02-08-2018, 09:15 AM
Join Date: Apr 2005
Location: Brentwood, CA, USA
iTrader Positive Rating: 100%
| | Re: RO/DI Filtration and 8.0 Ph?
I have been thinking about this subject for a few days, based on another thread here: We are very used to having our water behave in certain ways, including maintaining a reasonable pH even if we do nothing to make it do so. We also constantly hear that we need to keep our KH above some value or we will get a pH crash, because the KH is a buffer - this is incorrect but I think it is a clue. Normal water always has a KH above zero, meaning there is always some amount of carbonates in the water, and atmospheric CO2 keeps the amount of carbonic acid in the water above zero. So, the carbonic acid/carbonate buffer is always there, trying to keep our pH relatively stable.
You ran your water through a RO/DI filter, you might have removed all of the carbonate ions from the water, leaving it without a pH buffer. So, suppose you somehow have an alkaline compound in your water, perhaps from fertilizing or from another substance you added to the water. Without the carbonic acid/carbonate buffering the added alkaline substance caused the pH to go up an abnormal amount. I would have expected to see the pH drop due to the unbuffered carbonic acid from atmospheric CO2, but if the amount of added alkalinity was greater than the acidity from carbonic acid, the pH would go up.
That is just a germ of an idea right now.