When I asked for a quote and about the need (or otherwise) for a pressure booster pump, "The Waterboy", Marco Justino, based in Durban, said that this was not required as long as the incoming water pressure was over 3 bar.
I said I'd try and figure out a way of measuring the water pressure here and get back to him.
I spent a frustrating 30 minutes or so going around all the places that might conceivably have a pool filter pressure gauge. None did, not even the pool shop. Eventually, I thought laterally and wondered if I might persuade a car oil pressure gauge to work (at least briefly); a quick trip to Midas and R90 later, I had a gauge that could read up to about 7 bar. A few Gardena hose fittings on top, and I had what I hoped would be a workable water pressure gauge.
|Oil pressure gauge and Gardena fitting|
|Conveniently, one of the fittings that came with the oil pressure gauge happened to be just about the right size to self-tap into the plastic of the Gardena fitting. Yay!|
|Ooer, it actually works!|
So it looks like there's enough pressure for RO, yay, which saves about R800 on a booster pump. Still, given the fairly high TDS/EC, I wonder if a higher pressure might not be needed to force that water across a membrane?
Incidentally, I tested (pre calibration) the Oasis ozonated water available from the Oasis filtered water shop here, and it has an EC of about 8 - which will do for now. And at R4.50 for 5 litres, is a whole lot more affordable than R37.15 for 5l, or R13.75 for 1l that pharmaceutical grade distilled water costs!
Of course, I imagine that water and oil pressure gauges are not happy buddies, and I doubt that gauge will work again once its insides corrode...