Can you have too soft water?

I recently did a water change in a tank, where I changed about 1/3 of
the water with laboratory grade RO/DI water.
We're talking water with a conductivity of less than 1 µS/cm, perhaps
1/20th of the conductivity of a hobbyist grade RO/DI unit. Basically
distilled water.

Soon after, I noticed that the sailfin tetras in the aquarium showed
signs of nerve damage - they twitched and convulsed when they tried to
swim. They also stopped eating, and stayed hid for two weeks.

All the while I was going "What the... ?" and trying to figure out
what disease or poison might have struck. Finally, I decided to follow
the old adage "when in trouble or in doubt, do large water changes".

The day after, the sailfins were out moving again, although even
today, two weeks on, they're not fully recovered (perhaps they never
will).

So - what are the symptoms of osmotic stress in fish? Is it possible
that the water simply got too pure, that there was too little
electrolytes in the water for the tetras? Was I supposed to mix some
table salt in the RO/DI water before use?

Yes even fish that like soft water need some minerals in the water. I have
found many times when I used to keep SA cichlids that if the water was too
soft they would start to scratch themselves on the rocks until I added some
salt & hard water.

--
Craig Williams
_________________________________

www.Canadiancray.tk
"Mean_Chlorine" wrote in message
om...
I recently did a water change in a tank, where I changed about 1/3 of
the water with laboratory grade RO/DI water.
We're talking water with a conductivity of less than 1 µS/cm, perhaps
1/20th of the conductivity of a hobbyist grade RO/DI unit. Basically
distilled water.

Soon after, I noticed that the sailfin tetras in the aquarium showed
signs of nerve damage - they twitched and convulsed when they tried to
swim. They also stopped eating, and stayed hid for two weeks.

All the while I was going "What the... ?" and trying to figure out
what disease or poison might have struck. Finally, I decided to follow
the old adage "when in trouble or in doubt, do large water changes".

The day after, the sailfins were out moving again, although even
today, two weeks on, they're not fully recovered (perhaps they never
will).

So - what are the symptoms of osmotic stress in fish? Is it possible
that the water simply got too pure, that there was too little
electrolytes in the water for the tetras? Was I supposed to mix some
table salt in the RO/DI water before use?

Mean_Chlorine wrote:
We're talking water with a conductivity of less than 1 µS/cm, perhaps
1/20th of the conductivity of a hobbyist grade RO/DI unit. Basically
distilled water.

Which means it's unsuitable to support life in any form.

--
Victor Martinez
Owned and operated by the Fantastic Seven (TM)
Send your spam he
Email me he

Victor Martinez wrote in message ...

We're talking water with a conductivity of less than 1 µS/cm, perhaps
1/20th of the conductivity of a hobbyist grade RO/DI unit. Basically
distilled water.

Which means it's unsuitable to support life in any form.

Yes, but 2/3's of the water in the tank was still aged, if fairly
soft, tapwater, and sailfin tetras are extreme blackwater fish... I
thought there'd be enough electrolytes in there for them. Guess not.

(Mean_Chlorine) wrote in
om:

So - what are the symptoms of osmotic stress in fish? Is it possible
that the water simply got too pure, that there was too little
electrolytes in the water for the tetras? Was I supposed to mix some
table salt in the RO/DI water before use?

If you add salt, don't add table salt. Table salt has extra additives in
it that are not good for your fish. Get aquarium salt. Or, you can also
use kosher or rock salt, but I've found aquarium salt at the local PetSmart
to not be very expensive; so, i use that. You probably don't need nearly
the amount directed for general use as a "tonic."

(Mean_Chlorine) wrote:
I recently did a water change in a tank, where I changed about 1/3 of
the water with laboratory grade RO/DI water.
We're talking water with a conductivity of less than 1 µS/cm, perhaps
1/20th of the conductivity of a hobbyist grade RO/DI unit. Basically
distilled water.

Soon after, I noticed that the sailfin tetras in the aquarium showed
signs of nerve damage - they twitched and convulsed when they tried to
swim. They also stopped eating, and stayed hid for two weeks.

All the while I was going "What the... ?" and trying to figure out
what disease or poison might have struck. Finally, I decided to follow
the old adage "when in trouble or in doubt, do large water changes".

The day after, the sailfins were out moving again, although even
today, two weeks on, they're not fully recovered (perhaps they never
will).

So - what are the symptoms of osmotic stress in fish? Is it possible
that the water simply got too pure, that there was too little
electrolytes in the water for the tetras? Was I supposed to mix some
table salt in the RO/DI water before use?

Any idea what your KH was? It's remotely possible that the RO water diluted an
already-marginal amount of buffering capacity to the point of causing a pH
crash.

Andy Hill wrote in message . ..

Any idea what your KH was? It's remotely possible that the RO water diluted an
already-marginal amount of buffering capacity to the point of causing a pH
crash.

Yes, I considered that. The KH was about 3, but that was some time
ago. Anyway, I dissolved two heaping tablespoons (this is a 90 liter
tank) of bicarbonate in water and poured it in, but it's made no
visible difference.

The crenuchus now eat, but still 'twitch' now and then. Despite
repeated water changes and the bicarb, something is still not right,
but I'll be darned if I know what it might be.

I'm stumped.

I've pretty much decided to tear the tank down and set it up afresh,
with all new rocks, driftwood & sand.

All the inverts in there - tons of shrimp, snails, copepods, little
worms etc - look as happy as ever, otherwise I'd have suspected heavy
metal poisoning.

Before you give up, check with the Greater Seattle Aquarium Society,
web site www.gsas.org.

Seattle has water that is naturally incredibly soft. The water
districts have to harden it to keep it from eroding copper pipes in
the system. The perm hardness test out to 0 or 1 (GH 3 or 4, kH 3)
before adjusting, every time. Before I knew what the problem was I
lost snails - they were fine until their shells decalcified, developed
holes, then just flat dissolved. Every fishkeeper in the area has had
to deal with this (whether we knew it or not!).

GSAS has folks who can tell you exactly how to handle soft water and
how it will affect various fish. Seattle also has a school of
fisheries at the university, and some of the faculty are GSAS members.
We also have a big NOAA presence in town (the fed fish, ocean, etc.
research people). So, GSAS has members with some amazing backgrounds
in fishkeeping and water chemistry.

Good luck! Celest

"Mean_Chlorine" wrote in message
om...
Andy Hill wrote in message
. ..

Any idea what your KH was? It's remotely possible that the RO water
diluted an
already-marginal amount of buffering capacity to the point of causing
a pH
crash.

Yes, I considered that. The KH was about 3, but that was some time
ago. Anyway, I dissolved two heaping tablespoons (this is a 90 liter
tank) of bicarbonate in water and poured it in, but it's made no
visible difference.

The crenuchus now eat, but still 'twitch' now and then. Despite
repeated water changes and the bicarb, something is still not right,
but I'll be darned if I know what it might be.

I'm stumped.

I've pretty much decided to tear the tank down and set it up afresh,
with all new rocks, driftwood & sand.

All the inverts in there - tons of shrimp, snails, copepods, little
worms etc - look as happy as ever, otherwise I'd have suspected heavy
metal poisoning.

The missing number (or maybe I just missed it) is the gH. I've been
keeping pieces or coral (about the size of my finger) in many tanks
lately (even soft water fish). My kH and gH is about 2-3dH. I've been
doing this to increase the buffer, but after reading, now I'm starting to
worry about the gH. I occasionally hear about someone keeping fish in RO
water, but I don't know how they do it. Maybe their substrate or
rockwork is leeching.

Metal poisoning is a strong possibility, as is a heavy dosage of chlorine
or chloramines (during pipe maintenance). I'd be tempted to check with
your municipality and your local aquarium society.

NetMax