# Converting PPM to pounds of gas

#### BPKlein

##### Well-known member
Hello,

Long time lurker...first time posting. I have been using the TFP methods for 2 years now.

I am in the process of converting my 36,000 gallon in ground pool over to salt, and maybe I am overlooking some basic chemistry/math.

I know that I have seen a table that will calculate the SWG settings to give me a staring place, but I can't find it. Or, can someone give me the equation? For example.... 3ppm in 36,000 gallons equals how many pounds of chlorine gas? Then knowing the SWG output and runtime, I should be able to get pretty close.

Thank You,
Bryan

#### Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
You can actually use PoolMath in a reverse sort of way to figure it out by setting the ppm you have now and what you'd like it to be. You can also use "The effects of adding chemicals near the bottom to figure it out.

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#### BPKlein

##### Well-known member
ThankYou Bama. I had never used the "poolmath" that way. Figured I was missing something simple.

#### tim5055

Mod Squad
TFP Expert
LifeTime Supporter
I'm confused as to why you are worried about pounds of gas??

If it's to determine the size SWCG, you really don't need it. Buying a unit that produces the same amount of chlorine you are currently using will result in having a unit that is too small. You really want to look at units rated for about double the total gallons of your pool, or in your case I would say 70-80k units (or using two smaller units).

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#### BPKlein

##### Well-known member
Tim,

I have already bought the SWG. I was just trying to figure out how long to run the pump and what percentage to run it at initially.

Thankyou and sorry I didn't make that more clear.

Bryan