# Forum Home Renovation Pools, Spa & Water Features  Black spot on side of pool- is there a gourney attachment i can use to carefully rmve

## DBR

hi guys, 
on the side of our saltwater pebblecrete pool we have black algae dots/ spots.. I have added copper to the pool (algaecide) and brush it regularly to remove,, however due to the shape of the stones - pebblecrete its hard to brush all the surface..... 
I know that  high pressure gourney would do the job awesome however I have two issues with it :Wink 1: ;;
a) I will need to be careful that I don't use so much power as to remove the stones...
b) is there an attachment that I can put on a gourney that can be used for this purpose?- Ie a long hose with a brush on the end that I can use with the gourney to remove black spot?

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## Uncle Bob

Might just need a super chlorination (shock treatment).

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## commodorenut

I'd be surprised if the pressure washer would damage it.  
I regularly pressure-clean our front & back verandahs to get rid of the black mould areas that form after long periods of being damp.
They are that early-80s pebble-crete that was popular on project homes around Sydney.  It doesn't lift any of the finish. 
You can hold the wand further away to reduce the pressure at the surface

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## ringtail

From memory the best way to deal with black spot is to stick granulated chlorine on it. Easy if it's on a step but harder if it's on the side. Chlorine just bleaches it anyway and doesn't kill it so I've read. Man I'm glad I went for a bioniser pool with tiles. Pebblecrete and blackspot seem to go hand in hand.

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## Marc

Stiff brush and granulated chlorine.otherwise a turbo nozzle.http://g04.a.alicdn.com/kf/HTB1kRNuH...r-cleaning.jpg

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## slepax

Are you positive the spots are black and not dark brownish? Could look the same but very different cause. 
The fact that you constantly add copper may result in rust spots. 
Sent from my GT-I9305 using Tapatalk

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## NRB

I would agree that adding copper may be adding to the problem,copper keeps building up and does not get diluted.
We had this problem is our pool,we had to empty our pool and acid wash it.
It looks quite different with the water out.

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