excessive water changes?

deadlus3d

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Hello,

I was wondering if a weekly 50% water change is too much for my tank.
Could such a change alter the chemistry of the water too suddenly or is it advisable to change 50%?

Most info on the web is around the 10% 25% mark.

Regards,
 

sparkyweasel

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If you do the changes every week the water in your tank will not have changed very much so there won't be a big sudden change. If you have been doing smaller, and/or fewer water changes your tank water may be very different from your tap (or other source) water. So, if you're thinking of changing your wc routine it's a good idea to make the change gradually.
50%/week is normal for a hi-tech with EI dosing; in lo-tech you have a lot more leeway.
 

Tim Harrison

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I doubt it'll make much in the way of difference to water chemistry. But I'm sure your critters will appreciate the fresh water, and it'll help deter algae.
I often do a couple of 90-80% water changes a week.
 

Zeus.

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Depends on if your running a high tech or low tech tank.

Low tech you fine with 10-25%, my low tech I just top up with RO and WC few times a year - but low light

But high tech esp with high light and EI dosing 50% is strongly advised esp in mew setup, I sometimes do an 80-90% WC after a big trim in my 50l.

Also depends on biomass, higher the biomass the more Dissolved Organic Compounds (DOC) you will have so a larger amount of toxics in tank esp if high light.

Monitoring the TDS can be helpful as well and just keep an eye on it.
 

rebel

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50% FTW!

I do 60% because my pvc attachment is setup like that.

It is still not enough because in the wild, there is 100% water change per second not 50% per week.
 

dw1305

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Hi all,
If you do the changes every week the water in your tank will not have changed very much so there won't be a big sudden change.
I usually do small regular water changes, it suits me because it allows the rain-water to warm up over night before I use it in the morning. It also trickle feeds Daphnia etc. The water is often still appreciably cooler than the tank water, but some of the <"fish associate water entering the tank with food">.

If I've been away from the tanks I do a much bigger (or more frequent) water change(s) until I get back to somewhere <"near the conductivity datum level">.

I've never had any problem with this, but the rain-water won't be much different in chemistry from the tank water.

cheers Darrel
 

dw1305

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Hi all,
that is what fits in a 10l watering can!
I use re-cycled 3.4 litre (6 pint imperial) milk containers, it is quite interesting how long a "single use" plastic bottle can last before leaking.

We have been having milk delivered (in smaller bottles) since the end of March and I'm still using most of the milk cartons that pre-date this. A few I've has so long that they have grown a good crop of Acroloxus lacustris.

cheers Darrel
 

rebel

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it is quite interesting how long a "single use" plastic bottle can last before leaking.
And sobering. I feel guilty everytime I throw a milk container in the recycle which is every week or twice a week!
 

dw1305

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Hi all,
And sobering. I feel guilty everytime I throw a milk container in the recycle which is every week or twice a week!
My guess would be that if humans survive the next couple of centuries they are going to be fairly aghast at how profligate we've been with fossil fuels, water, soil etc.

cheers Darrel
 

Big G

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Hi all, My guess would be that if humans survive the next couple of centuries they are going to be fairly aghast at how profligate we've been with fossil fuels, water, soil etc.

cheers Darrel
Agree. I occasionally feel a bit guilty about all the water changing even though for me it’s no more than twenty five litres per week across two tanks plus evaporation top ups. Not so bad in summer as it goes on plants and grass in the garden. I probably perspire,respire and pass more than that much in a given week but well, you know.

There are a few huge heffalumps in the room when it comes to our custodial role of this planet.

I also share concerns with the OP (3d) but less on the chemistry because I think larger bodies of water must act as constant refreshment and exchange of chemicals unless its a stagnant lake (which a tank would be if we don’t do anything but top ups nor run some form of circulation I guess). It’s more about the fluctuating co2 which I have read in a few places MIGHT mitigate away from weekly large water changes in a low-tech/energy system as it could provoke algae.

However, just going on what I read as I have no skill, proof or learning to hand this on, providing there is sufficient movement at the tank surface, co2 is being exchanged all the time - inwards from air and outwards from plant photosynthesis then offgassing to produce an equilibrium of about 2-6ppm? Presumably the ’fresh’ stuff we put in is subject to these same laws so won’t cause too much of a shift, even temporarily, to the tank‘s residual co2 levels in the round?

Bg
 

dw1305

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Hi all,
It’s more about the fluctuating co2 which I have read in a few places MIGHT mitigate away from weekly large water changes in a low-tech/energy system as it could provoke algae....... providing there is sufficient movement at the tank surface, co2 is being exchanged all the time - inwards from air and outwards from plant photosynthesis then offgassing to produce an equilibrium of about 2-6ppm? Presumably the ’fresh’ stuff we put in is subject to these same laws so won’t cause too much of a shift, even temporarily, to the tank‘s residual co2 levels in the round?
We've had this discussion a <"few times on the forum">.

I think you are right and that is partially why I like a reasonable amount of water circulation, it means that levels of dissolved oxygen and CO2 follow atmospheric levels more closely, because you have a large gas exchange surface area for diffusion to occur from.

The equilibrium value (<"at 400 ppm CO2">) is only about 0.5 ppm CO2, but <"~3 ppm is usually given as the estimated value">.

cheers Darrel
 

Big G

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Thanks for the links Darrel. That Krib site is going to be worth some reading. A bit like some of the older threads on here. It’s good to see how things have changed in terms of thinking and also gear. Even the last three years seems to have shifted the overton window of what passes for aesthetics, equipment and practice. Back when I was a teen with my first tank the only really heavily planted tank I ever saw was at Tachbrook Tropicals in London, Victoria (sadly now closed).

One thing that never seems to change is algae problems :)

best wishes,

Bg
 

dw1305

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Hi all,
........I ever saw was at Tachbrook Tropicals in London, Victoria (sadly now closed).....
Unfortunately only one in an ever increasing <"horde of departed LFS">.
That Krib site is going to be worth some reading.
There is a lot of good stuff on there, but all now historical. Some of the posters are still active on <"Apistogramma forums"> and some formed <"AGA"> in the States.
A bit like some of the older threads on here
I'm biased but <"I dip in and out of UKAPS"> on <"other forums">.

I'm not personally aware of another resource with a similar quality archive, although I would guess there are German forums, that would be equally useful, if you can read German.
.......to have shifted the overton window......
I'm going to bet that no-one has ever referenced the "overton window" before on UKAPS.

cheers Darrel
 

Jerme

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One thing to remember with large water changes is that you use out the soil buffering capasity much faster. Because the soil also supports water purification and houses beneficial bacteria you loose these faster as well.
 

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