Item For Discussion - How Do You Refill The Tank After A Water Change?

Most of us use one of two methods when doing a water change. We either empty the tank into a bucket with a siphon tube then refill with a bucket, adding dechlorinator to each bucketful of new water. Or we empty water out using a hosepipe, add dechlorinator to the tank then refill through the hosepipe.

There is a school of thought that both of these are not as safe as we might think. There is a suggestion that while dechlorinators react with chlorine instantly it takes time for every single chlorine molecule to meet a dechlorinator molecule. In other words, when refilling with a hose there is chlorine in the tank for several minutes before it is all removed and during this time it can affect both fish and bacteria. Even using a bucket is not safe as it takes time for every single chlorine to be removed.

It has been suggested that we should let each bucket of water stand for 30 minutes before pouring it into the tank. Or leave an airstone running in the bucket for 5 minutes. This allows time for every chlorine to meet a dechlorinator. For those with large tanks, the suggestion is to run the new water into a very large container (or several small ones), add dechlorinator, wait half an hour then use some sort of pump to refill the tank from the container.


If we could be certain that our water company uses chlorine, then leaving the new water to sit overnight would allow chlorine to gas off. But some water companies use chloramine which doesn't gas off. And virtually all dechlorinators also contain something to detoxify metals, important for tanks that have invertebrates such as shrimps and snails. Most of us will always use dechlorinators for one or both of those reasons.



Discuss........

I fill my buckets in the evening, running the water through a nitrate reducing filter (the water in my area has very high nitrates), leave them overnight with a heater so they can reach a similar temperature to the tank water.

I then add dechlorinator and aquarium vitamins to the buckets in the morning about 15-20 minutes before I do the water change.

I have 2 tanks, when I do a water change I use a bucket (2 bucket fulls). I turn off the filters and heaters. However I don't use any dechlorinator and I have never had any problem with my fish afterwards. I live in a hard water area. Am I just lucky?

Hi Folks,

Interesting discussion. It's so long since I used tap water for my tanks that I have forgotten how I used to do water changes at that time. So many factors to consider. Also, when dechlorinators go to work on chloramine, they break it down into chlorine and ammonia. So, dechlorinators not only have to deal with chlorine and chloramine, they then have to remove the ammonia. And the heavy metals. Such products should really be known as tap water conditioners, not simply 'dechlorinators'. I note that King British De-Chlorinator states:

"King British De-Chlorinator makes tap water safe for fish by instantly removing contaminants from the water that cause skin and gill membrane irritation, including chlorine, chloramines, heavy metals and excess ammonia".

The above product contains sodium thiosulphate, EDTA, sodium sulphite and Aloe vera.

I'll stick with remineralized RO water.

JPC

So, dechlorinators not only have to deal with chlorine and chloramine, they then have to remove the ammonia.

Just a thought - would there be any benefit in measuring chlorine and ammonia before, during and immediately after a water change? If that's too much, what about before and after? We'll leave the heavy metals for the moment!

JPC

Why are the dechlorinators which contain aloe vera bad for fish? I have always used Stress Coat.

Why are the dechlorinators which contain aloe vera bad for fish? I have always used Stress Coat.

As said already, it coats the fishes’ gills, although it doesn’t seem to have an adverse effect in small doses. I use Haloex which contains aloe vera, but at a small proportion of 1ml per 20 litres I’m not too worried. The main reason I’ve never used anything else with it in is... why on earth would I? For one thing, Aloe vera is a plant that grows in semi-deserts. Why would I add it’s juice to my fish? Another thing is, why would I want to aid my fishes’ mucus production? They already have enough.

The whole Aloe vera thing with regard to fish was just a huge gimmick. AV became the latest health craze. It was good for just about everything, so obviously it was also going to sell if they say it’s good for fish. And everyone fell for it. Nobody asked “why would my fish need help with mucus production when they’re producing enough already?”
The whole gimmick played on the myth that a water change is a risk to fish health, and the fish need protecting from the new water, whereas the reality is that only a bad water change, with ‘bad’ water (chlorine, temperature, different hardness and pH etc) is a bad thing. A water change with good, appropriate water is always a good thing and fish need no protection at all from it. They just need the chlorine/chloramine/ammonia gone and the metals neutralised. Good water is much better for them than Aloe vera.



I use a water butt for water changes. It holds 50 gallons and does a 45% on my 6x2x2. It has 5 old kernackered heaters in it that don’t turn off anymore. Before I use it I plug em in. Takes a few hours to get up to temperature. When it’s ready I syphon half the tank into an outside drain, then put the drain end of the pipe onto the pond pump that’s in the water butt. That pumps the water butt into the tank. Then I refill the butt from the tap, add haloex, and leave it for a week with a little internal filter full of PolyFilter to (almost) purify it.

I don’t need the haloex if there’s just chlorine in it, but at certain peak times my water board will use chloramine instead. From what they told me, most if not all UK water authorities use chloramine at least occasionally, as and when required.

Seachem won't say what's in Prime. But the fact that they claim so many things for it means it's a cocktail of chemicals which personally I wouldn't allow anywhere near my tanks!

Does anyone know how much ammonia is left from chloramine? Enough to harm the fish? Enough to actually show up in our tests? Occasionally I have tested a bucket of new water after adding dechlorinator and had no trace of ammonia.

Or make pH the next topic?

During today's water changes, I tested the dechlorinated water in the bucket for ammonia. Zero. Either my water company doesn't use chloramine (or at least, not today) or they do but the amount of ammonia is so small it can't be measured.