r/o ph
- Thread starter kennethstowell
- Start date
r/o water should be pretty darn pure H2O so, the pH should be neutral 7.0
Water run thru a reverse osmosis unit should have absolutely nothing that can be detected with our test kits, if you're getting a nitrate reading, either your kit is no good or a cartridge or 2 needs to be replaced in the unit.
Water run thru a reverse osmosis unit should have absolutely nothing that can be detected with our test kits, if you're getting a nitrate reading, either your kit is no good or a cartridge or 2 needs to be replaced in the unit.
A TFC RO membrane will remove 93-96% of nitrates, not 100%.
Grade A pure water is pH 6.5-7.5, but that doesn't matter since you're going to add it too a ton of buffered saltwater (or adding salt to it). If the pH is 2.0 or 10.0 before you add it, it'll be 8.3ish afterwards. Pure water simply has zero buffering ability and will not keep it's pH when you add stuff to it (so don't worry about the pH of your RO makeup water--it simply cannot hurt your tank no matter what the value is).
FYI here's some Total Dissolved Solids (TDS) readings from my RO/DI system:
Tap water: 250ppm
after RO membrane: 10-20ppm
after DI stage: <1 ppm
So there is stuff in RO water. It's not pure. But it's leaps and bounds better than tap.
Ty
Grade A pure water is pH 6.5-7.5, but that doesn't matter since you're going to add it too a ton of buffered saltwater (or adding salt to it). If the pH is 2.0 or 10.0 before you add it, it'll be 8.3ish afterwards. Pure water simply has zero buffering ability and will not keep it's pH when you add stuff to it (so don't worry about the pH of your RO makeup water--it simply cannot hurt your tank no matter what the value is).
FYI here's some Total Dissolved Solids (TDS) readings from my RO/DI system:
Tap water: 250ppm
after RO membrane: 10-20ppm
after DI stage: <1 ppm
So there is stuff in RO water. It's not pure. But it's leaps and bounds better than tap.
Ty
You could simulate the pH impact of R/O water on your tank.
Take one cup of tank water.
Measure pH.
Add 1ml of R/O water to simulate the proportion of make-up water you'll really add to the tank.
Test the pH again.
Needless to say, it won't have changed.
Take one cup of tank water.
Measure pH.
Add 1ml of R/O water to simulate the proportion of make-up water you'll really add to the tank.
Test the pH again.
Needless to say, it won't have changed.
randy holmes-farley
Advanced Reefer
- Location
- Arlington, MA
Several effects are possible here:
1. Any mixing of a lower pH water with a higher pH water will bring down the pH of the higher one, but the change may be very small when one is buffered (tank water) and the other not so much (RO/DI water).
2. Pure water will have a pH of about 7, but it is very difficult to measure with a normal pH meter because there is little buffering and the pH swings around over several pH units. Also, trace impurities on the probe and container will dominate the pH.
3. Pure water will quickly absorb CO2 from the air, lowering the pH. Also, water getting through an RO can have quite a lot of CO2 already in it if the source water has such CO2.
4. pH probes are somewhat sensitive to other things in tank water (like sodium). Thus, if you substantially change the salinity by adding RO water, the pH can "appear" to change, when in reality the actual pH change may not be what you observe. This effect isn't likely to be important with normal salinity changes in a reef tank, but could be if you mixed large amounts of RO water with tank water in a cup.
1. Any mixing of a lower pH water with a higher pH water will bring down the pH of the higher one, but the change may be very small when one is buffered (tank water) and the other not so much (RO/DI water).
2. Pure water will have a pH of about 7, but it is very difficult to measure with a normal pH meter because there is little buffering and the pH swings around over several pH units. Also, trace impurities on the probe and container will dominate the pH.
3. Pure water will quickly absorb CO2 from the air, lowering the pH. Also, water getting through an RO can have quite a lot of CO2 already in it if the source water has such CO2.
4. pH probes are somewhat sensitive to other things in tank water (like sodium). Thus, if you substantially change the salinity by adding RO water, the pH can "appear" to change, when in reality the actual pH change may not be what you observe. This effect isn't likely to be important with normal salinity changes in a reef tank, but could be if you mixed large amounts of RO water with tank water in a cup.
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