would ask if you're using a copper based algaecide, are on well water, or have metals in your water source. You might have metal stains that can mimic black algae.

If you truly have black algae on your fiberglass pool, a wire brush will scratch the surface. However, you need to knock the heads off. You can try steel wool or a razor blade on the affected areas. Anything more than that will scratch the gel coating.

Next is to gently scrub the areas with a chlorine tab. This must be done to get the roots and kill them, as best you can.

I would first test to confirm your pool has black algae before doing anything else.

Robert