My Betta Fish/ Warm tank

Question
I have a Betta Fish in a one litre glass tank. I have a thermometer in his tank, and it says it is only 10 degrees celcius. Most people suggest between 21 and 27 degrees. Do you have any tips on how to keep his tank warm? I have it on the opposite side of the room from the window and have a blanket wrapped around the sides of the tank, but the temperature doesn't change.
Also, I hear the betta make a bubble nest when it's happy, he's not making a bubble nest anymore and he used to. Do you think this is because of the cold water? Or are there any other things you think could be causing it? I am feeding him 3 pellets of Hikari Betta Bio-Gold baby pellet food. And wash his tank once every 1-2 weeks. And I use 1 cap ful of Aqua PLus tap water conditionner every time I wash it. I'm not sure what else I can do, and just want to take good care of him. Please let me know any ideas of how to keep his tank warm, and of anything I might be doing wrong (not enough food, too much food) to make him not make a bubble nest.
He is also 2 and a half years old, so I know he is fairly old for a fish, but I want to keep him as long as possible happy and healthy! :)
Thanks so much for your time!

Answer
Hi Gridelly,
I wish I could help you, but the fact is, the only way to keep a betta in warm temperature is to have him in a big enough tank where we can put a thermonstat.  Never put in too much conditioner, this is not good for your Betta.  In a one litre tank, only 1/4 conditioner should be used.  It is normal for a Betta to blow their nest, and when they stop making their bubble nest it is because something is very wrong.  Cold water is a reason.  Small tanks are another reason.  I am going to write down information on the Betta, so that you can understand him better.  When we buy bettas we often get bad advice, or none at all.

Here is how a Betta should be treated:
 


A betta needs 5 gallons of water to be healthy, and happy.
In their habitat the betta may live in shallow waters, but they have lots of room to swim.  
Keeping Bettas in small bowls, containers, vases etc, is cruel.  The Betta is one of the most mistreated fish on the market.
They need a heated tank.  Temperature should be 80-82 degrees.  They are tropical fish, and are cold under this temperature.  Cold bettas get sick, are miserable, and live unhappy lives. ( Always remember  when heating a tank, do this very very slowly..1 (one) degree every two days, as bringing up the temperature too fast would kill your Betta.)  The temperature should always be stable.  Fluctuating temperature is very bad for bettas, and any other fish.  
They should have a silk plant in their tanks, so that they can rest on the leaves  They also need a little tunnel or some knick knack that they can go through.   One teaspoon to five gallons of diluted aquarium salt may be added to his water, when a Betta is well.  
Aquarium salt helps them with stress, and also helps with parasites.  However, if a Betta is showing signs of a swollen tummy, salt should not be used.
They need a varied diet. This is very important.  Betta pellets one day, Betta Flakes the next, Daphnia the next, and bloodworms should be given once a week as a treat.
He should be given one well cooked frozen cooked pea a week, and on the day you give him the pea, he should fast.    
A betta is prone to constipation, and constipation leads to Swim Bladder Disease.  A frozen cooked pea a week keeps them from getting constipated.  Always remove the outer layer of the pea, and cut it into small pieces feeding it to your betta one piece at a time.
They should have 2-3 small meals a day, and not one big meal.  We must remember that their tummy is the size of their eye.
Example:  2 pellets for one meal.
Water changes are very important.  Water changes must be made every week without fail with a good water conditioner such as Aqua Safe or Stress Coat.  There is also a conditioner made especially for bettas.   Never put two bettas in the same tank, they will kill each other...male or female.  The Betta male is a loner.  Females can be kept together in a big enough tank.
When treated well, a betta can live up to 8 years, if you buy him when he is very young.  (Unfortunately we do not know their age when we buy them at the Pet Store which is why some bettas die two or three years after we have bought them.
He's an intelligent little fish, and should be treated with kindness.
Too many vendors know nothing about the betta, and don't care...so don't give good information on how to keep them.
They are there to sell, and will say anything just to make a buck.  They send you home with your bought betta, telling you a small bowl is perfect, and bloodworms!  The poor customer thinks he has everything he/she needs, and then the fish gets sick, money is spent to cure him, and eventually the fish dies.   
This turns my stomach over.  Unfortunately there are no laws to protect fish.  
Bettas kept in small bowls, one gallon tanks, and vases, will get sick, and are very hard to cure in such little water.  They end up dying, and
that hurts the person who has grown so attached to them.  They don't deserve to be treated this way.
This is how a Betta should be treated.  If treated this way, you will have your friend for a long long time.  I have bred them, love them, and know what is good for them.  If you have anymore questions, feel free to contact me anytime.
Lynda