thanks pal, 2 more questions!!
the ro housing ive noticed theres 2 types, the stainless one and the white plasic champ housing, which is better?
secondly the 10 or 20 inch prefilters, looking on daqua site says they need to be replaced every 20'000 litres surely your gonna go through a few of them every few weeks?
I went for 20" prefilter housings as the filters will last longer.
The 20" Fiberdyne carbon filter is good for 75,000 liters according to the suppliers spec. Doug from Daqua once posted that the chlorine content in the water will become less the further you are from the dosing station. So it could be that those filters could last even longer, but I stick with the 75k. The membrane is 5 years old next month and still performing to spec so this service schedule is working for me.
We are using less water than we did a few years ago. A few years ago there was 3 of us drawing water from the system. We were using about 26000liters of water a month through the r/o = waste and pure. As our waste to pure ratio is 1 to 1 we used about 13,000 of pure a month. (I have a water meter on the r/o.) So carbon block prefilter changes were done about every 3 months. As our water is full of sediment from time to time, I have be known to replace the sediment filter once a month.
I have a pressure gauge on each side of the prefilters. Once the gauges start to read a difference of 10psi I change the sediment filter. I'm approx 32,000 liters from the last filter change and it looks as though I will be replacing the sediment filter shortly. I also recommend clear housings - they cost slightly more but you can visually see the state of the sediment prefilter without taking the filter out to inspect it as p1w1 says.
We got a warning tag in a set of GAC filters I purchased when I first bought the 4040. The label says it had a service life of 2500 USA gallons or 10000 liters. Obviously if I used those then I would need to replace them every 10 days or so if we were still using the same amount of water as we did.