Where in RO unit does phosphate get removed?

10524 Views 10 Replies 7 Participants Last post by lewisrassel, 8 d ago

firsttime

Discussion Starter · Apr 29, 2009

Hello Fellow Reefers,

This has bothered me for a while now and I want all help you can give me to understand it.
"
A decent RO unit has a 4 stages. I would like to know in which stage does the phosphate get removed?"

I have a barebone RO and I put in a new membrane and I am still recording 0.5 PPM phosphate in fresh RO water. So I am guessing that the phosphate removal does not happen in the membrane.

Let me know your thoughts. I am also intending on buying a RO unit ( budget 150 dollars). Please advise which RO unit would be a good one for the money also considering the fact that it should be easy to get replacement parts.

Looking for your inputs.

Thanks

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JB63

· #2 · Apr 29, 2009

My understanding is that phosphate exists in the forms of ions (electrically charged radicals) and the chemical molecule is too small to be caught by any mechanical filtration (such as RO membrane). So, the way PO4 is removed is by binding to some replaceable media in your system, one such is a DI (De-Ionization) canister.

My RO has only 3 stages (Mesh/Carbon/RO) and I'm contemplating adding a DI stage.

All hardcore chemists out there, feel free to 'correct' my explanation.

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Planecrazy

· #3 · Apr 30, 2009

My only correction would be that DI is the only way, not one way. Check out bulk reef supply or buckeye field supply for add on DI kits. Very simple install and fairly inexpensive.

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firsttime

Discussion Starter · #4 · Apr 30, 2009

seems like I might have to go that route. Thanks for the inputs..

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firsttime

Discussion Starter · #5 · May 15, 2009

Reefers, Thanks for the valuable inputs. You were correct the phosphates are removed in the DI , I bought a DI from bluk reef supply ( BTW they are awesome in their prompt service and shipping) tested the first RO water today and its reading zero. I will test it after I add the salt to make sure everything is ok.

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Buckeye Hydro

· #6 · May 17, 2009

It is removed by the RO membrane and the DI resin.

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firsttime

Discussion Starter · #7 · May 25, 2009

After you said that it got me thinking so I did some more tests. The results are as follows

Tap water - 1.5PPM phosphates

Water out of RO unit only - 0.5PPM Phosphates

Water out of RO/DI unit - 0 PPM Phosphates

so you are correct - Phosphates are romoved both in the RO membrane and DI. I am glad you posted your opinion.

Thanks

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JB63

· #8 · May 26, 2009

firsttime said:
After you said that it got me thinking so I did some more tests. The results are as follows

Tap water - 1.5PPM phosphates

Water out of RO unit only - 0.5PPM Phosphates

Water out of RO/DI unit - 0 PPM Phosphates

so you are correct - Phosphates are romoved both in the RO membrane and DI. I am glad you posted your opinion.

Thanks

Rather interesting result. My understanding of PO4 is that it is too small to be removed by mechanical filtration ... but .. I'm open to new ideas.

So, here is one additional test that may help answer this puzzle:

1. You tested water BEFORE RO (1.5 PPM)
2. Then AFTER RO (0.5 PPM)
3. How about water from the waste line of the RO. If RO removes PO4, then this reading should be higher than 1.5 PPM.

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mf2055

· #9 · May 26, 2009

the GFO add on after the DI canister..... :3195:

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Lizzievon

· #10 · Mar 5, 2021

Planecrazy said:
My only correction would be that DI is the only way, not one way. Check out bulk reef supply or buckeye field supply for add on DI kits. Very simple install and fairly inexpensive.

I purchased a 5 stage RO DI system 2 months ago, and am testing .2 phosphates in the filtered water. Geez, now what I thought DI was to remove all phosphates..if I add on a GFO will that solve the problem? But now I am concerned that the filter system may be flawed.

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lewisrassel

· #11 · 8 d ago (Edited)

the way PO4 is removed is by binding to some replaceable media in your system, one such is a DI (De-Ionization) canister.

Nox Vidmate VLC

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