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Water Changes

W

Worshiper

Member
Joined
16 Aug 2013
Messages
260
Hi guys,

I wanted to know if it is okay to perform a 30% water change about an hour after the lights go on(approx 2 hours after co2 goes on),😕

The reason I ask is I need to do some water changes, however, the lights timer goes on an hour before I get back from work. Do you reckon I change the timers for a couple of days?

Thanks guys!
 
I have changed 50% water in the evening before, when CO2 & lights have been on for hours and not suffered any issues. Just remember to turn CO2 off when filters are off if using inline diffuser, so as to not fill pipes with CO2 and much much more importantly ensure CO2 is back on when finished. 😳 (whoops forgot that once).
 
Thanks Ian. I had read somewhere that it affects photosynthesis.. and it also causes a change to the Co2 levels which aren't good for the plants.

ian_m said:
ensure CO2 is back on when finished. 😳 (whoops forgot that once).
Click to expand...

yeah 😉 i once forgot to switch the filter back on :banghead: .. for 8 hours! no adverse effects faced tho. 😀
 
Worshiper said:
I had read somewhere that it affects photosynthesis.. and it also causes a change to the Co2 levels which aren't good for the plants.
Click to expand...
It may do, but as only for hour or two makes no odds. Also generally fresh tap water, especially in hard water areas, may be already loaded with CO2 (and O2), which is why you can sometimes get monster plant pearling after water change.

Worshiper said:
yeah 😉 i once forgot to switch the filter back on :banghead: .. for 8 hours! no adverse effects faced tho. 😀
Click to expand...
I had no power for 3 days after house RCD tripped whilst away due to a supply neutral fault. Tank was less then 16C when I got back, just turned everything back on, tank & filter all fine. And yet you meet people who put their filter intake and outlet pipes into a bucket of water so they keep their filter running during tank maintenance so as to not make their filter anaerobic or starved or cold or some other reason....:facepalm:

My favourite is not turning back on, is the heater after water change...occasionally running for a week with no heater and tank running below 20C. Fish all appear fine but plants didn't grow the couple of cm I would normally expect.
 
ian_m said:
It may do, but as only for hour or two makes no odds. Also generally fresh tap water, especially in hard water areas, may be already loaded with CO2 (and O2), which is why you can sometimes get monster plant pearling after water change.
Click to expand...
That is very interesting. My MC pearls in my nano tank after a WC, otherwise it only has LC injected in and I wondered why there was O2 bubbles appearing each time!
 
ian_m said:
had no power for 3 days after house RCD tripped whilst away due to a supply neutral fault. Tank was less then 16C when I got back, just turned everything back on, tank & filter all fine.
Click to expand...
Whoa!

JamieB said:
That is very interesting. My MC pearls in my nano tank after a WC, otherwise it only has LC injected in and I wondered why there was O2 bubbles appearing each time!
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that's kool! I was always under the impression that LC doesnt cause the plants to pearl due there not being enough of gas saturation in the water so may be that explains why it pearls during a WC.
 
Worshiper said:
that's kool! I was always under the impression that LC doesnt cause the plants to pearl due there not being enough of gas saturation in the water so may be that explains why it pearls during a WC.
Click to expand...

I'm meaning that there must be CO2 in my tap water as they pearl after a WC 😀
 
JamieB said:
I'm meaning that there must be CO2 in my tap water as they pearl after a WC 😀
Click to expand...
Just goes to show the quality of water we get in the UK:lol:.. good for aquatic plants... bad for all other living organisms. :lol:
 
JamieB said:
I'm meaning that there must be CO2 in my tap water as they pearl after a WC 😀
Click to expand...
I think it's more to do with the water being closer to O2 saturation point after a water change. This is sometimes referred to as 'false pearling'


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Hi all,
Sk3lly said:
I think it's more to do with the water being closer to O2 saturation point after a water change
Click to expand...
I think it is a pressure and temperature effect. When the tap water is in the main it is cool and under pressure.

Gas solubility decreases as the temperature rises, and increases as the pressure rises.

When you add the water to the tank it isn't under pressure any longer and it warms, this leads to the dissolved gases coming out of solution. Because the atmosphere is 70% N2 and 20% O2, and <"neither gas is very soluble"> I would expect that the bubbles are mainly these gases.

You get the pressure effect when you open a bottle of carbonated drink, the CO2 is held in solution, but as soon as you unscrew the lid, and release the pressure, it out-gases as Co2 bubbles.

You can see the heat effect when you boil a kettle, as the water warms gas bubbles are evolved, until at boiling the water doesn't contain any dissolved gases at all.

cheers Darrel
 
Very interesting.. Well, shame it's not CO2 as that would be nice for the tank! Still, the more you know..
 
dw1305 said:
Hi all, I think it is a pressure and temperature effect. When the tap water is in the main it is cool and under pressure.

Gas solubility decreases as the temperature rises, and increases as the pressure rises.

When you add the water to the tank it isn't under pressure any longer and it warms, this leads to the dissolved gases coming out of solution. Because the atmosphere is 70% N2 and 20% O2, and <"neither gas is very soluble"> I would expect that the bubbles are mainly these gases.

You get the pressure effect when you open a bottle of carbonated drink, the CO2 is held in solution, but as soon as you unscrew the lid, and release the pressure, it out-gases as Co2 bubbles.

You can see the heat effect when you boil a kettle, as the water warms gas bubbles are evolved, until at boiling the water doesn't contain any dissolved gases at all.

cheers Darrel
Click to expand...
For my water changes i fill a container on a thursday, it sits there until sunday for my water change. The chlorine has 'gassed' or 'aired' off by this point (i do not know the technical term). I would assume all co2 and o2 would also reach an equilibrium with atmospheric conditions?? Am i correct in thinking this??

Now when i add this water to my tank, i get an increased amount of pearling for that first day. Now is it likely that this water is more rich in o2 than my tank water causing the pearling?? Or do you think as it splashes about during a water change its aerating it more thoroughly??

I will add i do get pearling throughout the week. Its just at an increased rate after a water change


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My tap and tank water have a difference of Ph of nearly 1 point, the tap being the lower. I pretty much think this is due to high CO2 levels. It outgasses very fast with the surface movement and/or airstone.
But one time I sent my fish to the surface. I did a large water change. I normally position the python so it splashes over the surface while it fills the tank but that time it had fallen in the water and I left it. All fish were gasping at the surface by the end of the water change. I dechlorinate with Prime and my tap water contains minor chlorine, no ammonia or nitrites at all. I've done water changes on one tank for weeks without any dechlorinator at all without absolutely no negative effect. So chlorine wasn't the problem. I put a large airstone and within 10 minutes it was back to normal.

Needless to say I now always make sure the incoming water splashes so the gasses come out quicker.
 
Hi all
Sk3lly said:
i fill a container on a thursday, it sits there until sunday for my water change. The chlorine has 'gassed' or 'aired' off by this point (i do not know the technical term). I would assume all co2 and o2 would also reach an equilibrium with atmospheric conditions?? Am i correct in thinking this??
Click to expand...
Yes.
Sk3lly said:
Now when i add this water to my tank, i get an increased amount of pearling for that first day. Now is it likely that this water is more rich in o2 than my tank water causing the pearling?? Or do you think as it splashes about during a water change its aerating it more thoroughly??
Click to expand...
Possibly, but probably not, either of these factors. It may be a temperature issue (if the water you've added is still cooler then the tank water?) or it maybe a nutrient effect if your water is rich in a limiting element (although presumably not if you use EI).

cheers Darrel
 
Hi all,
sciencefiction said:
My tap and tank water have a difference of Ph of nearly 1 point, the tap being the lower. I pretty much think this is due to high CO2 levels. It outgasses very fast with the surface movement and/or airstone.
But one time I sent my fish to the surface. I did a large water change. I normally position the python so it splashes over the surface while it fills the tank but that time it had fallen in the water and I left it. All fish were gasping at the surface by the end of the water change. I dechlorinate with Prime and my tap water contains minor chlorine, no ammonia or nitrites at all. I've done water changes on one tank for weeks without any dechlorinator at all without absolutely no negative effect. So chlorine wasn't the problem. I put a large airstone and within 10 minutes it was back to normal.
Click to expand...
Sounds like an oxygen or CO2 effect.

As well as CO2 (as H2CO3) being an acid, O2 is a base (so it is really O-H). If the water was either:
  • de-oxygenated
  • or high in CO2
  • or both high in CO2 and low in DO.
You would get the effects you describe on both pH and livestock with any of these scenarios.

cheers Darrel
 
Sk3lly said:
The chlorine has 'gassed' or 'aired' off by this point (i do not know the technical term).
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Very dangerous this, you must really always use a dechlorinator. The forums are full of people killing their fish, one guy lost about £600 of fish all in one go after a water change. This issue is chloramine.

Degassing water does not remove chloramine which may be in your water as standard or added to water by the water company in an emergency. I have certainly had chloramine added to my water for a couple of days after we had a water main burst. Water companies used to leaflet people when they did this, warning people not to use the water in their "aquariums & pond" but "but as everyone uses dechlorinator now", they no longer leaflet people.

As you will possibly not know when chloramine is added to your water, you must always add dechlorinator to your water before adding to the tank. If you really really really don't want to dechlorinate test the water with a chlorine test kit first.
 
ian_m said:
Very dangerous this, you must really always use a dechlorinator. The forums are full of people killing their fish, one guy lost about £600 of fish all in one go after a water change. This issue is chloramine.

Degassing water does not remove chloramine which may be in your water as standard or added to water by the water company in an emergency. I have certainly had chloramine added to my water for a couple of days after we had a water main burst. Water companies used to leaflet people when they did this, warning people not to use the water in their "aquariums & pond" but "but as everyone uses dechlorinator now", they no longer leaflet people.

As you will possibly not know when chloramine is added to your water, you must always add dechlorinator to your water before adding to the tank. If you really really really don't want to dechlorinate test the water with a chlorine test kit first.
Click to expand...
I am aware of the chloramine issue but thank you for the warning. I do run my water through a RO/DI unit. I cut my water with the waste that comes out of the unit. Should i still worry about chloramine or is there no need? I have a bottle if prime in my supplies anyhow


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Anyway apologies OP i have taken your thread in a different direction. Hopefully some of the info that has been shared has been useful to you.


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