[mike31154]

Sounds like you've made a great choice based on your research. Before this thread fades into the archives I thought I'd just mention that I find it useful to have two pressure guages plumbed into my RODI system, one before the RO membrane (generally the config with most systems offered with that option), the other right at the input. This allows me to monitor the pressure differential between the two and has proven a great way to determine the state/life of the pre filters. For the price of another psi guage, I've found it a worthwile addition.

Most recommendations I've seen on forums & from system vendors are to change the poly pre filters as well as carbon stages at certain time based intervals such as 6 months. While I'm not a RODI expert, this type of time based maintenance makes no sense to me. Logic tells me that I should be basing system maintenance on gallons throughput and this varies for everyone I'm sure. Yes, prefilters are inexpensive, but why not get full use out of them by monitoring parameters such as pressure differential & number of gallons produced? The clear filter housings are a good indicator of when pre filters need some TLC, but I believe the more reliable method is a dual pressure guage set up.

While my water provider maintains a generally reliable & constant pressure, there are minor fluctuations from time to time and with a single pressure guage, I may be inclined to think the system needs maintenance. Having two pressure guages helps mitigate that issue. With clean pre filters the pressure differential on my set up is between 18 & 20 psi, eg, guage 1 reads 86 psi & guage 2 reads 68 for a differential (pressure drop) of 18 psi between the input & the RO membrane. When this number approaches 22 psi, I know it's time to service the 5 micron poly pre filter. I've actually found taking it out, scrubbing the exterior and putting it back in restores performance to near new. Most of the grunge causing the pressure drop collects on the outer surface of the pre filter in my situation. When my 5 stage system was delivered it came configured with 5 micron poly pre filter, the 0.5 micron carbon chlorine guzzler, 1 micron carbon block, 75 gpd RO membrane & DI stage. After about a year of usage & monitoring I've removed the second carbon stage (not required since provider uses chlorine, not chloramine). Also moved the 0.5 micron carbon to stage 3 and added a 1 micron poly to stage 2. This configuration has been working great for me, YMMV.

I've added a worksheet to my Marine Aquarium Excel spreadsheet to track RODI system parameters, including gallons of water produced. It's been a great tool in maintaining the system. Better than two years running now and still on original DI media as well as carbon block & membrane. The 0.5 micron carbon block in my system is a rated for 20,000 gallons throughput at 1 gpm, so this is another instance where keeping track of your throughput comes in handy. I hightly doubt that most hobbyists produce that much water in 6 months, so why replace it at that interval? I've purchased a pool test kit which can measure chlorine & intend to test the water after carbon block soon though, just to ensure it's still pulling out the nasty stuff.

Finally (whew, turned into a bit of a novel here), having the drinking water option is a great idea. In Vernon I'm on the Kalamalka Lake source and we've been under a boil water notice since early September. This hasn't happened very often but being able to produce safe drinking water with my own system is coming in real handy right about now. Wine & beer making with concentrate is another activity that benefits from the pure water I'm able to make. Cheers.