Buckeye Field Supply

RO water doesn't have low pH...

I answered your original question. If you are asking if they are all the same size, then nearly all the membranes you see are called "1812" membranes - meaning 1.8" in diameter and 12" long - all thes will fit in the same RO membrane housing. If you are asking about performance - then no, they are not the same. Check the manufacturer's specifications for the feedwater pressure and you'll see one brand, Filmtec, is spec'ed at 50 psi. Other brands are spec'ed at 60 or 65 psi. For some brands at some vendors, usually very low cost imports sold on the auction website, there are no specs provided, no brand name, and you have no idea what you're buying. Russ

If it were chloramines you should be seeing it right away in your DI water. It's the carbon exposure that splits the chloramine - the ammonia is removed a bit by the RO membrane, but more by the DI resin. Russ

No, all membranes are definitely not the same. If low cost of initial purchase is your only goal, I think you went to the right place.

That "500" means 500 ml/minute. If you have factory spec conditions, that flow restrictor will yield a 2.5 to 1, rather than the appropriate 4:1 ratio. We're finding that many of the cut rate (ebay) systems are coming with the wrong flow restrictors installed. If that ratio of waste water to purified water is too low, you'll shorten the useable life of the RO membrane. Russ

Do you use a refillable DI cartridge?

If you have factory spec conditions, that flow restrictor will yield a 2.28 to 1, rather than the appropriate 4:1 ratio. Russ

Ciao - did you get that system squared away? Russ

Kshack - good advice! Russ

When ASOV's don't work, its often a problem with a leaking valve at the end of the DI "out" tube, or at the check valve between the RO permeate port and the low pressure "in" port on the ASOV. Just sometimes... it is the ASOV itself. If your DI stage doesn't fill up, you just have some air trapped in there. To purge it: With the system running, and with a towel handy, unscrew the DI housing about a quarter turn - just enough to break the seal. You'll see the water level start to climb right away - just before it reaches the oring at the top of the housing, tighten the housing back up an you are good to go. Russ

We hear this a lot, and have to respectfully disagree. Many of the components look similar, but over the last 10 years of building these systems - there is a fair amount of difference if you know what you are looking for. For example - we can get chear RO membrane housings than we do, but they tend to develop internal cracks. We can get cheaper filter housings, but they to have a tendancy to crack. We use rivets for instance in some places where we could use a sheet metal screw instead - this would be a distinction that is probably meaningless to you untill you catch a knuckle on one of those exposed screws. We could use cheaper fittings - they look similar - but the quality is lower and they tend to leak and the valves break. We could use steel brackets - they look similar, and are less expensive for use to buy - but they will rust. We could screw our pressure gauges into the tail end of the RO membrane housing, but you won't get an accurate reading that way. The list goes on... Bottom line - the "skeletons" of these systems often look similar, but that doesn't always equate to similar quality. Russ

Some things to look for in a good system for this hobby: Standard-sized prefilters, membrane, and DI cartridge Brand name, high-rejection membrane Specifications provided for each stage Pressure gauge after the prefilters and before the membrane Thermometer DI bypass Vertical DI stage Refillable DI cartridge Aluminum bracket Quick connect fittings Flush valve Clear housings High-quality instructions Customer support before, during, and after your purchase A vendor involved in your hobby Russ

If you still need help troubleshooting the system we'd be happy to help you! Russ

We are a little biased on this issue... Russ

Especially in cases where folks don't want to make permanant changes to the plumbing - these are easy and quick to install: We try to encourage people to use a method other than those self-piercing needle valves. Russ