How to fix too tart cider?
 

I just tasted my first cider, and used martinellis and santa cruz (it was very cloudy and had a lot of sediment, but was pastuerized), a few tea bags, and some lime juice, it tasted a little rotten, and too tart. I have fermented for a month, the gravity is down to 1.01. Is there any way to sweeten it up before bottling? Any ideas about why it might have that smell?

The smell was possbly from fermentation. The yeast may have got stressed at some point and started producing sulfur. If you leave it a bit before bottling it should disperse eventually.

As for reducing the tart taste, I'm not sure. I'd be interested in knowing that too.

You should measure the pH and if possible the Titrateable Acidity (TA). If the cider is very acidic, eg below 3.2 pH then you can try to lower the acidity. If the pH is normal there may be other issues.

to add sweetness just throw in a can of apple concentrate or two

Any tips on lowering the acidity?

Calcium carbonate.
Potassium carbonate
Sodium carbonate
Sodium bicarbonate

All at food grade or better. Try a pint first then scale up. I guess you have no idea on pH other than tastes nasty.

If I want it drinkable quickly I will add some unfermented cider or concentrate, however its my experience that the tartness will naturally subside with age. My first few ciders I was really disheartened until I let them age out a bit because of the tartness. They were completely different tasting after a couple months.

If you do sweeten it up, just make sure you pasteurize or store it cold so there are no bottle bombs.

I would think the lime juice contributed to the tart taste as well, although I haven't ever tried brewing with it so I don't have personal experience.

Good luck!

why lime juice?

lime juice does not keep very well in any capacity. it gets pretty funky pretty quick.

Time will smooth out most tart ciders, I tend to leave mine up to three months if they are very tart on the tast tests.

Great advice! A couple of responses, I do not know the pH, how do you even test this?
I am typically a beer brewer, but had a dry English cider and really wanted to make one. The lime juice was a part of a recipe I found on the home brew forum, I used it because it seemed like it would keep the cider from going sweet which I am not a fan of.
Finally, it is tart, but seems to have a bit of a rotten aftertaste. Is that normal? I have no problem letting it ferment for as long as it takes, I do beers some times for 6 months plus. I just don't want to waste carboy space if it is going to flop.
One more thing, what temp should I ferment at if I do let it go for a few more months?