So, when the TDS starts to go up, are all filters changed at the same time? (Meo, another hijack but you did say you don't mind sharing
)
When mine hit 1, I ordered the replacement filters and was planning on changing them all this weekend. The replacement filters were a total cost of $65 (I have a 4 stage) so I look at it as cheaper to replace them all than to have to replace anything in any of my tanks.
FYI Meo, my tapwater TDS is around 260.