Will RO filter lower PH

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jglove276

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Nov 30, 2009
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I am on city water but it has a high Ph around 9 and I am sure it is hard water. My question is will softening the water with a RO filter also reduce PH.
 

dundadundun

;sup' dog? ;woof and a wwwoof!
Jan 21, 2009
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depends on what particulates may be in your water. i doubt it will have a large affect on city water.
 

foolishfish

Registered Fish Offender
Dec 10, 2008
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Where the wild things are
Had a recent bout with a sudden pH increase from my water company rerouting our supply and it was a pain.

I would start by asking your water company for their annual report (good base line but it doesn't reflect seasonal and occasional changes). Test for just what it is that makes your water hard or pH high. I found my carbonate had quadrupled, so I needed an acid buffer to break up the carbonate so I wouldn't get into a pH bounce mode, so say'eth the good folks at Seachem.

What they didn't mention, and I didn't know enough to ask, was that their buffers and Neutral Regulator all have phosphate in them, so then all of my planted tanks started growing algae. Then I had to remove the phosphates, which are buffers to help stabilize the pH. Kind'a maddening. Added some more driftwood and increased water changes so things are back to normal.

If you have an extension service, university or water filtration company nearby you might try getting an analysis from them before you go sockin' the money into an R/O system. If your fish are already pretty well acclimated to mineral rich water you'll end up going through all kinds of fun to put back essential parts of whatever the R/O has removed.
 

jmhart

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Sep 8, 2007
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RO water will pull water closer to 7.0. Therefore, if your source water is higher than 7.0, it will lower it. Conversely, if your source water is lower than 7.0, it will raise it.

So, in your case, RO water will soften and lower your pH. If it has a pH of 9 out of that tap, it's a safe bet that it's VERY hard.
 

Rbishop

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Dec 30, 2005
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Is that tap pH on a sample that set out overnight in a shallow dish? What pH does your tank(s) currently read? In general, if your tap pH is over 7.0, the RO will help lower it. Depending what is in your tank, it may go back up a little.
 

jglove276

AC Members
Nov 30, 2009
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Is that tap pH on a sample that set out overnight in a shallow dish? What pH does your tank(s) currently read? In general, if your tap pH is over 7.0, the RO will help lower it. Depending what is in your tank, it may go back up a little.
My Ph reading of 9 is directly from the tap it was not set out for a period of time. Currently my tank Ph is about 7.5 however that is do to a product my local fish store provided called Water-Rite. This is a declorinator and Ph adjuster. The problem is they are having problems with their supplier and I don’t know when they will have more. This is the reason I am looking into the RO system if that is all I need besides Prime or another declorinator it will be one less product I will have to hunt down.
 
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