Thanks J, i was also doing some reading on RC and here is one of the links i found (if anyone else needs help, good reading too)
http://reefcentral.com/modules.php?s=&name=Content&pa=showpage&pid=2
and here are some answers i got from A.J. on reefcentral
1. If you lessen the waste flow you run the risk of not providing enough flush water for your membnane and it will drastically reduce its useful life.
2. By allowing more waste flow you extend the life of the membrane as it stays flushed out well. You can go too far though and waste so much it reduces the pressure on the membrane so it doesn't produce enough water. The optimal waste to good ratio is somewhere around 4:1 to a little more. I run my RO waste at 6:1. This is easily measured with a measuring cup and a wristwatch. First time how much good water you RO produces in a timed period, 3 to 5 minutes is sufficient time. (If you have a pressure tank,disconnect it first or run water until it is empty and time only the flow from the RO). Then fill the cup with the waste flow for the same period of time. The waste amount should be about 4 or 5 times as much as the good amount if it is working properly. I am not a fan of adjustable flow restrictors, I like a fixed orfice so it always remains the same and you can't mess it up.
3. The limiting factors are incoming pressure, water temperature and raw water quality. A good RO membrane like a 75 GPD Dow Filmtec is designed to operate best at 50 psi, 77 degrees F and 250 ppm TDS raw water. Any change in these 3 things affects the output either up or down. Temperature and pressure have the greatest effects. Look here and you will see:
http://www.dow.com/webapps/include/...10.pdf&pdf=true
4. The best waste to product ratio is 4:1 to 6:1. 98% rejection means it removes 98% of the contaminants in the water, not how many gallons. It wastes 4 gallons for every 1 good gallon it produces. The waste is still good water for washing clothes or watering your trees with though so it doesn't have to go down the drain if you have a use for it.
5.( EDIT- I see you have an inline meter) You really need a TDS meter or conductivity meter if you have an RO/DI. Handheld TDS meters are $25 all over. You first test your raw water to see what the incoming TDS is, next test the RO only without DI, it should be removing 90 to 98% of what the raw water TDS is depending on what membrane you have(more on this later). Lastly test the RO/DI product water and it should read 0 to no more than about 3 TDS. Any more than 3 and you begin to leach contaminants back into your ultrapure water so change your DI. Pre filters and carbons should always be changed every 6 months, no exceptions as you can grow bacteria in old filters and its not worth the risk for a few dollars worth of filters. You can also get a pressure gauge and test the pressure drop between the incoming house pressure and after the prefilter. When you see a 5 lb or more drop change the pre and carbon filters.
6. As said before you need 50 psi if it is a Dow Filmtec membrane and 65 psi if it is a GE Water or Applied Membranes membrane. I am a huge fan of the Dow membranes for that reason. Most of us don't have 65 psi in our homes so the other brands have inflated production numbers you will never get. A 110 lb pressure gauge and hose bib adapter should be about $8 at Home Depot
7. Use the measuring cup and set it at 4:1 to 6:1 and leave it there.
8. Increasing pressure is a good thing, but don't go over 80 psi or you risk messing up plumbing fixtures in your home. Heating the water is a risky thing to do as membranes can't stand water over 120 or it will melt them. Its not worth the risk.
9. Now the nitty gritty: If you have a 100 GPD filter odds are you do not have a true RO membrane but instead have a 90% efficient nano filter which is not the same thing. Even Dows 100 GPD is a nanofilter and not a RO. The best membrane sold today is the Dow Filmtec 75 GPD 98% rejection rate true RO, hands down no questions. By switching to that you will not have to raise your pressure as high if at all and you will get better quality water. You will also find your DI resin will last 4 times as long as with a 90% rejection membrane. Thats a fact.
Hope this helps!
A.J.
thanks again J.