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Most efficient water change method for large tank

idris

Member
Joined
3 Jan 2011
Messages
816
Location
Herts
My tank is 250L and 2ft deep.
For water changes it's always been "easiest" to ...
  1. pump water from the tank into a 25L canister (I have a small external pump for this)
  2. drag the canister outside and empty it
  3. fill the canister with tap water
  4. add dechlorinator etc,
  5. heat the canister to match the tank.
  6. pump water from the caister back into the tank.
Even doing a 10% water change takes best part of an hour and has always been a bit of a PITA. If I want to do 20%, even more so. Consequently I procrastinate and don't do it as regularly as I should ... with obvious consequences.
Finding a more efficient way to do water changes will hopefully help me be a more diligent aquarist and having a healthier aquarium.

I've looked at Pythons (branded and DIY) but I'm wary of them for two main reasons:
  1. You have to add chlorinated water directly to the tank.
  2. It's harder to ensure you get the tap water at the right temperature,
As I've had a couple of occasions where I've wiped out all the fish in the tank when doing a water change without ever been able to say for certain why, I'm reluctant to run tap water straight into the tank.

Any suggestions on a more efficient way to do water changes?
 
Do you mean a system that is filled constantly, but very slowly, from the mains water, and then overflows into a drain?
If so, nice idea, but there's no easy way to route mains water to the tank on a permanent basis.
 
Hi, I have a large water butt which I fill 24 hrs before a change, it holds around 200 litres and my house tank is 350 so enough for a 50% change. It's in my fish shed which is insulated and kept at 20C so gets to near enough tank temperature. I don't add any dechlorinator.
I use 1" hose with a foam prefilter to syphon to the drain, this takes 15 mins max for 150+ litres. While this is draining I clean the prefilter on my filter and circulation pump. I then connect the pipe to a pump in the water butt and fill the tank, another 15 mins.
If I don't do any other trimming the total time including clearing up is 40minutes. Needs a good size pond pump.
If you have somewhere to keep the butt and hose you can pre-fill with hot/cold water and add dechlorinator then pump.
Cheers
John
 
Do you mean a system that is filled constantly, but very slowly, from the mains water, and then overflows into a drain?
If so, nice idea, but there's no easy way to route mains water to the tank on a permanent basis.
Obviously I don't know the lay out of your house but, I have my tanks plumed into the mains water supply via 6mm RO tube.
The white 6mm pipe is quite easy to hide, in fact mine goes up from the kitchen sink (very easy DIY fittings available) into the loft and back down into my lounge tank. This involved two 6mm holes in the ceiling but honestly it would only take a dab of filler to hide them if we ever sold the house.
In my case I have a mini RO ball valve attached to the rim of the tank so all I have do to perform a water change is run some 6mm air line & start a syphon into the sink & let it auto top up the tank.
 
Sadly adding a mains feed would involve either lifting most of the kitchen floor, taking down the ceiling or going through an external wall twice.
And a water butt would put give me a similar situation to which I already have, as I have indoor space and would still have to decant it and heat it.
 
I'm working on a DIY water change system at the moment as like you with 6 tanks smallest 200lt water changes take forever.
I will post a video when I'm happy with it.
I have now all the materials & so far cost about £20 for all 5 separate tanks & no tank drilling required, there are a lot more to syphons than just suck & let it flow!
 
At the moment I drain my tank direct out the window that is 2ft from the aquarium. Then I run the hose on low and refill from there as I have no fish. The only difference I will have once I get fish is that I will be adding some Prime to the tank as it is filling during water changes. I would really like to go external from outside tap to run into a water butt and feed from that but the effort to do so at this time I don't think I will be.
 
Finding a more efficient way to do water changes will hopefully help me be a more diligent aquarist and having a healthier aquarium.

The most efficient way is always the easiest way for the same reasons you stated....otherwise one starts dreading it.

....I know you mentioned you wiped your tanks twice by doing a water change..which must have been a horrific experience....but.If you hadn't changed much water very often in the first place, your tank and tap water in time would get million years apart...Doing the odd larger water change can shock the fish in this case ..or your water company had the odd large dump of chlorine/chloramines and your dechlorinator wasn't up to it. I've used a python for years, the day after I upgraded to larger tanks after it took me half the day to fill one tank up with buckets :) I have never had a problem doing large water changes straight from the tap. They fish are active and happy even while I do a water change. Varying the temperature up to 2-3 degrees is also just fine. I use my hand to roughly make sure its not too cold or too warm. Use quality dechlorinator like Prime. You can buy it cheaply online and it is very concentrated....lasts a long time. I normally put 1.5-2 times the recommended dose(for the tank size) just before I start filling...

If you think of it, putting dechlor in a bucket and then pouring the water is just one extra step. Pouring the full dose of dechlor for the tank directly in the tank is the same thing. Prime is active for 24-48hrs...It will be effective the moment you start pouring tap water for longer than it takes to fill the tank...unless it takes you two days :)
 
Ok. +1 for pythons.
Though I'd disagree about adding decjlorinator to a bucket - considering I leave that to warm up with a spare aquarium heater, I've been working on the theory that that has a good chance to work before it's added to the tank.
 
Entirely possible. I don't know.But in a 250L tank there is the possibility that the distribution of chlorine etc and dechlorinator don't match.
A couple of times I've had a lot of dust algae to scrape off the glass. Once this is in the water it can take 10-15min to get filtered out of the water, and it isn't distributed around the tank evenly. So if dechlorinator and untreated water are getting mixed in the tank, there's a significant chance fish can be "chlorinated" for more time than I'm comfortable with. I mix them in a smaller canister, especially if I put the dechlorinator in first, the mix will be much quicker and the fish won't be effected.
 
I feel the OP. I've got a 800L tank and water changes are a b*tch. I should ideally be preparing the water in a large plastic tank, but this isn't possible for that kind of volume. So what I do at the moment is that I do small water changes (like 25% weekly or every 10 days) directly from the tap and add dechlorinator in small doses as the water goes into the tank, taking advantage of the flow that the water coming in creates, and I am guessing that this flow distributes the dechlorinator evenly.

The dechlorinator is one thing though, my main concern is the temperature; the new water is usually >5'C lower than the tank water (in the winter it's more like 15'C lower, maybe more). The only solution to this that I came up with is the very slow introduction of the new water, it takes me about 3 hours to do the water change.

Any ideas very welcome. Looking forward to KipperSarnie's video.

Edit:

When using water directly from the tap, I believe that the key is in the frequency of the changes. If I would be changing the water every two or three months, a 50% water change using tap water would be guaranteed to wipe the entire tank.
 
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If you hadn't changed much water very often in the first place, your tank and tap water in time would get million years apart...Doing the odd larger water change can shock the fish in this case ..or your water company had the odd large dump of chlorine/chloramines and your dechlorinator wasn't up to it. I've used a python for years, the day after I upgraded to larger tanks after it took me half the day to fill one tank up with buckets :) I have never had a problem doing large water changes straight from the tap. They fish are active and happy even while I do a water change. Varying the temperature up to 2-3 degrees is also just fine. I use my hand to roughly make sure its not too cold or too warm. Use quality dechlorinator like Prime. You can buy it cheaply online and it is very concentrated....lasts a long time. I normally put 1.5-2 times the recommended dose(for the tank size) just before I start filling...

If you think of it, putting dechlor in a bucket and then pouring the water is just one extra step. Pouring the full dose of dechlor for the tank directly in the tank is the same thing. Prime is active for 24-48hrs...It will be effective the moment you start pouring tap water for longer than it takes to fill the tank...unless it takes you two days :)

That. I'm with you 100%.
 
A couple of times I've had a lot of dust algae to scrape off the glass. Once this is in the water it can take 10-15min to get filtered out of the water, and it isn't distributed around the tank evenly.

Dechlorinator acts by chemical reactions...not by flow and distribution. The effect is immediate...What you are afraid of is fear itself. All I would be worried about is putting enough dechlorinator to neutralize the amount of chlorine your water company adds normally. That's why I do a double dose just in case they've dumped more than usual..However, if that's the case...mixing in a bucket can't save you either...
If you age your water, it may help some more against a higher dump by the water company(unless they dose chloramines which needs dechlorinator) but the containers where water is aged will start going through nitrification in a matter of days too(2-3 days max), and there's a chance you add water with ammonia and/or nitrite in your tank...if you age the water for too long....a week could be too long.
 
This is what I use, to change 100l odd of water. Means quick tank vacuum, quick trim and refill all done in under an hour.
https://www.ukaps.org/forum/threads/water-change-heater-project.25877/

I used the above and not heating the water as some people "state the fact" that I will kill all my fish. I can report tank water dropped to 18'C, fish not bothered in fact seemed to like swimming in and out of the incoming water flow !!!.

You really must use dechlorinator to remove chlorine and chloramine from the tap water. Some dechlorinators will remove heavy metals, but in UK heavy metals are in such low levels not a problem for fish.

The chlorine/chloramine has two issues once in the tank, it will irritate fishes gills and will kill bacteria. Generally this will not kill fish as chlorine/chloramine will react with organics in the tank and not be round long enough to be fatal to fish. This is why some people get away water changing with tap water only, that is until the much stronger chloramine is added to the water and they kill their tank !!!

However chlorine/chloramine it will kill bacteria in your filter pretty effectively, so if you dose the tank with dechlorinator and then add tap water, make sure your filter is off. If you kill your filter bacteria with tap water it will start rotting and a day or two after adding tap water will leech lethal levels of ammonia into your water, promptly killing your fish. This is why people get their fish deaths a day or two after doing the undechlorinated water change.

I did have some links where someone lost £650 of fish (in many tanks) shortly after water changes as he thought bubbling air though a storage tank of water would dechlorinate it effectively. Unfortunately the water company started dosing chloramine after a burst water main and possible water contamination. Again a few pence of dechlorinator would have saved the fish (and filtration). Testing the water after the event revealed ammonia levels off the scale (5ppm) from both rotting filters and chloramine breakdown products.
 
Ian_m...you're are talking of a scenario where one does not add dechlorinator in the water...I agree, you must use a dechlorinator and it must be at a dose enough to counteract whatever the water company doses. I do have my filters off during a water change but in my small tanks the purpose of that is defeated because I've got internal filters mostly...not an issue either pouring tap water directly and dosing the tank with dechlor directly..
 
The reason i was asking is because i add the declorinater directly to the tank. I have been down the route of using brewing buckets to airate and heat the watet and as the OP says it is a pain and makes you dread water change days to be honest.
Now i just syphon the water fron the tank. Add declorinater direct to the tank and fill with the hose. Alot easier.
Sure i do get a slight temp drop of 2 to 3 deg but have seen no problems with this. Temp is the main reason i do two 25% water changes a week instead of one large 50%.
 
Water changes are preferable to be on the larger side at once to actually have an effect because concentrations of harmful substances rise all the time...But lets be unreasonabe and assume that the new water is pure and the concentration of whatever you're trying to remove from the tank never goes up...

Then for example, if you want to bring 40 ppm nitrates to a 5 ppm level

Daily water change @

70% - takes 2 water changes
50% - takes 3 water changes
40% - takes 4 water changes
25% - takes 7 water changes
20% - takes 9 water changes
10% - takes 19 water changes

To reduce 1ppm ammonia to 0.0X ppm where X is a value below 5 ( the lower you want to bring more toxic substances down, the more water changes it takes)

Daily water change @

70% - takes 3 water changes
50% - takes 4 water changes
40% - takes 6 water changes
25% - takes 14 water changes
20% - takes 9 water changes
10% - takes 29 water changes

People tend to do one weekly water change....So if you are a low volume water changer...e.g. 10-20% weeky, it will take you a quarter to half a year to remove 1ppm ammonia from your system....You might as well not do water changes... The best thing is to adopt a method where large volumes of water changes are done at once....If you have a python, you just sit and watch with a cup of coffee....maybe taking videos...I actually put a bit of food at the same time and watch the fuss...Fish forget someone is fiddling with the tank...
 
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