Biofilm on my RO elements

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ITV

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I have a 4 stage RO system which utilizes a 5 micron sediment filter, 5 micron carbon block, 1 micron carbon block and dual RO membranes (in series). The RO system is in daily use since both refriderators are connected to it. I have Lake Michigan city water and my output of my RO system is 4 TDS. The sediment filter is changed every 6 months, carbon filters at 2 years with the original RO membranes (2 1/2 years).

I noticed that recently that my auto shutoff valve was not working correctly and upon taking it apart I noticed that there was a slimy film on the diaphram. After cleaning it, the auto shutoff was working properly.

A call to the RO system manufacture (Bulk Reef Supply), they suggested replacing the RO membranes due to a biofilm build up. There is no off taste or smell to my water.

Can this biofilm build up end up in my beer? Anyone with a similar experience?
 

mabrungard

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No, biofilm or its components can't injure your beer or you when you drink it. If you're concerned with a biofilm, you can soak the membrane unit in metabisulfite solution to kill the biofilm.

Your sediment filter change frequency is way too conservative. If you're on a typical municipal water supply, you shouldn't need to replace that filter for MANY years. If you're concerned with the sediment filter clogging, put pressure gauges upstream and downstream of the filter and replace that filter when you see more than about 5 psi headloss via the gauges. Sediment filters filter BETTER as they trap sediment. It's only when it can't deliver the flow, that you should replace it.
 
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ITV

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No, biofilm or its components can't injure your beer or you when you drink it. If you're concerned with a biofilm, you can soak the membrane unit in metabisulfite solution to kill the biofilm.

Your sediment filter change frequency is way too conservative. If you're on a typical municipal water supply, you shouldn't need to replace that filter for MANY years. If you're concerned with the sediment filter clogging, put pressure gauges upstream and downstream of the filter and replace that filter when you see more than about 5 psi headloss via the gauges. Sediment filters filter BETTER as they trap sediment. It's only when it can't deliver the flow, that you should replace it.
Thanks for your feedback which is great news for my beer.

Regarding the sediment filter, I have a pressure gauge downstream of the filters. I was replacing my sediment filter based on a visual inspection (dark orange in color throughout the filter). Being that they cost $4 each I was replacing it before the discharge pressure was reduced. When the village flushes the fire hydrants (once per year) the initial water comes out rust colored. I should extend the change interval because I knew that they perform better when "aged" but the maintenance mechanic part of me has a hard time with that.
 

mabrungard

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Yep, in your case where you have a known sediment prevalence, a change out is warranted. But I'd still base that replacement on excessive pressure loss.
 

scrap iron

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I am not a water authority but have a basic knowledge of water and ph. I have a 4 stage RO system with one standard type membrane. The system is only used for my brewing and a cup of tea once and a while so not used a lot. I had heard about biofilm and now do the following yearly. One a year I remove all the filters including the membrane. I then put sanitizer in where the sediment filter goes and run it through the whole system until water starts coming out like normal. At that point I let it sit for 30 minutes then flush the system several times to get rid of all sanitizer. Then replace the filters with new ones. I keep track of the membrane with a TDS meter. Here is a writeup on the subject.
How to Clean & Sanitize a Reverse Osmosis System - The Water Geeks
 
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ITV

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Thanks for the reply's. I do the bleach sanitizing once/year. I recently soaked the RO membranes in a metasulfite solution, so far so good.
 
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I have a 4 stage RO system which utilizes a 5 micron sediment filter, 5 micron carbon block, 1 micron carbon block and dual RO membranes (in series). The RO system is in daily use since both refriderators are connected to it. I have Lake Michigan city water and my output of my RO system is 4 TDS. The sediment filter is changed every 6 months, carbon filters at 2 years with the original RO membranes (2 1/2 years).

I noticed that recently that my auto shutoff valve was not working correctly and upon taking it apart I noticed that there was a slimy film on the diaphram. After cleaning it, the auto shutoff was working properly.

A call to the RO system manufacture (Bulk Reef Supply), they suggested replacing the RO membranes due to a biofilm build up. There is no off taste or smell to my water.

Can this biofilm build up end up in my beer? Anyone with a similar experience?
So you actually have a 5 stage system: 3 prefilters and two membranes.

Yes - the bacteria can be a human health concern, and you should treat your entire system. You can find instructions here: https://www.buckeyehydro.com/content/Sanitizing_RO_RODI.pdf

Remember this regarding the frequency of filter change outs: There are two issues here - 1) the functioning of the filter, and 2) the potential for algae and biofilm development over time.

Other comments: Because of the pore sizes of your prefilters, you are using your second carbon block as a sediment filter - it is trapping sediment between 5 and 1 micron. The pore size on any carbon block downstream of the sediment should be about the same, or larger than the pore size on the sediment. So if you want to stick with a 5 micron sediment, use two 5 micron carbon blocks. The sediment being trapped in your second carbon block is trapped there in disinfectant-free water. No good.

Once you have the pore sizes of your prefilters straightened out, place the carbon block with the highest chlorine capacity before other blocks. The concept of successive filters having smaller pore sizes is good, but it applies only to sediment filters.

Regardless of what your vendor tells you, if you want to maximize the life of your RO membranes, run them in series ONLY if you have soft or softened water. We often run membranes in series on commercial RO systems (which is presumably where your vendor got the idea), but commercial RO systems always require soft or softened water. Running membranes in series without soft water is a good way to make you buy new membranes more often.
Hardness.png


Russ
 
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