Percentage Of Water Change On Larger Tanks

Hi all

I have a 100L tank and am considering at some time in the future upgrading to something about double the size. However, the only thing putting me off is the water change.

Currently I change two large bucket fulls a week, which is about 25L or 25% of my water volume. Whilst this isn't a massive chore, it does take a good half hour, boiling kettles, syphoning and slowly puring back in. I'm not sure whether I am changing too much. However, at this rate I'd be having to make up four large buckets a week with a larger tank.

Can anyone reliably advise whether larger tanks need less volume/less frequent water changes or not. Or indeed whether say 10-15% a week would be sufficient on a 200L tank?

Tank size is really pretty irrelevant to the size of water changes, once the filter is cycled: it's all about stocking and bioloads.

If you have a lot of fish, or large messy ones, you'll need to a larger % in water changes weekly.

I know what you mean about the hassle of doing changes, but it is necessary for the good health of your fish. Perhaps you could look at making the changes easier on yourself? Do you need to use the kettle for heating the water for example; unless your house is ancient and poorly maintained, it's usually fine to use water from the hot tap.

You can also use a hose to empty and refill the tank; lots of us with large or multiple tanks do it that way. You just have to remember to dose enough dechlor for the whole tank, rather than what you've removed (as some of gets bound up by organic compounds present in the tank) before you start refilling.

A mixer tap helps, so you can temperature match, but I don't have one; I use straight cold water, but trickle the new water in very slowly so I don't shock the fish. Just for instance, I did a 75-80% change on my 240l bedroom tank a couple of days ago (it wasn't meant to be that big, I stopped watching 'cos I was on WoW ) and I took two or three hours refilling. I don't find that a hassle, as long as I'm not having to lug buckets around I don't mind the extra time it takes.

On any size tank, the percentage water change largely depends upon the stocking, in order to remove the nitrate (presuming you are not getting an ammonia or nitrite spike).

Over the course of the last few three days, I've done at least a 75% water change (by syphon and two buckets totalling 25l) on my 566l; 240l; 140l; simply because I was around and not having to fit in work shifts. Ordinarily, my tanks get 50% weekly changes, with the exception of my heavily stocked Rio240 (48 Lionhead Cichlid teenagers and their mum plus 8 Ilyodon xantusi young adults) and my Ilydon fry tanks which get two changes a week.

You could try a hose straight from the tap to fill back up, aslong as you you keep it at a slow flow rate, the temperature difference wont be too sharp.

There is a thread in the DIY section on how to build a 'python' to save you having to use buckets at all:

http/www.fishforums.net/index.php?/topic/388430-tutorial-diy-python-system/page__hl__python

So you can add water straight from the tap into the tank and then add the dechlorinator to the tank ? I've been adding it to the new water before I put the water in the tank. I was worried that I'd kill the bacteria if I put tap water straight in

dazbud said:

So you can add water straight from the tap into the tank and then add the dechlorinator to the tank ? I've been adding it to the new water before I put the water in the tank. I was worried that I'd kill the bacteria if I put tap water straight in

Click to expand...

Not if your filter is turned off.




Tom

I have a 250L tank in my living room and to make my life easier I bought a long length of tube off of ebay and took the short tube off of my gravel vac and attatched it to that. Now while im doing my gravel vac it runs straight off down the downstairs loo (you could use the kitchen sink).

Also no need to boil kettles if you use a good quality decholorinator it deals with any metals that may be in the water. I change 25% one week and 50% the next but thats just my preference.

i changed 75% and 50% on my 5ft tanks today and it took 30-40 minutes for both. i use a length of pond filter hose as a syphon to get the water out, straight out the front door on 1 tank and straight into the garden from the 2nd tank. when refilling i use a hose on a mixer tap in the kitchen, get it to the right temp then fill the tanks.

i add enough dechlor to treat the whole tank which isnt much when using prime anyway and add it before i refill. give it 5 mins to get spread throughout the tank then add the water.

just sit back and have a cuppa while it basically does it itself

water changes are a ease for me i have a 8 tanks n a 30 per cent water change is done in jus over 20mins i have a modified hose pipe with a siphon on the end then the other end is the tap easy!!! i siphon then attach it to the tap job done,,, i jus turn off my filter and add seachem prime and the new water straight from the tap

Surely filling your tank with 50 % of cold water straight from the tap can't be good for the fish. I always used to mix buckets of hot/cold to bring the temp up to a reasonable level but using buckets is a pain. I had intended using a hose this time around but the tap water is ice cold. I suppose I'll just have to do small water changes regularly and top up with a bit of boiling water

not if you use hot and cold water to get the right temp. Mixer tap or double ended hose.....

Yeah I understand. Unfortunately I can't attach a hose to my mixer tap. Gonna have to use the outside tap and is freezing

there are quite a few different adapters available, are you sure you cant get one to fit?

I'm lucky enough to have a mixer tap but otherwise, I'd stick the bucket under the hot tap and just fill 10% of it with warm water and fill the rest with cold water then see how it feels with my pinky in comparison to the tank's temp. A one or two degree swing change will startle your fish temporarily but not enough to harm them long term. Larger swings in temperature will damage your fish. Rainfall in the wild wouldn't be 24 degrees C, it'd probably be 15 or 16, depending on what area we're looking at.

Provided I can't tell a big difference in temperature with my finger then I'd be comfortable about putting that water in the tank.

Some of what I might have said may or may not have made sense I've been at work all day and it's been sunny this evening! Been out in the garden with a nice cold glass (or two... possibly three) of Heineken

I use my electric shower.


Tom