Why does the amount of sats in a lightning payment channel amounts vary if no txns are occuring?

Question

I recently got my lightning node up and running (went the easy route via Casa node). I noticed that I was having a difficult time tracking the amount of sats in a given channel..I wasn't doing any transactions with them, but they seemed to vary up and down 1000 sats up, 2000 down, etc.

Confused, I finally opened up a payment channel only to watch it, see how it moves, with a nice round number: 1,000,000 satoshis.

It's still in pending state (trying to open it up with ACINQ node for little miner money, still hasn't been picked up by a btc miner)...anyways..it's still in pending state, but the amount now lists "989,869 sats Pending" not 1 million sats as I tried to open the channel with. . .

Should'nt satoshi quantity stay the same for a given channel (if it's all opened up and no txns are occuring, or if as in my case it's in pending state?). Does the bitcoin price going up or down affect the amount of btc/satoshis in a channel?

Answer 1

Without detailed log files I can only guess the exact reason why you see this behavior. Two likely things come to my mind:

1.) Your node might have routed smaller payments. So in case you have outgoing capacity on one channel and incoming on another one someone might have used that to rout a payment. which would move some satoshi from one channel to the other

2.) If you opened the channels you are responsible for paying the fees in the case of a force close. These fees are taken away from the amount of satoshis which you own in your channel. Everytime you make a channel update (for example with a routing attampt - even if routing was not successfull) the fee estimator of your node and your peer try to estimate the onchain fees that your node would have to pay in case of a close.

Since your node seems to be fairly new and since the onchain fees have been fluctuating a lot recently I am almost certain that my second guess is the reason for the behavior that you observed.