# Treatment of top up water?



## Tim Lee (15 May 2022)

I was wondering if anyone can advise what they use to treat the water they use for their pond top up?
I have a carbon canister filter used in line on garden hose but not sue of its efficacy and if there are issues re. The chemical  difference of tap water and the pond water?
Any advice would be much appreciated.


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## not called Bob (16 May 2022)

personally I use sodium thiosulfate


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## Paul Willi (16 May 2022)

i dont treat my tap water when topping up my pond and never had any issues
cheers


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## martin-green (16 May 2022)

I would say it doesn't really matter what you use when topping up a pond, since unlike a fishtank a pond is outside and as soon as it rains the water chemistry changes. Some say you should use a dechlorinator, but unless you know how much water you are adding to your pond how much dechlorinator do you use? 

Koi pond owners will use umpteen in line filters and all sorts, but for your average garden pond, I really would not worry.


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## Tim Lee (16 May 2022)

Thanks guys, it is a planted pond but does have some koi and orfe so was just playing cautious.


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