How will we know when to change the activated carbon filter?

1.the most convenient method: look at the pressure difference of the pressure gauge on the side of the tank; (after backwashing)

2.You can use the Residual chlorine reagent to test to product water Chlorine content.

If the water color changed, then need to replace new activated carbon. 

3.Just do a simple small test:

Take a part of the activated carbon in the activated carbon filter tank, and then take a part of the new activated carbon into the water to observe whether there are a lot of small bubbles in the water.

If the used activated carbon produces less bubbles than the new activated carbon, then indicate that the saturation of the used activated carbon is full and needs to be replaced.