Out toilet in our apartment is draining sluggish. With a glove on I put my fingers in the small hole in the toilet - the syphon jet - and it has a bunch of calcium buildup.

I was able to take an allan key and open the syphon jets at the top of the bowl but I couldn't get much of the big buildup loose at the syphon jet at the bottom.

My thinking was to turn the water off and use a pump to remove all the water and pour a solution into the bowl to sit overnight. My question is: What solution would be best? CLR: Calcium Lime and Rust?

Do you have another suggestion as to how to break up the deposits?

 

Yes as you stated. All good choices.

 

Vinegar will also work.

I would also shut the water off to the toilet flush and then pour some of whatever you use into the tank drain and overflow..
I would do this every hour or so if you can without refilling the tank.