Low PH

[Wes]

It is not unusual for there to be a Phosphate reading coming out of an RO/DI array. Apparently it is really hard for them to remove phosphates. I found (on two different units tested) that when the RO/DI first starts making water that the phosphate reading is around .05 and that it drops down to .03 after 15 minutes or so. Because of this, I make large quantities of RO/DI water and use it all before making more. If you make lots of smaller quantities, you end up with higher PO4 readings.

Plus the Hanna low range meter has an accuracy of +/- 0.04. I wouldnt get too hung up on a positive reading from the RO/DI water if you are getting 0 TDS. It could be a matter of your meter being on the high end of the +/- 0.04

Specifications

Range: 0.00ppm - 2.5ppm PO4
Resolution: 0.01ppm
Accuracy: +/- 0.04ppm
Battery Type: 9 Volt (included)
Method of reading: Adaptation of the ascorbic acid method - The reaction between phosphate and the reagent causes a blue tint in the sample.

 

[meschaefer]

Plus the Hanna low range meter has an accuracy of +/- 0.04. I wouldnt get too hung up on a positive reading from the RO/DI water if you are getting 0 TDS. It could be a matter of your meter being on the high end of the +/- 0.04

True, but the significant point is not that there is a finding of phosphates but that there is a change in the level after running the RO/DI system a bit. This has been tested on at least two different meters and with an ELOS test kit. If you search around on the various forums out there, there is a lot of commentary out there. There is also a change in TDS too (First few minutes of water produces .02 on my system, and then quickly drops to 0)

 

[Wes]

True, but the significant point is not that there is a finding of phosphates but that there is a change in the level after running the RO/DI system a bit. This has been tested on at least two different meters and with an ELOS test kit. If you search around on the various forums out there, there is a lot of commentary out there. There is also a change in TDS too (First few minutes of water produces .02 on my system, and then quickly drops to 0)

True but in my opinion that small amount is negligible when proper phosphate export methods are being used. I make water 5g at a time w/out "letting it run" and had a reading of 0.01 in my tank last week.

 

[meschaefer]

True but in my opinion that small amount is negligible when proper phosphate export methods are being used. I make water 5g at a time w/out "letting it run" and had a reading of 0.01 in my tank last week.

Not to bad in that situation, after all it is probably running for about an hour before it is done. But, I had a friend who had set up his RO/DI to automatically fill his ATO (bad on a bunch of levels). The result was that he was forever making very small batches of water, with elevated levels of Phosphate. He then used this water for not only top off, but water changes, and making two part part. It got to the point that it was no longer negligible.

 

[Wes]

Not to bad in that situation, after all it is probably running for about an hour before it is done. But, I had a friend who had set up his RO/DI to automatically fill his ATO (bad on a bunch of levels). The result was that he was forever making very small batches of water, with elevated levels of Phosphate. He then used this water for not only top off, but water changes, and making two part part. It got to the point that it was no longer negligible.

Thats a very good point i never thought about that situation.

 

[jackson6745]

I've had my tank down to 7.7 and never noticed any problems, especially when I ran a reactor. D you guys actually see something negative happening in your tank when your PH dips below 8 ?

 

[meschaefer]

I've had my tank down to 7.7 and never noticed any problems, especially when I ran a reactor. D you guys actually see something negative happening in your tank when your PH dips below 8 ?

My 65 used to run below 8 all the time. No problems.