Soft water = fish death in large tank?

[Phantom]

Hi,

I've had a run of deaths in a 350L tank of mine over the past 2 months. I've just tested water hardness and noticed that the tap water is much softer than it used to be. My test kit goes to a result colour on the first drop, so it's very low. My tank is now sitting at 1-2 GH / KH rather than the 3-5 I saw when I last tested it around July. pH seems to be stable though given the volume.

It's mostly been guppies and killies. I don't mind the guppies as they'll just breed rapidly but the death of a few killies is tough. I've also lost a few fish in some other tanks, however, they could be from old age.

Question is, can soft water cause fish to die? Also, could the council have done something with our Chch water post earthquake to soften it / do I need to treat my water before putting it in the tank? I called the council and they said it's safe for people but wouldn't give me an answer on what was in it or if they've changed anything since the earthquake.

Also, if pH is stable given the volume of water etc, do I need to raise the hardness? I'm not really a fan of adding stuff to tanks, I prefer to let them find their own equilibrium etc but help it along with things like driftwood and plants. If I need to raise it, is there a good way to do it naturally? I'm guessing I'd need to add shells etc, but I don't want to raise the pH if I can help it.

[Ira]

Question is, can soft water cause fish to die?

No. Shock from changing from hard to soft can.

Also, could the council have done something with our Chch water post earthquake to soften it

Very unlikely. There no real cost effective way of softening water on that large of a scale especially given that it's totally unnecessary.

Also, if pH is stable given the volume of water etc, do I need to raise the hardness?

No.

[henward]

any form of shock will killf ish

water params a major one.

imagine your fish is living int his water for ages and if it suddenly changes, it will cull the weaker less adaptible ones.

same as humans

if you get someone from the deserts of africa wearing a loin cloth.

and throw them into a siberian mountain unconditioned and unprepared, they will die.

[David R]

Lack of TDS/trace elements in very pure water like RO or rain water could lead to long-term problems with some fish, would seem unlikely with tap water though.

[Phantom]

Cheers.

I'm really just trying to figure out what could be causing it.

I don't shock them, when I do water changes, it's only about 10 - 20% and I trickle feed the water in over an hour or so. Nitrates and phosphates tend to stay pretty low due to plant growth.

I will try treating the water with dechlorination products on the next change in case they've put more in the water. Can't taste it though.

[Rabbit]

What was the Kh? as your Gh will have very little effect on the fish, live bearers (guppy's included) prefer higher ph with the buffering of kh obviously.

[Phantom]

Both GH and KH were around 1-2 degrees. I've seen reports online saying they like it a bit harder, however, they've been in similar water conditions for well over a year.

[suphew]

Have you tested your pH at different times of the day, eg morning then evening, if not it might be appearing to be stable but actually swinging during the day

[suphew]

Also, could the council have done something with our Chch water post earthquake

It's more likely they have stopped doing something they used to do, councils adjust water to keep it neutral cause it saves other problems. I'd think this would be well down in the priority list at the moment

[Phantom]

Have you tested your pH at different times of the day, eg morning then evening, if not it might be appearing to be stable but actually swinging during the day

I've tested it 4 times since yesterday morning just for my own sanity. Same result every time. The tank isn't over stocked and 350L is a lot of water to swing the pH in.

I think tonight I'll just do a large water change but run it all through a filter I have, add some ager / dechlorination product and through a UV filter just to be extra safe.

[fishplants]

Hi Phantom,

sorry to hear about yor fish deaths. With regards to your tapwater hardness, I believe the hardness level you are seeing is fairly typical for central Canterbury, where tapwater is untreated artesian supply. I live in Rolleston and my hardness levels are identical to yours. When I lived in Linwood they were also the same. My TDS in Rolleston is in the low 70's ppm.

The only thing I can suggest is to ring the council and ask them if they have changed bores/done any renovations or modifications to pipework or storage tanks/started treating the water with chlorine etc.

I think there was another thread recently where someone was asking about the ChCh water supply and it's quality post-earthquake.

cheers

[alanmin4304]

The hardness of Christchurch water supply is generally aroung 45ppm expressed as calcium carbonate. If you ring the Council and ask them about gh & kh they will not have a clue what you are talking about. This is soft by international standards but has been about that figure for many years. The nitrate levels will increase as you move from the Wiaimakariri towards lake ellesmere. All live bearers do better with a little salt and hardness added to the water.