Can I use 10" prefilters with a 4040 machine? Also can I use my existing 80psi booster pump to up the pressure for it?
Can you use 10" filters? Yes, but if you are thinking of stripping the ones of your current r/o then the answer is no.
Your current r/o will use 1/4" plastic piping which is fine. A 4040 uses 1/2" piping as the 1/4" will not supply enough water. I'm pretty sure the 4021 also needs 1/2" piping as per Ian's advice.
A 10" prefilter has a lot of work to do processing water for a larger r/o. You won't need it to produce more water, but it will produce the same amount of water only much faster.
If you look on the Gardiner's website you will see that the 10" Fiberdyne chlorine filter they supply will remove the chlorine from 1/2 the amount of water the 40" will remove, which I guess is logical.
For me going the 10" prefilter route didn't make sense, especially with regard to the sediment filter. Between the 3 of us we used 23000 liters of tap water last month which would have probably made us 11000 litres of pure and I had to replace my sediment filter as it was so filthy it was restricting the flow of water. Had I had a 10" prefilter I would be replacing it every couple of weeks - and this has been a bad month for us weather wise.
If we carry on with our current water consumption, our 20" fiberdyn carbon block prefilter will need to be replaced every 3 months.
I love our 4040 r/o, mainly because I don't have to ration water out anymore. But on adding up the component bill 18 months ago, a DIY purpose built 4040 cost me nearly £1000.00. This includes a di vessel, wood for a cabinet, tube heater and thermostat as well as an inline tds meter. I also opted for the 20" clear prefilter housings which are more expensive and I bought 2 pressure gauges, one for before the sediment filter and the other for after the chlorine filter.
The 450 GPD unit kept up with the requirements of 2 full time cleaners, although it was tight in the winter. Our water TDS was around 255 and the menbranes brought that down to 4 without booster pump assistance. Our water pressure is between 40 and 50 psi.
More recently the area has had new pipes installed and our tap water TDS is around 115. The 450 GPD was reducing that to 2 as does the 4040 using an HF5 membrane.
We religiously changed our prefilter every 3 months and our membranes lasted 6 years. I bought the r/o second hand and it was about a year old. The prefilters hadn't been changed by the previous owner until he sold it to me, and those membranes had to be replaced within a couple of months of me buying the unit.
I bought the replacement membranes from RoMan. The 150GPD membranes were new on the market then and I had to wait for a consignment to arrive from America. In those days they advised me to only buy good quality American membranes rather than the cheaper Korean ones that were also available. They told me the Korean stuff didn't perform as efficiently as the American product did.
The prefilter have got to be replaced often.
If you estimate using 500 liters a day you will probably use about 2000 litres a week. If you have a 3 to 1 restrictor, you would have used 8000 liters to produce the pure you used. Projecting that you would have used 32000 litres a month and 256000 liters in 8 months. No way would your chlorine block filter lasted that long.
If you had been using the long lasting Fiberdyne carbon block, you would need to change it every 5 weeks on your current water useage.
What would I do? I would just replace the r/o membranes with a good quality product from GAPS, RoMan or Daqua. I would also replace the restrictor with a John Guest tap. Now I would also buy an inline tds meter and fit one sensor on the pure after the r/o but before the di vessel and then the other sensor after the di vessel. This is so I could tweek the waste through this tap to get the lowest tds through the membrane.