Re: [RML] Unhappy Xmas

Phil (peekay at
Tue, 19 Dec 2000 07:17:05 +1100

The smell you mention is suspicious. Perhaps there was some organic matter
left in your diatom filter from its last use, which rotted and went
anaerobic. When you returned it to the tank fish, dissolved gases such as
hydrogen sulphide and sulphur dioxide were released. These gases are very
toxic to fish, even in very low doses. In that situation, large fish would
die first. As gases are the culprit in this scenario, your
filtration/aeration act to vent the gases out of the water. Your air
curtain being off, obviously didn't help matters.

If this theory is correct, you should have found that any fish that were
going to die would have by the next day. By now the problem should have
cleared itself and treating would be pointless. Putting activated carbon in
the canister filters would have helped if done immediately.

Hope all is well now.


----- Original Message -----
From: "Ken Brook" <kbrook at>
To: <rainbowfish at>
Sent: Tuesday, December 19, 2000 12:23
Subject: [RML] Unhappy Xmas

> Dear ANGFA-ites,
> I need some help on a distressing mortality situation I encountered a
> few days ago. Location is Brisbane.
> Tank is 720 litres, Dupla CO2, quite a few plants, filtration by two
> 1800l/hr Otto canisters, extra surface agitation by Fluval 303 spray
> bar.
> CO2 gets atomised via a Rio 1700 powerhead and CO2 is on solenoid to pH
> meter. Air-curtain at rear of tank on all the time.
> No giggling now - this techno-jumble has been pretty stable for some
> time ....
> NH4 and NO2 are all zero. NO3 - 10-20 ppm pH 6.7-6.8 Temp currently 29C
> ~ 30C. Summer here.
> Water for changes is aged outside in a 200 litre container, dosed with
> Prime, agitated by small powerhead
> Was doing some maintenance before Xmas - well the 10 day cycle
> basically.
> (0) 8pm - tank looks good - all fish happily motoring about
> (1) Dropped out 200 l of water and replaced from water store at 9pm.
> Have done many times before. Fish all still seem happy enough.
> (2) Also decided to put Vortex XL diatom filter to shine the water up a
> bit for Xmas guests (not that it was that bad or anything - just to
> really get every fine particulate). Check everything and lights out.
> (3) Anyway next morning - total devastation - something has killed all
> my 5 Weipa Running Creek trifasciatas, 6 Bosemanni's,
> 3 Harvey Ck Blue Eyes, 3 Celebes, 5 Congo tetras, 1 Papuae, 1 large
> Bleeding Heart Tetra, 1 large cardinal - all quite large and about a
> year old.
> large Empire Gudgeon in trouble (and these things are built like little
> army-tanks). Dead bodies all over the tank.
> Affected fish classes near the surface. I have never seen such
> devastation before.
> Heartbroken. All these fish have been previously bullet-proof -
> surviving all minor diseases that have popped up from time to time
> in other fish. All big 3-4 inch fish too. Dead fish have no obvious
> marks or symptoms.
> (4) But the possible culprit - bloody Precision 9500 airpump failed
> during the night - with 2 new rubbers (10 days old) rupturing - cripes
> !!
> But one Running Ck, one huge Papuae, 2 incisus, a Parkinsonii,
> Inornatas, Mucullochi seem OK
> Most tetras, Corys, platies, and gouramis are OK and swimming about
> normally. Many of the large fish though are dead.
> Theories:
> Chemical contamination - hard to see how or what ?
> Room had a slight stale /rank odour at midnight but I couldn't find a
> source (like the tank itself) - thought maybe smell from some water on
> the carpet or old socks :-)
> or something. But room smells fine again today.
> One shop owner said Brisbane chlorine levels are very high at the moment
> but I reckon I double dose anyway with Prime so should be OK. Anyway
> water aged for 3-4 days normally.
> Diatom filter hoses had a slight odour about them (stale old water
> internally) - but were well flushed before use. And no diatom powder
> didn't cloud the aqaurium - primed in small container.
> Pseudomonas or Aeromonas outbreak triggered by water change suggested by
> one LFS owner ? Dunno - water looks pretty good today... clear, smells
> OK. But anyway maybe an hypothesis worth a thought. Would Octozin treat
> this sort of problem - LFS's suggestion ?
> Or simply lack of oxygen caused by ruptured air pump and adding 200 l of
> water from a relatively sealed drum? (theory maybe low O2 in drum
> water). But LFS folks reckon plenty of filtration with other systems as
> a counter. Drum has been used a number of times before with no problems
> including discus tanks.
> CO2 acidosis - well cylinder hasn't dumped - and bubble rate is OK.
> Looks same as always. pH/kH/CO2 numbers seem OK to me. I've set pH
> controller at 6.9.
> So any theories as to how such a prang would have occurred would be
> welcome. I'm currently wearing a black-arm band.
> Regards & Xmas greetings to all.
> Ken