RO Filter not doing what it supposed to Important

Discussion in 'Reverse Osmosis Filter for Freshwater' started by virusmk, Jul 1, 2014.

  1. virusmk

    virusmkWell Known MemberMember

    Firstly need to apologize to moderators as i could not find section for RO filters

    Not long ago i did install RO filters on my tap water (sediment (papaer) filter one canister and mineral/chemical filter) second canister.

    Now as it was suggested to me that this RO unit will signigicantly drop water ph i went and got it.

    As a big surprise to me now after 3 montchs ph diference between tap water and RO water is just .2
    Tap ph 7.6 RO 7.4

    What is going on here? What can be done to make this ro unit to work properly?
  2. Claire Bear

    Claire BearWell Known MemberMember

    Hi, not sure but my ro/di water is significantly lower. Tap is 8.3 and RO is 7.6
    Is it possible the RO system is not properly installed? I just can't imagine it not lowering the ph!
  3. Dolfan

    DolfanFishlore VIPMember

    It sounds to me like you just have a regular type water filter and not a true Reverse Osmosis filter. RO filter have a filter membrane that is somewhat costly to replace and needs to be done every few months depending on your original water quality and how much you use. So maybe you just need to replace the RO membrane if it is a true RO filter.

  4. Thai Aquarium ownerWell Known MemberMember

    +1 Dolfan post
    A true RO unit with the correct membranes and filters that are installed correctly, should reduce the Ph level to around 6.2 / 6.4

  5. _Fried_Bettas_

    _Fried_Bettas_Well Known MemberMember

    Curious variance here, my RO filter gives me water that is nearly perfectly neutral. 6.8 to 7.0 with a TDS of about 10 ppm. My tap water is 8.0-8.2 with TDS over 1000. I figure my filter needs replacement when my TDS gets over 30 and the pH drifts above 7.2.

    Whatever the case, it does sound like replacement membrane is needed.
  6. junebug

    junebugFishlore LegendMember

    RO is supposed to come out a perfect 7.0... as should DI water. I can only suggest you read over the instructions and if necessary, change out the assorted filter media.
  7. OP

    virusmkWell Known MemberMember

    I got it as Ro Filter for everyday drinking water. Once i go home i will take photo of it and buy look some of you might recognize what has been sold to me.

    I have tested for KH and GH and it gives me somewhere from 50 to 80ppm

    Is there separate test for total disolved solids or standard kh gh test kit?

    I will have a look and if needed i will change filter media to something thats going to offer better filtration
  8. _Fried_Bettas_

    _Fried_Bettas_Well Known MemberMember

    There are RO filters that only partially filter the water, supposedly for drinking water like you say. I know nothing about them myself or what is "partially" not filtered out.

    Most of these filters are modular and more than likely the RO membrane that is with that one could be replaced by a standard 50 gph membrane for more total filtration.

    They sell inexpensive TDS meters on Amazon/eBay here and presumably at whatever similar outlets are available in Australia.
  9. matsungit

    matsungitWell Known MemberMember

    RO water pH can be wacky since it has little to no KH. Reducing dKH means reducing pH as well. Less than 3 dKH can result in very unstable pH. See if you are effectively reducing dKH first. Only then can you see the pH go down.
  10. OP

    virusmkWell Known MemberMember

    Its going to be almost imposible to reduce carbonate hardness to less than 3 as i do have quite hardish water, even though i need to achive it, its better for my discuses.

    This is the unit that i have at the moment. I did not got if from him but just as ilustration i have almost identical to it.

    I did replace sediment (old was 25 microns) new one is 2 microns and chemical/mineral (old 1 micron0 new 0.2 microns as i tought as smalller the gaps in filter catriges are better filtration i will get but no changes at all.

    Only top little filter i cant replace as i do not know how to remove original and replace it with something better.
    Any suggestions would be welcomed.
  11. _Fried_Bettas_

    _Fried_Bettas_Well Known MemberMember

    The prime function of sediment filters in an RO system are to extend the lifetime of the RO membrane as it gets fouled up and damaged by having to filter out the larger stuff.

    A RO system functioning properly should be able to produce nearly pure water regardless of the hardness of the source water. The membrane will just last a shorter time with harder water. I have extremely hard water and still end up with low TDS and 0 dKH and 0 dGH. My hardness is mostly gH though and my kH is comparatively low. Last time I checked I had 40 dGh but only about 15 dKH from the tap.

    Note that I remineralize my water with SeaChem Equilibrium to around 2-3 gH and use SeaChem Alkaline to buffer the water with 1 dKH so that CO2 doesn't crash my pH.
  12. OP

    virusmkWell Known MemberMember

    _Fried_Bettas_ i will try to replace my filter membrane with new one with slower waterflow in hope that would reduce mineral content in the final output.

    do you have live plants?

    Plants would benefit from having exes co2 and would prevent having ph spikes.

    I do use alcaline buffer and discus buffe combined togeter as i have been advised by seachem to use them together to prevent any instability
  13. _Fried_Bettas_

    _Fried_Bettas_Well Known MemberMember

    I have live plants in all my tanks. I don't know much about discus buffer, but I do use alkaline buffer with acid buffer in one apisto tank to keep the pH around 4.5. Otherwise I just use very small amount of alkaline buffer which appears to be enough to keep the pH form being unstable. It appears to take very little, like I say about 1 dKH regardless if it is a compressed CO2 system or DIY CO2.
  14. OP

    virusmkWell Known MemberMember

    At the moment i only use seachem exel as i am not ready to install co2 system yet so i dont know much about its side effects to the ph.

    I did managed to remove the Ro membrane, it is .5g in minute waterflow and i am looking around to find one suitable for my system. Now if i do get 2 of them and put them one after eachother , would that give me better filtration ?
  15. matsungit

    matsungitWell Known MemberMember

    It's not so simple as putting them in series. The membranes have to match and the flow restrictor has to match as well.


    Remember: Both membranes have to match. You only need 1 flow restrictor and it has to match the one membrane rating, not combined. For example two 75gpd membranes equals one 75gpd flow restrictor.
    Last edited: Jul 3, 2014
  16. OP

    virusmkWell Known MemberMember

    It should not be too hard to figure it out. Now i just need to find RO cartridge with membrane inside that would be suitable to the unit that i have.

    I have cut the old ro filter and on surprise there is no membra e inside, instead there are some fine minerals for purification.
  17. OP

    virusmkWell Known MemberMember

    Ok i finaly found 50gpd membrane tnat sims to be suitable, did order it so now hopefully would fit in. If it does what it supposed to ill be ordering one more and will conect them one after otherone

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