Trying out a Technopool-
After a bit of study on these forums, I got an Aqua Technopool Rx+pH model, and have had it in operation for a week or so. I used XETrade to send a wire transfer after getting a quote with Aqua Italy; even today sending money internationally is like watching your treasure galleon sail off into a storm. I made a separate manifold from 1.5in PVC, since my old filter is a marvel of compact inaccessible plumbing. The 50mm saddle adapters supplied with the unit fit this O.D., and you could also use compression fittings (use two O-rings in place of the metal ring!) if you drill out the stop to pass the probe through. The unit was not much more than the cost of a couple of bare peristaltic pumps, mid-$700s including shipping at 1.45 $/euro. I pondered the ongoing expense of having to get spare probes, tubing & etc internationally from Aqua, but lots of sources here like Omega have replacements (take heart, Simpool owners). The pH and Rx (ORP) probes seem to be standard 12mm, and are $30-$50 each. The Santoprene pump tubing is also available for around $1/ft. I can probably reuse the pump end fittings, or just leave them off. The unit also has a dose-vs-temperature correction feature for which I would have bought the optional Aqua probe if our communication had been a bit better. Instead I just bought an Omega version (100 ohm platinum RTD) for $40. The unit is well-built, in a watertight box with access for adding relays, level sensors, etc. I let it slurp diluted bleach and acid from a couple of gallon jugs for now. It has programmable limits, delays, alarms and setpoints galore, but I just set it for 675mV ORP and 7.5 pH and it has held each to within a percent. It powers on when my pump does, and can (again programmably) stabilize for a time before dosing. The home brewing and aquarium hobby sites also have lots of info on probes, tubing, etc. Aqua is good to work with and their prices reasonable (esp. with no VAT), but their UPS shipping was over $100. I'll work hard to avoid that unless I have a repair or [2 yr] warranty issue.