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Water changes, top-ups and dechlorinator

Jaap

Jaap

Member
Joined
30 Sep 2011
Messages
1,068
Location
Nicosia
Hi

many of you use dechlorinator when doing a water change and I have started using it myself since my tank is suffering from Diatoms all year long and its possible due to this. However, when I add water to top-up the evaporation, I don't use dechlorinator. I am adding 1L in the morning, 1L midday and 1L in the evening in a 40L tank. Could that have a negative effect?

Thanks
 
Hey, I think it will depend if your water has any sort of significant amount of ammonia or chlorine and the likes that may affect the nitrification balance, which leads to diatoms. If not, then it's hardly an issue.
I tried myself testing the suitability of my water doing 50% water changes several weeks in a row without adding dechlorinator because my water is sort of lacking much of anything harmful. The fish were perfectly fine and unaffected and as a matter of fact I didn't cause any diatoms at all or any algae. I started using the dechlor back in case there are heavy metals that may affect the fish long term.

But overfeeding one of my tanks for a period of time while raising fry led to a massive diatoms outbreak(yet again). It was growing up until a few days ago actually.
My fry went to different tanks then I cleaned up the tank completely from the algae, cut out affected plants, etc, cleaned the substrate, filters, everything... Did a couple of 90% water changes in a row and I am immediately back to no algae growing. I put fish back in the tank but they are adults so I no longer overfeed.
So find the source of your organics. Diatoms are due to raised ammonia levels here and there for one or another reason. If your tank can't deal with them with the provided plants and filters, then add more/fast growing plants and/or add another filter. Or check your oxygen levels in case they are the limiting factor for nitrification.
 
When I top up, I put new water direct into the tank and put enough dechlorinator for the entire amount of water IN the tank not just added. (in my case 1.25ml). Read somewhere on here it was best to dose the entire water when topping directly into the tank.

Also of note is evaporation concentrates bacteria in the tank as only water will evaporate, the rest stays behind so always stick to your weekly changes.
 
Jaap said:
However, when I add water to top-up the evaporation, I don't use dechlorinator. I am adding 1L in the morning, 1L midday and 1L in the evening in a 40L tank. Could that have a negative effect?
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Yes, the chlorine and/or chloramine in your water will kill the bacteria in your filter or at least stop them establishing in sufficient numbers to keep water clean. May or may not have any effect on fish.

I don't know why people don't use dechlorinator it doesn't cost much (Prime is 3.6pence for your whole tank :banghead:), and as you have found saving a few pennies not using it causes all sorts of issues.

See here for costing and sodium thiosulphate which is even cheaper than Prime.
http://www.ukaps.org/forum/threads/water-changes.37407/page-2#post-404058
 
ian_m said:
I don't know why people don't use dechlorinator it doesn't cost much (Prime is 3.6pence for your whole tank :banghead:), and as you have found saving a few pennies not using it causes all sorts of issues.
Click to expand...

It costs me enough with several tanks water changes largely and regularly, two of the tanks are large enough. I bought two 500ml bottles only a few months back, cost me 50-60 bucks and I am running out already. On top of buying fancy food and electricity bills, replacing heaters, failed lights, etc... everything adds up. And I don't even need it as my water is pretty clean from harmful stuff but just in case...and Prime is still my cheapest option.

For a solo 40l tank I agree it's very inexpensive though.
 
sciencefiction said:
And I don't even need it as my water is pretty clean from harmful stuff but just in case...and Prime is still my cheapest option.
Click to expand...
Sodium thiosulphate is even cheaper, but if your have chloramine in your water (common in US) you need to double the dose. Just premix with RO/distilled/boiled water in a squirty bottle and squirt into your water. Done...cheaply.
 
Nope, I am in Ireland. They don't use chloramines here to treat the water. There's barely chlorine in the water, no ammonia, no nitrites and miniscule nitrates. But I can't say about heavy metals or the odd chloramine treatment if they do it. There've been issues around with heavy metals in drinking water in some rural areas around, hence I use the dechlorinator because it apparently took them a couple of years to announce it/admit it to the public. Prime is handy because it works out cheaper for me, but not cheap enough.
 
If Jaap has been doing full water changes with straight tap without any consequences to fish(premature death, regularly sick from the stress of it, etc...) possibly his water is generally fine too and not loaded with disinfectants. It will affect the fish too if one is killing a bit of nitrifying bacteria daily or suffocating the fish with chlorine. I mean if 1l at any one time of non dechlorinated water causes enough shock to the filter bacteria, then his water must have quite the amount of something harmful.
 
sciencefiction said:
I mean if 1l at any one time of non dechlorinated water causes enough shock to the filter bacteria, then his water must have quite the amount of something harmful.
Click to expand...
Any level of chlorine will be toxic to bacteria, after all it is put in the water as a disinfectant. Even small amounts (0.01ppm) will kill bacteria in a day or two.

Generally incoming water will have at max 1ppm chlorine (usually less), my Southern water is 0.5ppm.

Digging around I see

0.01ppm is maximum fish will tolerate.
0.37ppm will kill all fish.

Figures from
http://pondplace.com/dangersofchlorine.aspx

Seen similar figures for tropical fish, actually even worse as chlorine toxicity increases with temperature, seen 0.001ppm being quoted.

Adding dechlorinator will reduce this to 0ppm in a couple of minutes.
 
The thing with chlorine is that it dissipates once in a tank because of the surface movement or maybe something else, chemical reactions of sorts. It doesn't last in there. My tap either doesn't have chlorine/is lower than the levels you quoted above or else.... because I've done 50% water changes in a row for several weeks without any negative effects to plants/algae, bacteria/filters or fish.
Plus I wash my sponges under the tap too during maintenance although I don't wash all filters at once.

Edit: I forgot to mention the tank had shrimp in it too and they too weren't bothered. So I don't know why it doesn't affect the tank. It says our water is treated with chlorine only but still there is chlorine in it to some extent. I forgot how much.

I think Darrel had somewhere an explanation why chlorine is not a big issue in certain amounts.
 
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As Jaap is using dechlorinator for his water changes I'd just suggest fitting a lid to stop the epic evaporation.

3l a day from a tank holding probably 35-37l is around 8% of volume :eek:
 
James O said:
As Jaap is using dechlorinator for his water changes I'd just suggest fitting a lid to stop the epic evaporation.

3l a day from a tank holding probably 35-37l is around 8% of volume :eek:
Click to expand...

Well my friend :) Its either 3L of evaporation due to the fan on the tank or 32 degrees Celsius of tank water :) I think I made the right choice here unless I get a chiller...
 
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