New bloke makes cider for 1st time

Hi. New to home brew and have aquired some apples from a friends tree. I used a standard juicer to extract the juice and have transferred to a demijohn. However, due to using a juicer I think the juice contains quite a lot of frothy pulp. There is quite a lot of matter at the bottom and top of demijohn. I am thinking of syphoning off the juice in between to a clean DJ. I have added a campden tab to prevent fermentation at this stage as I will be adding cider yeast shortly...
The question is...when I have transeferred to clean DJ should I top it up (as I understand it should be full up) with water or apple juice from a carton?

Welcome to HBT!

How much volume is in the demijohn?

My brewing is structured around 5 gallons. Sometimes I end up with less or more which equates to a bottle more or less.

I do not top off with anything after primary fermentation unless it's a cup of brewed spices or something.

Thanks for the reply. The demijohn (minus the sludge) is around 3/4 full of actual clear juice.

Should I bother syphoning off at this stage or will the fermentation process break this down anyway.

I was under the impresssion you should always fill the DJ up or risk manking vinegar?

It is good to keep the demijohn full. You could let it ferment with the sludge then rack and top it up with AJ after a week or so.

Ok, so have gone ahead strated fermenting the juice and sludge. Actually there seemed to be more volume of juice than it first appeared and the demijohn is nearly full.

After adding 1 teaspoon of cider yeast it has been fermenting for 5 days now. It is really active and bubbling away. I read that perhaps I should be racking off to another DJ after a week or so, but I'm assuming that I should wait until it stops bubbling before doing this?

Having read some posts on here I'm now slightly worried that most recipes contain some form of sugar or honey and my recipe contains well, just juice. I think my cider may be in keeping with er more traditional english scrumpy types Oh well, it's a steep learning curve for me, but my fingers are crossed for something drinkable.

Recipes with sugar are usually for storebought juice. Fresh pressed juice is usually fine by itself, thats the way its been done for thousands of years. Racking is optional, partly it depends if you intend to carbonate. If you want still cider it may be better to rack and clear the cider.

Ah great thanks. I wasn't planning on carbonating, so can I rack directly to bottles?

If you don't want carbonation you want the cider to clear before bottling. Racking to a secondary container after primary fermentation has finished gets the cider off the lees so you can give it time to clear, and is also a good time to add another dose of camden to protect against infection.
If you don't mind a slight deposit in the bottle, you can just bottle straight from primary after a month or so, and add camden just before bottling. It comes down to how fussy you are, and how long you intend to age for.

Great advice. Thanks. I have a second demijohn, so may as well transfer to this after a month or so and add another campden tablet at this stage...

I would not rack into another container until two weeks of primary fermentation. Ciders take a little longer and you do want the yeast to do what they do so well.
Then I would rack to the secondary and forget about it for a couple of months and then bottle. You can distract yourself by starting another batch right a way.