The Value Of Used Water

[weezawoo]

I am getting a new tank tomorrow and it is 300l. My current tank is 200l. I have to move my fish straight over to the new tank due to space. I am using filters on the new tank with bacteria already etc. My question is, is there any benefit in me taking the water out of my old tank and put it in the new one or should i just use fresh treated water?

 

[elisew]

I found it easier to transfer everything from my 180L to the 380L in one go, including the water which I then topped up with fresh water. At least that way you can continue without messing up your filter bacteria

 

[KittyKat]

Mainly the value in taking the old water would be if the parameters are significantly different from your tap water.

 

[fishnovice]

I generally add some of the old water when setting up new tanks or overhauling existing ones as 100% new water might be too much of a shock for the fish

 

[Gilli]

When I bought a bigger tank I used it as an opportunity to have everything new and clean. Put fish & plants & ran the filters and heaters all in in a large tub for the day, drained the old tank washed the gravel and filled up the new tank with fresh water. It didnt do my fish any harm and didnt get any blimps in my water stats.

 

[Inchworm]

When I clean out a tank I like to use about 1/3 old water and the rest fresh, dechlorinated water. It seems to me that it gets off to a good start more quickly. I've also noticed that it gets fewer bubbles forming on the surfaces and that nusiance is over faster.