We installed a Spectra 280c (17 gph or 64 litres per hour) in June 2000. The smallest Spectra I know about is 8 gph or about 30 l per hour.
1- Is there better reasonable priced units available
Better is relative but Spectra makes a unit that runs efficiently and produces very clean water
(we always get less than 275 ppm of dissolved solids product water). They are expensive because they are so efficient. Efficiency is normally (here in the US) measured as litres per hour per amp and the Spectra produces about 3.7l per hour per amp at 14 V. We reliably see that kind of efficiency.
2- maintenance cost per month
I have had our 280c (two feed pumps, one Clark Pump, one 41" membrane) for 14 years and have spent about $1,500 on maintenance. During the three years we used it every day we spent about $700 on maintenance. That was primarily to rebuild
the Clark Pump. Newer models have Clark Pump parts
that last must longer.
The major maintenance cost is 20 micron and 5 micron pre-filters. In Mexico
, in pristine clean water, we replace the filters about once every three months while running the system two hours a day. In Puget Sound
when the algae was blooming in the water - we replaced those filters every other day.
I have rebuilt the following parts
over the years
Installed in June 2000
Rebuilt Clark Pump 2003 $500 (this was 1st generation Delrin pump)
Replace all hose clamps 2004 $50
Replace all feed hoses 2006 $25
New feed pump heads 2007 $250
Replaced 3 prefilter cannisters (housings) $75
Rebuilt Clark Pump 2014 $425
Replace Membrane 2014 $150
While in port and not running the system on a regular basis I run fresh water thru the system. I use an activated carbon filter to clear the fresh water of Cl (residual chlorine from the city water) and that needs to be replaced about every 1000 gallons (about every 60 weeks if you flush the system once a week)
3- Is it better to run them on Solar or Generator
Spectra was designed to run off solar. We have 500 watts of solar power and in Mexico
(20 degrees North) could run the water maker at 50 litres per hour output while using about 15 amps of 14V power.
I love my Spectra and think they are fantastic if somewhat expensive to install and maintain.