Yep, you have found the "TDS inevitably rises" problem. A tank is a closed eco system. Waste inevitably collects and raises waste (organic or inorganic) that 10-20% water changes will never get rid of. Evaporation, food, substrate, rocks, plants, etc all contribute to the change in TDS. As the tank ages, you will never be able to get it back to ideal TDS level, because those minerals are used up, either by the beneficial bacteria, shrimps or plants, or dissolved solids are added from some other source.
A complete water (99%) water change is required to reset your water parameters. This is a good idea to perform a drastic water change half yearly. This reset the levels of Calcium, Magnesium, and removes any build up of unwanted minerals.
I do this every 6 months +/-. I have found this to be the ideal length of time before minerals in a closed ecosystem like a tank get completely depleted leading to moulting issues with shrimps. This big water change is when I gravel vac the substrate as well as squeeze out filter media.
BTW: 150 - 170 TDS rise in 2 weeks is normal. Time for a water change.