Hi Everyone, Most RO unit ratings are based on the following baseline data: 500 ppm Total Dissolved Solids in the water ie. The more solids in the water the higher the pure/waste water ratio is. 77F source water tempurature ie. the high the tempurature the more productive the RO membrane is. 60psi water pressure. ie. The higher the water pressure....... the more water can be produced. Three factors effect the production of RO water: 1. Total Organic & Inorganic material in the source water. You can't really change this (thats why you are using an RO unit) 2. Source Water Pressure You can buy pressure pumps (both Kent & SpectraPure make one) to increase the water pressure. Most water pressure (at least in major citys) is 60 PSI. The minimum PSI to operate an RO unit is 45 PSI. 3. Source Water Tempurature. The lower the tempurature of the source water, the lower the production rate of the unit. Here is an idea I got from one of my Marine Aquarium Mailing lists about how to increase [see e-mails below] the production of my RO unit. Also included is an e-mail response from Spectra Pure about heating the source water before it gets to the RO unit. This will increase the water produced by RO units with little degrade in quality. I hope this helps. Cheers, Victor Eng Vancouver, BC, Canada email@example.com ======================== [Spectrapure Response] Thanks for sharing the idea. We have heard of several similar solutions, including ( After doing what you have done) returning the waste water to the container to capture more of the BTU's. The Purity will drop ever so slightly, less than 1% [My E-mail] Hi, My ro unit is not producing the rated gpd that is specified. I know that the production rate is depended on three things: 1. water temp. 2. water pressure and 3. solids in the water. The water pressure is strong (65 psi) and the solids are actually very low (40 ppm), so the only thing that could be causing my lower production rate is the low water tempurature of the feed water (around 45 degrees). I recieved this idea from one of my reef lists to increase the water production of my ro unit: 'I came across a neat strategy for increasing the output of RO units, and I thought I'd pass it on. Tell me if you've heard this one before. Take a 5 gallon bucket, fill it with warm water (or toss in a heater), and run about 50 feet of high pressure turbing from the spigot to the RO unit - coil the 50 ft. length into the bucket of warm water. Voila - a heat exchanger. Around here where the water is about 45 degrees at 80 psi, this trick tripled my output...' I was just wondering if the quality of the water produced would decrease with the increase in water tempurature. Any information that you could give me would be appreciated. Thanks. ------------------------------------------------------------------------- This is the apistogramma mailing list, firstname.lastname@example.org. For instructions on how to subscribe or unsubscribe or get help, email email@example.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!