On this design, anti-scalant with silica sequestrant made sense. We are using Ozone for oxidizing iron, manganese and H2s in the first atmospheric tank, cleaning it up with KL, DAB as the pre-boost to the main RO, Calcite remineralzing, atmospheric storage, UV post... lots more not shown here but you get the idea. We even got the county to agree to a "French style drain" as shown in the drawing by the gravel for the RO and KL waste. it is in the middle of the forest...
DAB has been a huge hit for us, we bring them in by the truckload and they have replaced the majority of our other pumps. Their ability to handle low to high flow without a problem has been a huge benefit to us. The main drawback is that the large DAB is a bit expensive, but considering what you get for the money it is not too bad. Also they are butchered online so many companies don't want them. People need to make a few bucks, and when they are selling for 10% over cost online, people expect you to match the price... this does not keep the kids fed or the lights on. Some of my larger customers simply "give them away" at barely above cost, basically a loss leader since they like the pumps so much. Many companies are finally getting wise to the online resellers, usually some guy in his moms basement smoking weed selling candles, fidget spinners, water filters etc... then they complain because they can't pay their bills working on 10% margins... and with shipping cost going up as much as they have this year... we are seeing a lot of changes, mostly for the good. Several companies are also enacting MAP contracts and cutting off companies that don't take care of the customer support after the sale.
I run projections for the membranes all the time to see what in theory will happen and what kind of efficiencies I can hope for. here is a recent one where we could only get 25% recovery with any membrane longevity. Ro under the sink is excellent but you have to let the customers know reasonable expectations. TDS in excess of 1500 PPM for under the sink should be designed with a little more care. over 3000, a lot needs to be taken into consideration.