Thank you for the replies.
It's actually only 1/2 a gallon per minute(I wrote .5) sorry for the mix up. I was able to talk a "represenative" of the manufacturer of the water softener(a retired plumber of 32 years) and he gave me a few options. 1st, to install a check valve at softener inlet AND the thermal expansion tank at the water heater inlet.
2nd, replace my water pump with a constant pressure one.
3rd basicially disable the metered operation by lowering my hardness down to 5 and force my softener to regenerate every 3 days.
I did look over all of my plumbing and did quite a bit of testing.(I will not go into great detail here) But there is no cross connection any where. the reps opinion is: water is flowing back and forth through the softener causing the meter to change. He doesn't think the geothermal is actually pulling in any softened water because of the distant of the geo to the softener and the amount the meter is moving.
I have went with option 3 as of right now, since it was the quickest option. I am thinking about possibly getting a small inline constant water booster if I can find one and install it after my storage tank and Geo but in front of my water softener. I'm guess I will need to install a thermal expansion tank with this set up as well, but it might give me the best overall water experience at my faucets and hopefully not to much of a dent in my billfold.
Thank you all for the replies
Since you say you have to add an expansion tank, I take that to mean you don't have one now.
If that's true, have the guys suggesting you have back flow and a that a band aid sol;ution check valve is needed explain how you get back flow through the softener constantly while the geo is running. If a check valve is needed, why wasn't it installed with the geo system?
IIRC I tested the Clack meter to see if it would register a back flow by blowing on the back side of the turbine and it didn't but I could be wrong but I can say it's not easy to get a fan blade to rotate backwards, and the meter 'blade' in a Clack is a turbine type, not a paddle/water wheel type like some Fleck meters use.
The reason you haven't heard of other open loop geo systems requiring a check valve to be added after installation is because all others didn't need one or... already had one installed as part of the geo's installation or... they simply use a solenoid valve to dump the geo when its pump comes on.
I think you are getting some bad advice from guys that don't know open loop geo very well.
The constant flow/variable speed pump is an expensive and dumb idea; they don't last very long without having problems. If you want to go that route, use a Cycle Stop Valve but, that too is not going to stop back flow when the geo is dumping water back down the well. And if someone thinks the check valve will cure the problem, why are they suggesting other more expensive and intrusive solutions?
Also, you don't just change the hardness gpg to get the softener to regenerate sooner. You have to change the K of capacity (and salt dose) and/or the gallons between regenerations. And if the problem is a missing check valve why screw around with the softener regeneration schedule and use more water and salt at your expense?
You said you didn't want to get into the testing you did to see if there was a cross connection, so how about describing your set up (pics would help) and how the storage tank you mention is being used? Or by storage tank do you mean your well pump pressure tank?
You say your geo system comes off before the softener inlet... How is the geo system kept separate from the house potable water system?