PH bounce, what exactly does this mean? Should I expect to see some kind of rebound or is this another pool phrase.
I am talking specifically about vinyl liner pools and the need for the alkalinity buffer to create a stable pH. We are used to adding bicarbonate of soda to the water to create a buffer at levels of 80-200ppm but bicarbonate of soda actually buffers at pH8.1+, too high for pool use really so we have to add acid to maintain the pH at the correct level and generally the pH climbs (drifts) slightly through splashing or aeration or remnants of sodium hydroxide in the chlorine dosing liquid.
As I am talking about vinyl pools not concrete/plaster/tiled to prevent/lessen the drift upwards in pH I have been lowering the alkalinity steadily over the last few years and currently my pool is at 38ppm alkalinity and I have customers who also have vinyl pools running at 45ppm and 22ppm without any issues and I am still waiting to hear the pH has either climbed through to roof or dropped off the edge and heading downwards. The thing is for each addition of chlorine we can reasonably predict the pH rise and for any acid addition the fall. At no point does this create a chain reaction where hydrogen ions are lost or formed causing a catastrophic “bounce”. What it has meant is barely any acid has been used to correct the pH and there has been no need for soda ash to raise the pH it just stays reasonably stable and why not have the pH move easily without dragging the buffer solution down, so where is the bounce?
I realise that cyanuric acid stabiliser (CYA) is also a pH buffer to prevent the pH from rising but in my own pool I have been experimenting without CYA as well and the dosing system is more than capable of keeping the pH adjusted with very minor amounts of acid, if any at all.
I am trying to minimise chemical usage but also as bicarbonate of soda is carbon and oxygen which is required for almost all life/growth of bacteria etc so restricting unnecessary extra food supplies is where I am heading. I wouldn’t use CYA either as that is also food for bacteria by virtue of it’s nitrogen source. Obviously the use of CYA is currently needed to protect the chlorine from photo degradation but as we know some bacteria can use this and leave ammonia behind for us to deal with, there does seem to be a possible link to CYA and strains of E coli.
oligotrophic (low nutrient) water tends to have lower alkalinity while eutrophic (high nutrient) water tends to have higher alkalinity. So I am trying to work with the low nutrient water, it’s not a pond, it’s a pool and if I could just have H2O. I have been trying to throw my pool water out of the prescribed ranges waiting for bad things to happen but they don’t I just have perfect clear bacteria free 0.5-1 NTU water.
What are others thought on alkalinity in vinyl pools and pool chemistry?