[BBRC2]

I've been having problems keeping ph up where I would really like it. I have a 5 stage brs rodi unit with auto shut off on a brute can. I had a airstone in the can always running until today. I pump over rodi to my other brute can and mix salinity salt then let it mix for 24hrs. Then I heat it to temp and make sure I am at 35ppm. Then I pump it out into 4 sealed buckets. When I checked it right after mixing it was about 7.9ph. My tank ranges for 7.9 during the day and drops to 7.8 at night. I auto top off with kalk. I have used numerous test kits and brand new ph probs. alk and calcium are perfect everytime I check.

Should rodi be buffered before mixing salt in?

Aquavitro told me today that I should not have the airstone in my rodi water as it will push out the co2 and I should mix and use it in less than 24hrs. That just don't sound right to me. Being winter I would think less co2 would be a benefit in a closed up house.

Any advice to try.

 

[cmaxwell39]

Dissolved CO2 will form an acid in water (carbonic acid) and drive the pH down, so their reasoning in not running air stones seems flawed to me. I am not sure whether or not you need to run an airstone in the storage bin or not, but their reasoning seems flawed.

As far as a pH of 7.9, I would not worry about it too much. The more important thing is that it is steady and does not flucuate too much. The fact that the pH is a little lower may be to increased CO2 levels in the house during the winter (not as many doors and windows open, we exhale CO2.) Try taking a cup of water from your tank and placing it outside for a half hour and then checking the pH and see if it moves up at all.

 

[on the spot]

Aquavitro told me today that I should not have the airstone in my rodi water as it will push out the co2 and I should mix and use it in less than 24hrs. That just don't sound right to me. Being winter I would think less co2 would be a benefit in a closed up house.

Any advice to try.

This is in a basement, all the moving water around?

whether in a basement or not I'd bet you are bubbling elevated CO2 through the airstone. Switch it out for a powerhead to see what you get. What is the PH of a fresh mix?

What's the PH of the RO water?

 

[BBRC2]

Yes all my brute containers are in the basement. I was bubbling the rodi container 24hrs a day. My fresh batch last night was about 7.9 I have since taken out the airstone. When I tested the rodi water it was just below 7 as far as I could tell. But I've heard there's not a accurate test for rodi water because it's been stripped so much.

 

[iyachtuxivm]

This is correct. When you mix anything with rodi the ph can change greatly. Is your ph that level in the warmer months? As someone else stated if its stable and not below 7.8 I would just leave it be. Its better stable then the perfect 8.3 for a day or two.

 

[BBRC2]

This will be the first summer which were anxious to see if it goes up. At the moment it's 7.84 and should stay there through the rest of the night.

Thanks for the help and advice everyone.