A question for the plumbing gurus

This is for me, not an inspection, but I need help! Here is the info, I have a 240 ft well, 1 hp 10 gpm pump, check valve installed 1ft above the pump. There is 85 ft of 1 inch line to the house, pressure tank with a 40 60 switch, this all goes to a GE whole house filter that uses a 4 stage media filter system. Approx. 5 ft before the pressure tank there is a 1 inch line teed into the system that feeds my quest house which has its own smaller cartridge filter system. Because my check valve is at the pump the whole system is controlled by the 40 60 switch and it works great.
Here is the problem, when water is run in the guest house I think it is causing a back siphon on my whole house filter due to the fact that my house water suddenly becomes “dirty”. I think it is basically creating a backwash condition and stirring up the filter media. I have thought about putting a check valve in the line after the switch but before the filter to stop the siphon effect. However I am thinking that I may end up with an over pressure situation in the main house plumbing due to the 2nd valve.
I don’t want to feed the quest house through the big filter because I also use the line to irriagate and the filter is a set life by gallons type.
Any ideas would be a great help.

Do you think a anti- siphon valve may help ?

Is that the same as a 1 way check valve? I worry that because the pump is able to go to 100 psi that a check valve will end up over pressuring everything beyond it when the pump is running.

I checked out an anti siphon valve on line. It seems that it might fit my needs, but I still welcome any ideas.
Thanks Roy, if you ever want to build a log home contact me!

A dual check continuous pressure backflow preventer should do the trick for you. You can get one for 1/2" or 3/4" line rated up to 175psi for about $50. I would put one on both the main house and the guest house line to prevent problems on either line.

Thanks for the ideas, I am going to install backflow preventer next week, I will let you know how it works. If you ever get to the backwoods look me up, the beer is always cold.