You do need to top up the demijohn.
Adding water will dilute the wine.
How much wine are you making?
What size carboys/bottles (demijohns) do you have?

It's best to have an assortment of bottle sizes so you don't face the
problem of topping up with another wine. In our local amateur wine
contest many fruit winemakers add grape wine. This always knocks down their
score because it dilutes and changes the fruit character of the original
wine. So, if you don't have an assortment of bottles, so you can avoid
topping up, buy some commercial plum wine and use that to top up. Any other
wine will change the character of your homemade plum wine.

Bill Frazier
Olathe, Kansas USA

"Alex" > wrote in message
...
> Hi Again
> further to the helpful advice given by this group a short time ago, I have
> had my wine in secondary fermentation for three weeks, my wine is making
> around one bubble
> every few minutes. Assuming when I take a hydrometer reading it is 1000 I
am
> going to rack into a clean demijon.
> Do I need to top up the demijon? I have heard that you can use a simular
> wine, as I do not have any I would have to use water? Is this ok or will
it
> dilute the wine?
>
>
> Thanks Alex K
>
>
>
>
>