Sprayed Biocide on external brick work -

[Reyes]

Hi.

Had green algae stains on this external chimney breast. I sprayed Soluguard multi surface biocide-high strength and left for a few days. Green Algae stains have gone. Instead the bricks have changed colour to a off white colour. Is there anything i can do to get the colour back to its original?
Thankyou

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[Mr Chibs]

Can't help on the chalky looking covering, but bleach can be used for algae.

Have you tried washing off the chalky?
Scrubbing brush and water... or pressure washer.

Perhaps brick acid if all else fails.

Good luck.