Is there an easy way to figure variance for different game types?

[Dov]

I play in a few regular games that all have different textures.

One of them plays as follows: It's usually 10 handed with 7-8 regulars and 2 visitors. This game meets a few times/week and is super LAG. It is a 10-20, but it is not uncommon to have $600 pots. When you win in this game you will usually make at least $1500. The new guys usually lose about $500/hr. (If they're fish)

I go through huge swings in this game, and I don't really have enough recorded hours in it to calculate a solid SD. I am beating the game, but not for 1 BB/hr yet.

I know that a game like this causes these fluctuations, but I was hoping someone could help me figure out how big a bankroll would be need to play exclusively in this game.

I am currently deriving most of my income from poker and have about 6500 for a 10/20 bankroll. Lately, I've been thinking that it may not even be close to what I need for this game on a regular basis. If it's not, I will have to eliminate this game from my plan.