Calibration Solution for Pool PH Sensor

[turfy77]

Ive got an Astral Pool Equilibrium system with an PH probe and acid dosing system. Astral Pool sell a blue PH solution (PH of 7.5) in a 200ml bottle and needs to be replaced every 12months, it costs $40. I find this ridiculously expensive considering it only last 12months. Does anybody know if there is a cheaper solution you can use. I tried distilled water but am getting a very high PH reading of 7.9 where I would of thought it would be 7.0.

Any advice appreciated.

 

[Patrick_B]

Welcome to TFP,

Some buffers are very expensive but I think you may find them online for less. Here people buy them from various suppliers pretty cheap, but I don't know how good they are, or how well they last. I know buffers that we use in industry are very pricy, much like what you describe, but they are very reliable. Over here, 7.0 is always yellow as a standard and blue is 10.0, but it's obvisouly different with that company, or just down under. Whatever you choose, you need to calibrate with a good buffer to ensure proper readings and pH control. You don't need 200ml so try to find one smaller, and be frugal with its use.

 

[AusJohn]

I appreciate that this is an old thread, but from a lab procurement perspective, $40 for 200mL with a 12 month shelf life isn't hideously expensive. We buy in larger quantities for our lab and pay about $15-20/L for pH buffers, buying a carton of 12 1 litre boxes to get a saving would be a false economy as you just wouldn't get through it. You also have to be a little careful as I see a lot of pH buffers with 3 month shelf life once the bottle is opened. Most pools probably don't need the complexity of a pH probe, but if you're going to have one then it's worth looking after it well and keeping it properly calibrated. Don't use Jiff to clean it either no matter what the manual says. Just soak it in detergent, rinse it with clean water and if you really have to dry it off, just blot it with tissue, don't even wipe it. The glass is very delicate and any surface scratches will interfere with accuracy and reduce the life of the probe. New probes are typically around a hundred and fifty bucks for this type of application so you want them to last as long as possible.

The main consideration with these materials is that you need to keep them sealed well, don't leave them with the lid off. Don't return used buffer to the bottle and store them in a cool dark place. Don't tip them in the pool either, they're usually phosphate based.