We have a concrete pond with fish, and the concrete liner that is exposed to 
the air has some black algae stains from when the water level used to be 
higher.  The new permanent water level is below the stain.  What would be 
the easiest way to clean the dried black algae without killing the fish? 
For example bleach would be great for cleaning a white surface, except I 
think that would kill everything. 

On May 4, 7:27=A0pm, "scorpster"  wrote:
> We have a concrete pond with fish, and the concrete liner that is exposed=
 to
> the air has some black algae stains from when the water level used to be
> higher. =A0The new permanent water level is below the stain. =A0What woul=
d be
> the easiest way to clean the dried black algae without killing the fish?
> For example bleach would be great for cleaning a white surface, except I
> think that would kill everything.

rub with sand

"scorpster" <s...@ge.com> wrote in
news:ZRKLl.28573$y...@nlpi068.nbdc.sbc.com: 

> We have a concrete pond with fish, and the concrete liner that is
> exposed to the air has some black algae stains from when the water
> level used to be higher.  The new permanent water level is below the
> stain.  What would be the easiest way to clean the dried black algae
> without killing the fish? For example bleach would be great for
> cleaning a white surface, except I think that would kill everything. 
> 

Pressure washer.

On May 4, 9:25=EF=BF=BDpm, Red Green  wrote:
> "scorpster"  wrote innews:ZRKLl.28573$y...@nl=
pi068.nbdc.sbc.com:
>
> > We have a concrete pond with fish, and the concrete liner that is
> > exposed to the air has some black algae stains from when the water
> > level used to be higher. =EF=BF=BDThe new permanent water level is belo=
w the
> > stain. =EF=BF=BDWhat would be the easiest way to clean the dried black =
algae
> > without killing the fish? For example bleach would be great for
> > cleaning a white surface, except I think that would kill everything.
>
> Pressure washer.

pond stores sell algea killer stuff.

use with care.

On Tue, 5 May 2009 05:45:07 -0700 (PDT), bob haller <h...@aol.com>
wrote:

>On May 4, 9:25?pm, Red Green  wrote:
>> "scorpster"  wrote innews:ZRKLl.28573$y...@nlpi068.nbdc.sbc.com:
>>
>> > We have a concrete pond with fish, and the concrete liner that is
>> > exposed to the air has some black algae stains from when the water
>> > level used to be higher. ?The new permanent water level is below the
>> > stain. ?What would be the easiest way to clean the dried black algae
>> > without killing the fish? For example bleach would be great for
>> > cleaning a white surface, except I think that would kill everything.
>>
>> Pressure washer.
>
>pond stores sell algea killer stuff.
>
>use with care.

OP could consult an Ichthyologists, or just borrow a book from a
library on garden ponds and water gardens.

On May 5, 4:27=EF=BF=BDpm, Oren  wrote:
> On Tue, 5 May 2009 05:45:07 -0700 (PDT), bob haller 
> wrote:
>
> >On May 4, 9:25?pm, Red Green  wrote:
> >> "scorpster"  wrote innews:ZRKLl.28573$yr3.5461=
@nlpi068.nbdc.sbc.com:
>
> >> > We have a concrete pond with fish, and the concrete liner that is
> >> > exposed to the air has some black algae stains from when the water
> >> > level used to be higher. ?The new permanent water level is below the
> >> > stain. ?What would be the easiest way to clean the dried black algae
> >> > without killing the fish? For example bleach would be great for
> >> > cleaning a white surface, except I think that would kill everything.
>
> >> Pressure washer.
>
> >pond stores sell algea killer stuff.
>
> >use with care.
>
> OP could consult an Ichthyologists, or just borrow a book from a
> library on garden ponds and water gardens.

nature is sometimes best left natural:)

No work, no fuss, no hazard to fish...........

basic ignore algea.

>
> OP could consult an Ichthyologists, or just borrow a book from a
> library on garden ponds and water gardens.
>
Ichthyologists likely know nothing about live fish.  OP would be better off 
checking with a local aquarium or pond club or his neighborhood fish store.