# Water change practice



## sisko (2 Aug 2008)

Hi,

The subject tells everything. I'm just curious who does it how!   
Do you guys age your water? If yes for how long? I age 40 litres for a few days in a big plastic bin. When I fill it up(usually on friday afternoons) I add some Tetra Aquasafe and keep it circulating until sunday. When the day comes I add the TPN+ to it and just pump the water into my Rio 180. So far this is the best I could work out. I find the bucket system too messy and wet!   
So who does it how?


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## TDI-line (2 Aug 2008)

I roughly drain out about 2-300 litres (out of 720), then stick the garden hose in, fill to the top, and add ferts and chemicals.


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## aaronnorth (2 Aug 2008)

On my big tank - 180l - i fill it up with a hose pipe which is fitted to a tap connector and it goes on the kitchen tap. dechlor added while filling.

My smaller 60l, it is just as quick to get a washing up bowl and fill it that way, dechlor added in bucket, then TPN+ after evrything is running again.

both  50%


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## spaldingaquatics (2 Aug 2008)

I feel left out here.....

I change 25% of my 230l once a week

I remove the 25% with a jug, replace with buckets that have each been dosed with a dechlor solution and topped off with boiling water from the kettle to take off the 'chill' of tap water.

I have a 40l and 20l that I change about 50% each week and replace with dechlor water from a bucket. Got to be careful with refills because the substrate is sand.


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## sisko (2 Aug 2008)

spaldingaquatics said:
			
		

> I remove the 25% with a jug, replace with buckets that have each been dosed with a dechlor solution and topped off with boiling water from the kettle to take off the 'chill' of tap water.
> 
> OMG! How long does it take??  :?:


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## JamesM (2 Aug 2008)

No water changes in my 45 gal. 

I change 50-60% in my 20 gal each week via a jug and bucket. Refill is the same. Takes about 5 minutes.

Happy days, as Dan would say


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## spaldingaquatics (2 Aug 2008)

sisko said:
			
		

> spaldingaquatics said:
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About half an hour to 45 mintues, I use the w/c time to inspect the tank, sort out problems, replant uprooted plants, syphon gravel ect, so I don't mind that it takes so long because I get to make sure the tank is in perfect order and, well...hey, it's fun!  

The wifes kettle gets a hammering though


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## PM (2 Aug 2008)

I change 50% one or twice a week of my 54L ATM.

Takes 15 mins


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## JazzyJeff (2 Aug 2008)

I empty 200 litres from my 500litre tank in my lounge, out my patio door and water my garden with it, syphon off any debris and then pump 200 litres back in from my storage barrelin my fishhouse(shed) in the garden, while I sit and watch it fill up with a cold beer !!!!!!!!! Ahhhhhhhh


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## a1Matt (2 Aug 2008)

JazzyJeff said:
			
		

> while I sit and watch it fill up with a cold beer !!!!!!!!! Ahhhhhhhh


I like Jeff's technique best so far!

I do a 50%ish WC weekly on my 160litre tank with hoses connected to the bathroom taps via a showerhead adaptor.

Takes about 20min to empty into the bath (via gravity, over a 10m hose run), during which time I do any tank maintenance.   Takes between 3-10min to fill up depending on how much I open up the bathroom taps.  Dechlor added straight into the tank while filling up.

Being a bit of a daydreamer, sometimes I forget I am emptying the tank and drain up to 90% of the water by mistake!  The fish do not get stressed with large WC's or with the dechlor added straight in the tank.

They do get stressed if I make quick movements and do really quick water changes.  For that reason I do a slow gravity fed emptying of the tank, and only have the taps open slightly for a slow refill.  I turn the canister filter output down to really low throughout as well. 

I also keep the plug in the bath when emptying so that I can see the clarity of the water coming out.  That along with the flow rate from the filter helps me determine when to give the filter a clean.  I also use that water for cleaning out the tanks cover glass, or the filter.

Easey peasey!  Gone are the days of buckets and sucking on siphon tubing for me!


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## Egmel (4 Aug 2008)

a1Matt said:
			
		

> Easey peasey!  Gone are the days of buckets and sucking on siphon tubing for me!


I'm a bucket girl still... but it only being a 70l it's probably easiest!

I don't suck on the siphon but instead use the dunk it principle to get the siphon started.  

I start with a snail cull and any pruning required.

I siphon the debris out along with the water and use this to water my ornamental plants (I still don't feel entirely safe putting it on my veg... even though I know I don't add any nasties to it).  I usually do about 3 x 12 litre buckets (so ~50%), if I'm cleaning the filter then I turn it off and rinse each bit in reverse order (so cleanest bit first) and I do this in each bucket so everything gets cleaner on each iteration.  If I'm not cleaning the filter then it is just left running throughout.  I almost always do the water change after lights out so I'm not worried about CO2 loss.

Filling up is also done with buckets, I'm a heathen and use the mixer tap to take the edge off the cold water during winter but in this weather I just add cold.  Again with a sand substrate you have to be careful how fast you tip the water but I use my fingers to dissipate the flow so it's usually ok.  I add the dechlor to the buckets as I'm filling them and the fets once I've filled the tank.

Last off I double check for any snails I can get and that all the plants are how I want them.

I've thought about having a python-esque system but I've decided to wait until I've got a bigger tank... which in turn means waiting until I'm not a student and not trying to fit my life into a single room


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## Themuleous (5 Aug 2008)

I'm a bucket and mouth full of water person.  But will be using a powerhead and pipe to empty and fill the new 4ft tank.  I'll being using part rainwater so i can move away from RO as the waste water kills me every time I watch it run onto the grass.  I have also invested in a giant pond carbon prefilter http://www.koi-fish.co.uk/acatalog/Detox_Pond_Dechlorinators.html
to run the rain water through before it goes in the tank just in case there are any nasty things in there and will run the tap water through it as well to remove the chlorine and heavy metals which should mean I dont have to use any chemicals at all to treat the water!

Not sure what I'm going to do about heating it though.

Sam


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## Tom (5 Aug 2008)

I syphon 50% (15l !!!) into a bucket, throw it down the toilet (bucket not included  ), fill it up with cold tap/rainwater, and a tiny bit of hot tap (same source as cold water, just hot  ), dechlorinate, fertilise and fill. 5 minutes. I don't heat the tank at all, so I don't really need to use much hot water, just enough to take the edge off. Tank runs at 22-23 degC. 

Tom


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## planter (5 Aug 2008)

I use alot of RO water, have done from the start. I live in a hard water area and find the Ro reduces the KH If I dont reduce KH I have to use Co2 at a silly rate to get drop checkers into the green. 

Syphon off 50% into bucket/container and water conatiner plants in garden!

I fill 25 litre drums 75% RO 25% tap (to add back some minerals) set the barrel up on a set of steps beside the tank and syphon from barrel to tank. 

50 % water change every week (often a day or 2 late) and dose with TPN+


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## mick b (5 Aug 2008)

10% by volume (30 galls) per night.
RO & HMA filtered tap, blended direct into tank at 5 galls/hour.
(Low tarrif electric heats etc).

Water is piped direct to tank, from a mini-water treatment system in the 'car-port', then up the drain-pipe, via the attic to the tank. Over-flow is directed to flower beds in the front garden (under-floor drain system).
(Waste water from the RO goes to my Garden Pond)

I go to bed, wake up, get a coffee, 
Dose EI feed the fish and munch a bagel while watching the fish have brekky!

Cheers,  Mick B
(PS, Discus like lots of water changes  )


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## Themuleous (5 Aug 2008)

planter said:
			
		

> I use alot of RO water, have done from the start. I live in a hard water area and find the Ro reduces the KH If I dont reduce KH I have to use Co2 at a silly rate to get drop checkers into the green.



Planter, you're doing something wrong if thats the case, the hardness of the tank water doesn't change how much co2 you have to pump into it, as its a fixed relationship between KH/CO2/pH.  What water are you using in the drop checker?

Sam


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## LondonDragon (5 Aug 2008)

I just use my DIY water changer, 50% out and then 50% back in, and thats all done and dusted in about 15 minutes! both tanks (125l & 60l) take me around 30 minutes to do, and its just sitting there watching it empty and fill again!


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## planter (5 Aug 2008)

Themuleous said:
			
		

> planter said:
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Am i Missing something? 
Im not trying to adjust KH with Co2

The KH is the buffer capacity of the water right?
The waters ability to hold or stabilse Ph right?
Therefore A high Kh = a high buffer capacity that will require increased amounts of Co2 required to lower PH right?

At low KH levels PH is more unstable right? therefore more easily adjusted? Im just reducing the amount of Gas I need to use to drive the ph down to the required level.

I use 4dkh in the drop checker when I can be bothered to use one.


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## ceg4048 (5 Aug 2008)

planter said:
			
		

> Themuleous said:
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Hi Chris,
           We were trying to hash this out before, and it's worth revisiting. Sam is correct in that the ph/KH/CO2 relationship is fixed. At high KH values a small drop in PH equals a high concentration of CO2. The buffering ability of the high KH prevents the ph from dropping but it doesn't prevent the CO2 from dissolving in the water. At low KH values, since there is less buffering capacity, the pH falls very easily. So, in low KH water the same CO2 concentration (as described for the high KH water) causes a large drop in pH.

This can easily be seen in the CO2 tables http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Look down at the bottom of the table where it shows that in distilled water adjusted to a KH of 15 the pH will drop to 7.2 when the CO2 concentration level is 28 ppm.

Compare this to the top of the chart which shows water adjusted to a KH of 1.5. You can see that the same 28 ppm CO2 concentration drives the pH down to 6.2 which is 10X the acidity at which the 15 KH water is driven to, yet the CO2 concentration is identical. Now, if I wanted to drive the pH of the 15 KH water to a pH of 6.2 using CO2 it would require a CO2 concentration of 284 ppm CO2.

Neither stability of pH, nor KH can affect the ability of the water to dissolve CO2. Therefore, you should not have to change the injection rate of the CO2 just because you have a higher KH. This is fundamental so there is some other phenomenon occurring in your tank if the dropchecker behavior is not consistent when using tap water versus RO water.

Cheers,


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## aaronnorth (5 Aug 2008)

thats cleared a lot of things up for me too Clive, thanks for that.


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## planter (5 Aug 2008)

Thanks for your explanation Clive

I must be the only thicko on the forum who has had this much trouble getting his head round this   
You will forgive me but I never did do chemistry.

You mean to tell me that ive been lugging around bloody great barrels of RO water for nothing?? lol
I tell you what im going to do - next tank (coming soon) im gonna fill it with tap water! and use it as a learning exercise.

Perhaps I should re install my drop checkers and stop guessing?
Ill stick to the aquascaping while you guys keep me up to speed on the chemistry. 

And thanks Sam you may have just saved me a fortune with the chiropracter   .


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## Themuleous (5 Aug 2008)

Sorry to have started something!  My intention wasn't to point out a fault Planter  just that if you are using RO purely to reduce the amount of CO2 you are adding then you're making work for yourself 

It is bloomin' confusing I must admit but I think this is what is most important 



> Neither stability of pH, nor KH can affect the ability of the water to dissolve CO2. Therefore, you should not have to change the injection rate of the CO2 just because you have a higher KH.



I guess the other thing to remember is that the pH scale is logarithmic i.e. pH 6 is 10x more acidic than pH 7 and similarly, pH 5 is 100x more acidic than pH 7.  Im no chemist but its probably this fact that accounts for the apparent 'fixed' relationship between CO2, pH and KH. (But I could be wrong :LOL

Sam

EDIT - alls well that ends well


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## planter (5 Aug 2008)

Themuleous said:
			
		

> Sorry to have started something!  My intention wasn't to point out a fault Planter  just that if you are using RO purely to reduce the amount of CO2 you are adding then you're making work for yourself
> 
> It is bloomin' confusing I must admit but I think this is what is most important
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Im glad you did start something Sam, No pont using a forum that doesnt help!


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## Themuleous (5 Aug 2008)

Haha  guess not!!

Sam


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## mick b (5 Aug 2008)

Excellent explanation, thanks.

Coming from the Discus side of things, CO2 tends to be considered as a Ph reducing tool as it promotes the take-up of KH, thus reducing Ph, hence the parallel with using RO to reduce TDS (including kH) again to drop Ph

I learned someting today,  Cheers,  Mick B


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## Ed Seeley (5 Aug 2008)

I'll wade in here as I use RO too.  I use it as I keep soft water fish and find I get better results with plants and fish using it.  I don't waste any water as the 'waste' feed goes straight into my koi pond!

One thing koi keepers have found is that koi grow much faster in softer water than harder and also changes the way their colours develop so there may be more to using soft water for naturally soft water fish like koi than simply survivability and breeding.


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## ulster exile (6 Aug 2008)

For those people who use a pump or other semi-automated system, what do you do about cleaning the substrate?  I tend to leave it alone, as most of the tank's substrate is covered and I presume that the build up of mulm will help the plants but having religiously gravel vac'd for about 2 years, leaving the substrate just feels 'wrong' :?


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## JamesC (6 Aug 2008)

Planter was correct all along regarding disolving CO2 in water with varying KH's. The higher the water's KH the more difficult it becomes to dissolve CO2 in the water and hence the more CO2 is needed to be injected to compensate for greater CO2 loss. It's not a great difference but it is detectable. 

James


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## plantbrain (6 Aug 2008)

However, whether the CO2 gas is dissolved or not may not matter at all, all that matters is that enough CO2 gets to the plants.

If you add say 3 bubbles per second in a a tank with a KH of 10 and another with a KH 1, you still add exactly the same amounts of CO2 gas, pH is not even considered here, go directly to CO2.

A ph/Kh combo of 6.0 and 1 = 30ppm
A pH/KH combo 7.0 and 10 = 30ppm

It takes the same amount of CO2 gas to get 30ppm from ambient conditions, yes, the CO2 can have differing solubility at different KH's, however, this is not going to make any real practical differences to plants or the CO2 system.

It does make some differences in natural systems where CO2 is not enriched like we do it often in CO2 planted tanks, subtle changes can make differences there, but not in our aquariums.

This is where practical applied knowledge and consideration comes into play versus trying to compare things to natural systems and relationships. While true is some regard, it has virtually no effect near as I can tell using a a wide range of KH's and CO2 meters over the years. I've had less than 1 Kh to upwards of 12 degrees for several years at a time, a few plants are weak at higher KH's, but it had nothing to do with CO2.

Temperature decrease also increases the ability for water to hold more dissolved gas(all, not just CO2) as well.
Higher you go, the more steam and boiling water vapor you get.

I think this is a big issue for folks that tend to use RO water/and keep Discus, they tend to use higher temps, then have large fish, all issues when it comes not only to CO2, but O2 as well.

To increase O2, often they increase the wet/dry filters, add more surface turn over, but this has nothing to do with KH does it?

Nope, not one bit.

I know much more about saltwater systems and CO2 unfortunately, but the balance of these carbonate species (which ultimately affects the solubility of carbon dioxide), is dependent on factors such as pH. In seawater this is regulated by the charge balance of a number of positive (e.g. Na+, K+, Mg2+, Ca2+) and negative (e.g. CO32- itself, Cl-, SO42-, Br-) ions. Normally, the balance of these species leaves a net positive charge. With respect to the carbonate system, this excess positive charge shifts the balance of carbonate species towards negative ions to compensate. The result of which is a reduced concentration of the free carbon dioxide and carbonic acid species, which in turn leads to an oceanic uptake of carbon dioxide from the atmosphere to restore balance. Thus, the greater the positive charge imbalance, the greater the solubility of carbon dioxide. In carbonate chemistry terms, this imbalance is referred to as alkalinity.
So harder water will have higher solubility of CO2.
CO2 dissolved in the ocean immediately reacts with water to form carbonic acid. Most of the carbonic acid gives up a 
proton (H+)â€¦dissociatesâ€¦to form bicarbonate. Some of the bicarbonate dissociates to form carbonate. Thus harder water holds more or put another way, CO2 is more soluble in harder water.

As far as use of CO2 required for a tank, this is *another area*.
Refer to Fick's 1st law of diffusion.

This is really the biggest issue for us, not so much the KH, that's more for certain species of plants and fish.
Diffusion is the biggest issue and the ability for the CO2 to get to the plants is the primary driver here.

More current = more off gassing, however it also means less boundary layers and better CO2 delivery/mixing and harder for many species fo algae to attach, less detritus on leaves providing fuel for algae and other periphyton growth.
More current also means more stable O2 levels and often higher levels.

So this is a trade off, one long ignored and neglected at the expense of the fish and plants.
We can add a tad more CO2 and get the benefits of more stable O2, better CO2 delivery, better mixing and less algae/dirt in our tanks.

This seems to be a good trade off to me.
If you can, a lower KH is nicer for more plant species, most every hard water plant can do very well in soft CO2 enriched aquariums(I've not found one to date that cannot do well). But low KH is not going to save folks from algae or CO2 woes.

Just keep that in mind there.

CO2 and alkalinity are the two least understood topics in this hobby.

Even back in the mid 1990's folks where telling others to watch how they measure CO2 and the KH issues:
http://www.thekrib.com/Plants/CO2/hardn ... frank.html

Read bottom of the page. I had pretty high PO4's in my tap back then and ignored the pH/KH and went with fish and plant responses for 30ppm(later determined using RO reconstituted).

Hope this helps, likely confuses, but the bottom line is worry more about the Fick's 1st law than solubility.
As far as fish and perhaps a few plant species, focus on lower KH's 3-5 seem okay for most so called low KH plants.

Folks that claim super low pHs and low KH's in the 5.5-6.0 ranges or KH's at 1 or so are required for any plant full of beans. Look for advice elsewhere.

Regards, 
Tom Barr


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## JamesC (6 Aug 2008)

All very interesting but it doesn't get away from the fact that in an open system it requires more injected CO2 to hold a constant CO2 concentration in a high KH water than in a low KH water.

Does it really matter that much? No, not really. Just increase bubble rate a bit.

James


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## aaronnorth (7 Aug 2008)

> If you add say 3 bubbles per second in a a tank with a KH of 10 and another with a KH 1, you still add exactly the same amounts of CO2 gas, pH is not even considered here, go directly to CO2.



yes you add the same amounts of CO2 gas, but less of it will dissolve in the tank with a KH of 10 so more will need to be injected to reach 30ppm wont it?

thanks, aaron

(its probobaly just me getting confused again   )


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## ceg4048 (7 Aug 2008)

What Tom is saying is that even at very high KH the solubility of CO2 is still very high. You won't see much of a difference in the injection rates and it most certainly doesn't warrant bucketloads of RO water, that's for sure. 

The common misconception is that the tank water should be driven to the same pH regardless of it's KH. This is not true as I tried to illustrate with Chucks table. For all intents and purposes you should consider the solubility the same. As James points out, you may need a minor adjustment to bubble rate but the difference will not be significant.

CO2 in the tank water comes out of solution into the air bubble in the dropchecker, then diffuses into the dropcheckers sample water. The change in pH of this dropchecker water is different than that of the tank because it is has a KH of 4. When the dropchecker turns green (pH 6.6) this tells you that the concentration in the dropcheker's water is 30 ppm. This also implies that the tank water has 30 ppm although the tank water's pH can be totally different based on it's KH and it's acid content.

Another thing to remember is that only a tiny fraction of the CO2 that is injected in the water actually reacts to form carbonic acid. We see this reflected as a pH drop but the vast majority of the gas stays as CO2.

Cheers,


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## aaronnorth (7 Aug 2008)

so you are saying unless you have an extremely high kh of lets say 20, then nobody needs to worry about the confusion of needing to inject a lot more CO2?


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## ceg4048 (7 Aug 2008)

Yeah, that's the bottom line. There are folks out there with KH even above 18 and they don't report any difficulty injecting CO2. There are a lot more things that affect CO2 uptake to the plants than high KH, such as poor flow or inefficient delivery methods, or even insufficient injection rates.

Now, as Tom indicated, there are plants that don't like high KH, but these are only a handful. So if the plant doesn't grow well in high KH water it's not because CO2 doesn't dissolve well, it's because that plant doesn't like high KH.

Cheers,


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## aaronnorth (8 Aug 2008)

thats sorted all my confusion out   quite simple really!


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## Egmel (8 Aug 2008)

ceg4048 said:
			
		

> Yeah, that's the bottom line. There are folks out there with KH even above 18 and they don't report any difficulty injecting CO2.


Will second this, I have a KH of 15-17 and on my 70l I can get ~30ppm with DIY! (when it's not leaking  )


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