Re: when i test ph pool -it reads 7.4 thenif i let it sit it
Pool water is highly carbonated (lots of CO2). In the pool it is difficult for the CO2 to outgas, as there is comparatively very little surface compared to the volume of water. In a small container the surface to volume ratio is far higher and it will outgas rapidly. There are also other reactions that will change the PH, such as the breakdown of chlorine, which will progress far more quickly in a small container than it does in your pool. Essentially, the small container drifts rapidly while the pool is comparatively stable. If you want to know what is happening in the pool, you need to do the test reasonably promptly.