The filtration zone on my natural pool comprises of perforated pipe on the bottom and covered with 3 ton of 13mm gravel from Southwest Riverstone.
The water flows through the gravel and plants into a pressure filter with zeolite then back to the pool continuously filtering it perfectly keeping the water crystal clear.

The black Oase skimmer runs through a pressure filter also circulating the water and stopping leaves from sinking to the bottom but if any leaves do escape the skimmer the natural pools robot scouts the bottom of the pool keeping it clean.

A side scrub twice weekly keeps the sides of the pool clean and looking great.
With this set up and running for the past 6 months the Ph and all other variables measured are below good running variables which is what we want and Ph does not change from 6.8-7.2.

Now being winter the plants have died back and are dormant but will soon grow like crazy.

The water temperature is 14 degrees at the moment with a high in peak summer of 28 degrees.

The water is topped up from our rainwater harvesting of which we have 3300 liters and only takes 47mm of rain to fill tanks. So they should never get empty.