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Re: High pH



     >1/4 water change every week with RO water buffered with tap water to 
     >the above hardness. RO water is PH 5 with zero hardness. Tap water is 
     >PH 8.0+ with hardness of 150ppm.
     
     <Details snipped>
     
     >I thought the RO unit would solve this problem but now I am baffled. 
     >How can the PH be so high with the hardness at this level? Any 
     >suggesstions as to how to lower the PH would be most appreciated.
     
     Tap water often has a high pH as a result of the treatment process.  
     For example, Austin tap water is pH 10 with 150 ppm hardness.  
     However, I have found that if you aerate tap water for 36-48 hours, 
     the pH drops to 7.4-7.5.  I keep a 30 gallon plastic trash can filled 
     with tap water and aerated; I draw all my changing water from here.
     
     Have you measured your tank pH at the end of the week, or just 
     immediately after a water change?  I suspect you will find the pH to 
     be much lower at the end of the week.
     
     It's not the hardness that is causing your high pH, and you are 
     accomplishing nothing by adding unbuffered RO water.  Unless you are 
     planning on spawning discus or tetras, there really isn't any 
     compelling reason to keep adding RO water.  150 ppm hardness is OK.
     
     Is there anyone on the list familiar with water treatment procedures 
     who can explain why tap water can have such a high pH?
     
     Kind regards,
     
     Mark