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Large water change

idris

idris

Member
Joined
3 Jan 2011
Messages
816
Location
Herts
I'm about to have to do a water change of about 50%.
ie About 100 litres.
I can only get about 20 litres up to an appropriate temperature in about 12+hrs.

I am warey of having the tank significantly low on water for a week.
Any thougths on the impact or ways round it?
 
That's exactly what I do. Mix cold and hot water from the tap or boil a kettle and add hot water that way to the cold.
 
Is there a certain reason why your only using cold water and then warming it up?
as the others said, just mix hot and cold from the tap.
unless of course your using your own R.O water.
 
I have a very old hot water tank (full of scale) and am reluctant to use it for filling the tank so I use a kettle and add a dash to the mains cold in a bucket. A 100 litre change does not take that long doing this, Idris.
 
Yeah, I do it straight from the cold tap in the summer. With winter temps a 50% water change from mains water can drop the tank temp quite a bit. I add just enough boiling water to take the edge off the cold, I do not try to match tank temp with each bucket.
 
spyder said:
I do the bucket of cold and boiled kettle to make upto around 25c for shrimp tanks.

My 125 gets done straight from the cold tap. Always have done with larger tanks and no issues.
Click to expand...
Our mains water comes out of the tap at less than 17c at the moment. By my reckoning doing a 50% change with that would drop the tank from 26c to 21c or less very quickly. Which strikes me as a bad idea.

Impurities from the boiler don't concern me but the crud in the bottom of our headder tank puts me off the idea. IIRC the header feeds the hot tank but what comes out of the tap is heated by a secondary circuit, so goes nowhere near the boiler.
 
idris said:
spyder said:
I do the bucket of cold and boiled kettle to make upto around 25c for shrimp tanks.

My 125 gets done straight from the cold tap. Always have done with larger tanks and no issues.
Click to expand...
Our mains water comes out of the tap at less than 17c at the moment. By my reckoning doing a 50% change with that would drop the tank from 26c to 21c or less very quickly. Which strikes me as a bad idea.
Click to expand...

Your maths sounds about right. Depending on what species you are keeping will determine whether you want to do this or not. I don't keep any really sensitive species so I do it and get away with it. The water is trickled in slow around the heater. Thinking about it, I often watch the fish dashing in and out of the cool flow as if they enjoy it.

Incidentally, a temperature drop like that can trigger spawning behaviour in certain species so it's not something I would consider bad.
 
idris said:
Our mains water comes out of the tap at less than 17c at the moment. By my reckoning doing a 50% change with that would drop the tank from 26c to 21c or less very quickly. Which strikes me as a bad idea.
Click to expand...

The maths is spot on, in theory with 17 goin in, youd end up with equillibrium at 21.5, so maybe you could do it more progressively if its a concern, or warm it up a little to prevent as much of a drop
 
The thermometer I've used on the tap water only starts at 17. I don't know how far bellow that the water actually is. It is pretty refreshing when I brus my teeth ;)

I've steered clear of the the kettle as I can see the copper on my kettle element and as I've gor shrimp I'm a bit cautious.
 
PeteA said:
Or get hold of a cheap internal heater?
My biggest problem is finding somewhere in the house to store 100 litres of water in the first place :D
Click to expand...
That's what I do, but it takes ages to get anywhere near tank temp in the garage.
 
LOL! I get each bucket to temp using hot and cold water from the tap. I always though just putting in cold water would be BAD. Might have to rethink this though as it would make life a whole lot easier!! I change 30% of the 450l every week, 50% of the 180l and 20-25% on the 125l and 2 60l tanks. What do you do about dechlorinating the water you're putting in?

Viv
 
Viv said:
LOL! I get each bucket to temp using hot and cold water from the tap. I always though just putting in cold water would be BAD. Might have to rethink this though as it would make life a whole lot easier!! I change 30% of the 450l every week, 50% of the 180l and 20-25% on the 125l and 2 60l tanks. What do you do about dechlorinating the water you're putting in?

Viv
Click to expand...

I use API and dose straight into the tank whilst filling from the hose. Dose the full capacity and not just the amount changed. 60l and under gets bucket procedure.
 
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