Dr Mike Oxgreen
Member
When doing my 50% water change, I use 9 litres of rainwater from my water butt, mixed with 3 litres of unsoftened tap water. This gives me roughly the 3° KH and 6° GH that I'm after, and I can tweak the GH up a bit by adding MgSO₄ solution if necessary. I use Seachem Prime as my dechlorinator, and use a full-tank dose (only 0.5ml for my ~20 litre tank, so it would be impossible to measure any less). I boil a litre or so of the rainwater to bring the new water up to temperature.
I often notice that the gill rate of my Otocinclus has risen dramatically after a water change, and this seemed particularly bad yesterday. They were also very restless, and the chili rasboras were nervous as well - schooling very tightly and patrolling the tank rapidly. Most of the blue cherry shrimps seemed fine, but I did see one swimming very erratically and seeming to have difficulty staying upright. There also seemed to be a migration of snails heading up the glass towards the surface, within half an hour of the water change.
I decided that there might be a problem with lack of oxygen in the new water, although I must admit that none of the fish were gasping at the surface. To combat this, I added 15ml of 3% Hydrogen peroxide in the hope that it would provide some emergency oxygenation. (Actually it may have been after this that I saw the shrimp swimming erratically, not sure). After this, the chilies seemed to calm down slightly over the course of the next hour or so, and perhaps the Otos' gill rate slowed very slightly although still too fast.
So, does anyone know the typical oxygen content of rainwater that has been sitting in a water butt for a few weeks? I can't decide whether it's likely to be de-oxygenated or not. I am drawing water from the bottom of the butt.
Is there any point trying an oxygen test kit?
I can't think of any other contamination: the water butt is plastic, as is the house guttering. The roof tiles are old, so shouldn't be leaching anything into the water any more. The bucket and jug that I use are not used for anything else. That said, I don't know if it's my imagination but the tank didn't look quite as sparkly clear just after the water change - but that could be normal.
The tank looks okay this morning although I haven't yet done a head count.
Any thoughts? Would low O₂ level cause rapid gill movement in one species, but 'stressed' behaviour in another species, without any gasping at the surface?
I often notice that the gill rate of my Otocinclus has risen dramatically after a water change, and this seemed particularly bad yesterday. They were also very restless, and the chili rasboras were nervous as well - schooling very tightly and patrolling the tank rapidly. Most of the blue cherry shrimps seemed fine, but I did see one swimming very erratically and seeming to have difficulty staying upright. There also seemed to be a migration of snails heading up the glass towards the surface, within half an hour of the water change.
I decided that there might be a problem with lack of oxygen in the new water, although I must admit that none of the fish were gasping at the surface. To combat this, I added 15ml of 3% Hydrogen peroxide in the hope that it would provide some emergency oxygenation. (Actually it may have been after this that I saw the shrimp swimming erratically, not sure). After this, the chilies seemed to calm down slightly over the course of the next hour or so, and perhaps the Otos' gill rate slowed very slightly although still too fast.
So, does anyone know the typical oxygen content of rainwater that has been sitting in a water butt for a few weeks? I can't decide whether it's likely to be de-oxygenated or not. I am drawing water from the bottom of the butt.
Is there any point trying an oxygen test kit?
I can't think of any other contamination: the water butt is plastic, as is the house guttering. The roof tiles are old, so shouldn't be leaching anything into the water any more. The bucket and jug that I use are not used for anything else. That said, I don't know if it's my imagination but the tank didn't look quite as sparkly clear just after the water change - but that could be normal.
The tank looks okay this morning although I haven't yet done a head count.
Any thoughts? Would low O₂ level cause rapid gill movement in one species, but 'stressed' behaviour in another species, without any gasping at the surface?
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