Why is my PH 5.4 out of my RO/DI??

[LobsterMobster]

The tap of my ph is about 7.6, but the tds is ~175. Much too high for my liking. As I understand it, my ph should be right near 7 out of my ro/di. Why is mine so low? I know the rule of thumb is to leave your ph as it is, but I keep a lot of different types of fish, a lot of which would prefer neutral water.

I use a Kent Maxxima Hi-S 60GPD unit. 1 micron prefilter->carbon->Hi-S membrane->DI. Ph was measured using a Hanna combo meter and a jungle lab quick dip test strip.

Can I get some help?

Thanks,
KRIS

[angel12]

Stupid question maybe but - have you added essential minerals back into the Water for example Kent RO right or likewise products ... Your water will show such a low reading as it is completly lifeless and has no life sustaining minerals in it .. you need to re constitute your water adding minerals and Kh in order to give you the desired PH you are looking for ....

if you have already done this then ignore this reply

:)

hi all,

Regarding pH of pure R/O:
Here is a link regarding Pure RO / PH readings.
I don't know if he is right. But according to him the pH can't be measueared in pure R/O. he goes on and explains why but hey I am only a hobbyist.

http://www.thekrib.com/Filters/ro.html#00

The tread is from George Slusarczuk, about in the mid section.

Walter from Air/Water and Ice (I think that is right) has also told me that the pH of pure R/O would be neutral 7.

I use right now R/O only which is reconstituted with Joe’s recipe. I get a pH of 6.4-6.5
I don't even bother to test before because I get all kinds of readings.

hth Ronald
Ronald

[RandalB]

Ron,
He's exactly right. You can't read the pH of RO water. RO water is pH 7.0, but will read different pH's depending on the Meter, test method, etc. The slightest contamination of the water by acid or base will also cause the water to shift pH immediately up or down.

Kris, Don't worry about the pH coming out of your RO unit, worry about the conductivity or TDS. As long as it's below 3 PPM TDS don't sweat it. (Yes it should be 0, but meters will not always read TDS that accurately. Temperature effects readings..)

HTH,
RandalB

[LobsterMobster]

Thanks Randal. That's what I suspected. My TDS is ~5 these days. The DI cartridge is pretty well exhausted, but I'm too lazy to change it and the fish don't seem to care (yet). I'll change it before it hits double digits.

Thanks Again,
KRIS

Kris,

I have left the DI completely off now.
It changed the output from 0 to 20 conductance. So the DI did not make such a big difference in my case, but was exhausted after about 250gal R/O water. That became a cost factor.

Ronald