HELP! pond repaired, fish dying

[Meyer Jordan]

Nitrate does not accumulate in a pond at the same rate as in an aquarium. It is highly unusual to find Nitrate levels in a pond greater than 30 - 40 ppm. Aquaria are quite often much higher than this. Thus, a reduction of 30+ ppm is not going to cause a problem. I seriously doubt that the difference is more than 20 ppm, if that.
Incidentally, if you look around the web you will find scant evidence supporting the belief in Nitrate Shock.

 

[Weirdness555]

I'm not sure, our tap water is at 30ppm nitrate, and the fish have been in a very small patio pond for a long time with limited water changes. Not that I don't believe you, I'm just worried as I don't want any more fish to die, it's really upsetting for all of us, especially my mum.

 

[Meyer Jordan]

30 ppm Nitrate level in your tap water. I thought the UK had tighter restrictions on the quality of drinking water. You will not find levels that high in the U.S. The maximum permissive level here is 10 ppm.

 

[Weirdness555]

This is from when I had my aquarium, it never dipped below 30ppm according to my test kits. I might be mis-remembering, but I couldn't get my tank below that no matter how many water changes I did.

 

[Weirdness555]

Apparently the maximum level recommended by WHO is 50ppm (50mg/l)

 

[Meyer Jordan]

Apparently the maximum level recommended by WHO is 50ppm (50mg/l)

Pond owners outside of the U.S. must fight algae problems most of the time. As if there were not enough other things to manage in a pond.
Anyway, the argument against Nitrate Shock still applies, now the baseline is higher.

 

[Faebinder]

It's not the nitrates and if the ph is that high then its definitely not the nitrates cause they lower the ph.
I don't know why you have high ph in both ponds but 8-9 ph is not good for the goldfish and will lead to a shock IMO.

You'll need water changes regardless.

 

[Meyer Jordan]

It's not the nitrates and if the ph is that high then its definitely not the nitrates cause they lower the ph.
I don't know why you have high ph in both ponds but 8-9 ph is not good for the goldfish and will lead to a shock IMO.

You'll need water changes regardless.

Although the established pH range for drinking water in the USA is 6.5 - 8.5. In the United Kingdom where the OP resides the established range is 6.5 - 9.5. It is very likely that 9.0 is the pH of the source water. Koi (and Goldfish) can adapt to these high pH levels. This only increases the importance of maintaining a high Alkalinity.
Our neighbors across the big pond have to deal with a different set of base parameters than us Yanks do.

 

[barryian]

Results for patio pond: Ammonia 1-2, pH 9, others 0, nitrate unknown. This is since moving the filter media over. I'm really worried about what will happen with ammonia if they stay in the patio pond much longer. Is there anything that could be killing them other than parameter shock? If I can convince my mum they won't all die from some hidden poison she might be able to move them tomorrow morning

The patio pond ammonia at 1-2ppm becomes extremely toxic at a high pH, especially 9.0 ... That right there is enough to cause damage.

 

[Weirdness555]

I've told my mum to keep adding water then to put them in this afternoon

 

[Weirdness555]

And we had a massive blanket weed problem when we first set the pond up, but we dealt with it by covering the pond surface with water lilies and floating plants like water lettuce. I expect the same thing will happen this summer, since the plants all got disturbed. I'll send my parents out for more water lettuce when this is sorted out. - with regards to the high nitrates

 

[Meyer Jordan]

With your source water boasting a 30 mg/L Nitrate level, dealing with elevated Nitrate is going to be a on-going battle.

 

[Faebinder]

With your source water boasting a 30 mg/L Nitrate level, dealing with elevated Nitrate is going to be a on-going battle.

He's gonna need lotsa plants.

I would look into trying to refill some of the pond with rain water if you can collect it safely.

 

[Weirdness555]

My mum won't put the fish back she is convinced that the cement is killing them, she says there's white dust on some of the rocks. Is that possible?

 

[Meyer Jordan]

Is any of the cement repair work submerged?