What are the Recommended RO filters for a Marine Tank

Discussion in 'Test Kits, Controllers, Reactors and Dosers' started by Nemeziz_za, 23 Jan 2015.

  1. Nemeziz_za

    Nemeziz_za

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    Hi Guys,

    So Im about to replace the pre and post filters and membrane of my RO machine and it got me thinking.

    Do I have the correct RO pre and post membrane filters? So here is my simple question.

    What are the "correct" pre and post membrane filters? (I have a 5 stage RO unit currently)

    Looking forward to your guidance and insight.

    Thanks
     
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  3. Nemos Janitor

    Nemos Janitor

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    The best option IMO is to first check the water quality of the source water.

    The point of the pre filters is to protect the RO membrane. Poor water quality (bore hole water) will require more or bigger sediment filters.

    I like to have two or three sediment filters before the carbon block filter. Then the RO membrane. The good water is then pased through a DI resin.
     
  4. Nemos Janitor

    Nemos Janitor

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    If you have good pre-filters (sediment filters) and change them regularly you RO membrane can last 5-6 years.
     
  5. Nemos Janitor

    Nemos Janitor

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    Just a bit more info on sediment filters. You get them in a few different micron sizes. Most common are 10, 5 and 2 micron. You also get normal and absolute filters.

    The 5 micron filter is the most common one used in aquarium RO units.

    If your RO membrane is not lasting or water production is slow but you have pressure then it might be an idea to start with a 10 micron sediment filter in the first chamber, then a 5 micron in the second. If you want to really extend the life of the membrane then add a 2 micron filter in a third chamber.
     
  6. Nemeziz_za

    Nemeziz_za Thread Starter

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    Thank you, most helpful!

    My source is a municipal tap and it's reasonable to good in quality, I have tested the TDS and it ranges between 84 and 120 but always below 150.

    The longevity of the membrane is amazing. I was going to just replace it with the filters now. Which it would seem I don't need to do.

    For the post membrane filters other then the DI filter is there anything else I should consider? For example taste and odor filters are a waste.

    I'm going to take your advice on the pre filters and run a 5, then a 5 and a 2 micron and see how that runs. These are string filters?
     
  7. Nemos Janitor

    Nemos Janitor

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    The RO membrane might need to be replaced. Check the TDS and flow rate.

    As I said previously, the quality fof the water in "sediment terms" entering the RO membrane and volume determins the longevity.

    As can be expected, if a RO unit is not used often there could be anaerobic bacterial build up within the sediment filters. The reason for flushing. Some newer systems have a UV to combat some of this bacteria.

    No matter what system you have it needs to be used regularly. Else it will clog and water quality will suffer.

    Post treating is manly DI resin. You could also use a GFO or GFH if P04 is present. Or a pH buffer. Be careful when testing RO water with our Aquariusts test kits. They rely on ionic balance and RO water is depleted of irons.
     
    Last edited: 23 Jan 2015
  8. Ridwaan

    Ridwaan

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    Sorry for the hijack but while we on the subject of R.O units...we have a carbon block in our R.O units.
    I assume it contains only carbon. Why is it that we should change it every 6 months but the carbon in our tanks should be changed after 3 to 4 weeks?
    Does the carbon in the R.O machine last longer because it is a differant type of carbon?
     
  9. Nemos Janitor

    Nemos Janitor

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    Good question Ridwaan. :m106:

    Carbon blocks have two properties. Absorption and adsorption. In the case of absorption it is the quickest to "deteriate". This is why sediment filters are used. Adsorption is a chemical form of filtration it filters out heaver irons.

    Let's recap.

    In a aquarium environment there are many "irons" within the aquarium and the carbon adsorption quickly becomes saturated. In other words the chemical process becomes limiting.

    In a aquarium environment the absorption properties are one of a biological nature housing nitrifying bacteria.

    In a RO unit the purpose is different in that the water is partially "cleaned" by the sediment filters. This allows for les adsorption.
     
    Last edited: 23 Jan 2015
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  10. Nemos Janitor

    Nemos Janitor

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    Huh...:m01:

    One has to remember that in an aquarium situation the GAC is filtering 1000lph or more where in a RO situation it is filtering a few hundred liters a day..
     
    Last edited: 23 Jan 2015
  11. Ridwaan

    Ridwaan

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    Thanks so much Kieth...it makes perfect sense.
     
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