I have clear water lines from the city water to a 20 micron
whole house filter to sediment/carbon/RO/DI/carbon to
storage tanks. No matter what I do, algae grows in the lines.
The sediment level in the water is about 2 ppm, incoming is 300 ppm, so I know my filter system is working. I have changed everything, and the problem always comes back. I have been told that using non-clear lines will block the light and kill the algae - but I wonder - why does only the filtered water grow algae - I guess it's because the clorine is gone?

 

Are the storage tanks atmosphere or pressure? I've always chlorinated after the ro on atmosphere tanks. Then dechlorinate at point of entry. To control the algae, you might want to chlorinate.

 

Thanks, but I'm just curious, I've tried UV light in the lines, and have 3 sediment - 20, 10, and 5 micron, and 3 carbon filters, the RO filter, a DI filter, and my tanks are pressurized. I just don't understand how clean water can contain spores that cause algae to grow?

 

The only factors I can see are the fact that you are using clear lines and don't know if the system was disinfected prior to using.

 

Thanks, but I did replace every single part, and with clear lines, algae always grows - I know not having clear lines means less algea -but I still wonder how it grows in perfectly clean water - except the chlorine is gone. Glad I found this forum to chat about such things with you guys!

 

I wondered the same thing. It's a sealed system. How was it introducted? You could try disinfecting the whole system to see if it comes back.

 

Unless you are killing the spores the bacteria/mold will grow once it gets light. Chlorine or UV light will take care of this.

 

Thanks, I also want to tell people not to put in a DI filter - they don't last long and generate lots of junk in the lines.

 

I talked to a water filter/softener pro today, he said UV filters kill algae at the point of exposure - but with light, algae grows after UV filters, Amazing. I sure hope algae that grows inside very clean water that has no chlorine - is safe!

 

Sounds like he needs to take some more UV classes. UV will kill everything in the water if the light is sized to do the job. I will agree with him if it is an under sized light.

 

What's the city's water source? Algae is often a problem when water is retrieved from a reservoir.

It may be that the type of filter that you have is not filtering out all the microorganisms and algae. Some RO/DI filter manufacturers tout that their filters remove 98% of contaminants in water, but that still leaves 2%.

Changing the clear lines to eliminate light will eliminate the algae growth in the lines. Algae needs light to grow. Is there a way to cover the lines with something to prevent light? Algae is also more apt to grow when phosphates and nitrates are high.

You do not know what is in water until you have it tested. A water test should be helpful to test water for algae. In some areas that have reservoir water, the city sends a monthly water report so consumers can be aware of algae content in water. They are reminded to keep an eye on their filters. Perhaps a water test on water before it enters your filter system and afterwards would be informative. DEQ - Interpretation Of Common Tests

Maintenance generally involves changing the filters (sediment and carbon) every 6 months and the DI once a year. The RO membrane may last 3 to 5 years.

 

Thanks guys, I found some things wrong on my home system and fixed them (biggest problems was a broken water gage that showed 60 PSI with no water!) and got my PPM down to about 20 of TDS. Question for the group - if I put 2 RO filters in series, would that get a much cleaner water out?

 

Micro-organism growth in RO systems is not all that unusual. That is why sanitization procedures are recommended when changing membranes and filters.

Only one RO is certified as a microbiologiacal (virus and bacteria) barrier through NSF and unless you have that particular model, none others are secure against organic growth. In fact, water is so clean that even the most minimal of organic spores, cells, etc. can lead to colonization because it is a such a perfect environment. Many orgqanisn are hetrotrophic.

Simply changing filters will do little to rid the contamination. RO membrane pore sizes are generally small enougth to prohibit organic cells from passing through. However, studies have shown that organism 'living' ON the membrane can somehow permeate it nonetheless and that is why most ROs are not certified as organic barriers.

I agree that DI fiters are not normally recommended for drinking water systems. Mixed-bed, color changing media in 10x2 inch cartridge will last a very long time and I have never seen 'lots of junk' left behind. The point is, an adequate RO is ample for remvoal of TDS. DI filters are most often used in industrial, commercial laboratory work.

There are small Class-B UVs that can go on RO systems and should work fairly well.

Andy Christensen, CWS-III

 

Thanks for the great info, do you happen to know if putting one RO system in front of another, with 2 RO membranes - would the water be even cleaner?

 

I can see that you are a 'thinker' and I like that approach to solving problems...even if there isn't a problem. But let me ask you this: what is the purpose of the product water? Drinking?

ROs in industrial applications can run in a series. (3 into 2, 2 into 1 for example) Usually the concentrate from RO membranes is recycled back into the intake (source) water to conserve water. Additional storage and (pressure) pumping equipment is needed. For residential purposes, though, this is unnecessary outside of personal research or 'hobbying it'.

The answer would be: YES, the water would be 'cleaner'. Micro-organism control a horse of a different color.


Andy Christensen, CWS-II

 

Thanks much, I think the answer for me is to get a quality
DI filter - the kind with beads that change color when they are spent, putting 2 of them after my RO system - to really get the TDS down to a few PPM.

As far as algae - I think it's my water tanks, I've never disinfected them. I'm going to get a whole new system and new tank, and if algae comes back, I'll put a UV filter in front of everything, then replace the tank and flush everything with bleach, etc. thanks much!