Methane Gas

We replaced our old dying water pressure tank with a new bladder type tank. Now we have very little water in the tank. I was told we have so much methane that the tank can't fill and we need some new fancy two tank system to treat the methane before it goes into the new pressure tank. Can't I just replace the new bladder type tank with the old fashion type?

If that were true, all you would have to do is "deflate" the bladder. But even the "old fashioned type" would fill up with the methane unless you have someway to "bleed" it off and get rid of it. Your diagnosis may be incorrect.

Who told you that? It doesn't make sense.

Keep in mind that a bladder tank doesn't fill up with water, the compressed air in the bladder doesn't go to zero volume. Then, what is your pump pressure switch set to? The bladder tank needs to be pre-charged to 1-2# below the low-pressure turn on point of the pump pressure control switch. To check that static pressure, you must turn off the pump, and open a faucet to relieve the water pressure in the tank, then when it is just pushing against air in the open tank, adjust the pressure, then see what happens.