RO/Filter System Slowing Down (But Water Has Low PPM); Get new unit/filters or just ignore?

[BII]

A general question about RO/filter systems: Is it time to change filters or get a new unit when the filtration rate starts to slow down (enough to be noticeable), but it's still putting out low ppm water?

For ex., using a standard small (50-75 gpd) 4-stage, including RO and DI, set of filters I'm getting water at about 20 ppm. I presume that starting with perfectly good tap water at 180 and getting to 20 ppm is obviously good water. But Is there a problem that needs tending to if not getting to near zero ppm? [I presume not].

Am I correct that for our interests it's all about the ppm/low salts; that it doesn't matter what the other (1 or both solids) filters are doing or not doing?

 

[FarmerJake]

Change the filters… I used to be a water filtration technician. For drinking purposes yearly service and sanitizing of the unit was recommended but biannual would be fine in this case. If you’re seeing a reduction in production there could be a few reasons. Replacing the pre filters would be wise as the membrane that is making the RO needs a steady pressure to force both product water through and expel the waste water, so if the prefilters are slowing the feed they may be making the membrane work less efficiently.
Other components to check are
1. waste water reducer(should limit waste water to a slow trickle to enable pressure build up). This could be clogged thus not allowing waste to escape then it builds in the membrane slowing production until it eventually stops or waste bleeds to product. Find the waste line and confirm it is flowing and seems like a restricted flow
2. Check valve on the product water post membrane. As product water is produced it goes through a check valve, you will need to unscrew this and check it’s functionality
3. if there is a storage tank for product water you may have a 4way valve and both of the tank and 4-way should be checked too. Your product PPM being up at 20 indicates bleedthrough as that’s over 10% of your starting ppm and a well running small scale unit should easily hit 97% removal or better depending on brand used. If you need help trouble shooting feel free to PM me more details and I can help I’m not in the industry any more but I enjoy reliving it and making use of now useless skills

 

[BII]

Change the filters… I used to be a water filtration technician. For drinking purposes yearly service and sanitizing of the unit was recommended but biannual would be fine in this case. If you’re seeing a reduction in production there could be a few reasons. Replacing the pre filters would be wise as the membrane that is making the RO needs a steady pressure to force both product water through and expel the waste water, so if the prefilters are slowing the feed they may be making the membrane work less efficiently.
Other components to check are
1. waste water reducer(should limit waste water to a slow trickle to enable pressure build up). This could be clogged thus not allowing waste to escape then it builds in the membrane slowing production until it eventually stops or waste bleeds to product. Find the waste line and confirm it is flowing and seems like a restricted flow
2. Check valve on the product water post membrane. As product water is produced it goes through a check valve, you will need to unscrew this and check it’s functionality
3. if there is a storage tank for product water you may have a 4way valve and both of the tank and 4-way should be checked too. Your product PPM being up at 20 indicates bleedthrough as that’s over 10% of your starting ppm and a well running small scale unit should easily hit 97% removal or better depending on brand used. If you need help trouble shooting feel free to PM me more details and I can help I’m not in the industry any more but I enjoy reliving it and making use of now useless skills

Thank you very much for the detailed reply.

With seemingly most every filter component potentially having a problem to be addressed; with my unit small and cheap, readily replaceable by a unit say >$60-$80 range; and with replacing 4 filters (if I can find right replacements) independently likely costing in that range (or more?), I'm just going to buy a new unit.

Any opinions on the basic Geekpure 4-stage unit (Amazon product), which is much like what I have but with even higher capacity? Is it better to buy a filter with 5 or even more stages?

 

[FarmerJake]

It’s likely only the filters but I can understand the desire to rule it all out and buy new, getting a unit with more stages may help depending on orientation. Typically I prefer a unit with 3 prefilters, stage 1 5 micron, stage 2 granulated carbon, stage 3 block carbon, then the membrane. Stage 5 would typically be a small inline granulated carbon to buffer water before headed to a faucet but in your case the fifth stage isn’t needed. That being said a 4 stage likely only has 2 prefilter the membrane and the post filter

 

[FarmerJake]

Just clicked the link you posted, those are the t33 inline filters that have a relatively small capacity, I prefer the units with filter housings and you replace the filters but not the whole unit. These are less proprietary and you can get filters for cheaper though buying the unit is a higher cost of entry

 

[BII]

So the basic Geekpure 4-stage is acceptable, will do the job. Any opinions regarding https://www.ebay.com/itm/141725330272, and would it be better here to go with the 100 (or 75) vs. 50 unit model?

 

[FarmerJake]

The geek supply was a better setup as the 4th stage was a DI filter which will temporarily reduce the TDS even further of the product water, on the eBay one it was just a carbon filter post the membrane which is cheaper and more geared toward drinking

 

[Lil Dab]

I started out with one very similar to yours small and cheap but wasn't cost effective to replace filters. So I upgraded to this one 4 stage with Di but the DI is not needed for what we're doing. Even so this unit or better is worth getting and replacing the filters

Amazon product



If and when I buy another unit I will go with this one. It has 2 membranes and 2 carbon filters little more pricey up front but these better units come with auto shutoff when they get back pressure. You can make RO and walk away without having to worry about flooding something been there

Amazon product

 

[BII]

Thank you. I'll go with the disposable (vs. replaceable filter) Geekpure unit with it less than 1/2 the cost. With it very similar to what it is replacing, it too should last for several years for my low-volume needs. If I were also using it for drinking water, then I'd surely go with a generic cartridge-replaceable unit with higher capacity, such as those cited.

I've never had leakage, flooding, etc. with my cheap little unit. Rather failsafe, I actually just put the whole small unit and a 3 gallon container being filled in the kitchen sink, and jam a scrubbing sponge under the drain cover to make sure it can't close-off to cause a backup/flood.