Swimming Pool Conversions

Becoming aware of the concept of natural swimming pools, it seemed to me swimming pool conversions were the next logical step. With some 4 million chlorine pools in the U.S alone, surely some pool owners would appreciate an ecological pool design.


Pool conversions gradually turned into my pet project. I set out to design a way to convert existing pools to natural filtration. Chlorine free with no chemicals of any kind. Maintaining crystal clear, fresh clean water.

It turns out that it may be fairly easy to attain. Well designed pool conversions should, along with natural swimming pools, easily meet municipal ‘drinking’ water standards. This with minimal change to the existing pool.

Adding a conversion may require a bit more elbow grease at first, but truly shouldn’t be much more work than the traditional chemical bath of a chlorine pool. A true chlorine alternative.

The building of pool conversions requires a basin equal to 5-10% of the pool by volume, and about 4ft deep.(1 cubic foot=7.48 gallons) Attached is a smaller basin up on the pool deck. This allows for getting around the pool as well as for excellent oxygenation.


Creating a sort of generic ‘flow form’.


Basins may be constructed of concrete, faux stone, adobe/stucco , stone mortared, or even wood.

Covering the pool with ‘Pebble Tech’ plastering will add to an overall more natural feel. You could even cover the basins.

I do like the idea of lining with a pond liner, otherwise. There will be less chance of mineral leaching in the water, plus a pond liner may go years longer without any maintenance. You never want to disturb a filter basin that is working properly. Cleaning out the filter basins with the up-flow filtration should be a rare occurrence.


Fill the basin with some sort of inert gravel, maybe half inch size, haydite, or clay beads. Haydite is especially good due to its incredible surface area for beneficial bacteria to adhere to. Bacteria that is required for biological filtration.

Some water gardeners cringe at the idea of using cinders due to what they’ve seen as a clogging problems. This may be because of large fish loads that the filter simply cannot keep up with, but cinders may also add minerals that you don’t want. So ultimately I can’t recommend using them.

Use a Jandy valve to divert 2/3rds of the water away from the existing plumbing to percolate up through the larger basin. From there the water pours out and down into the second smaller basin, and finally back to the pool.

Within the pool conversions larger basin grow a diversity of aquatic plants. Good choices are aquatic mint, for its antibacterial properties, and reeds. It is of course best to have plenty of diversity. Diversity being the strength of any ecosystem. All combined, the system will complete the nutrient cycle.

When deciding on placement of the filter be aware of the skimmer, a very important piece of the filtering process. Everything floats first and should be removed before they can break down. Good circulation within the pool is essential.

UV Sterilizers could be used for further polishing of the water. This depends on personal preference and tolerances.

Bacteria Culture or Microbe Lift may be used in the filter basin to ‘seed’ the bio-filter, adding diversity and to speed up the bio-filtering process.

There you have it; a naturally filtered swimming pool, with a two-tiered pool waterfall and beautiful water garden to boot. Pool into pond conversions offer a true chlorine alternative.No more chlorine poisoning, chlorine allergy, chlorine irritations or cancer risk. Pure chlorine free pool swimming.


*Scientific American – Chlorinated water exposure may boost cancer risk.

I would like to add, that after discussions with Dr. John Todd of Ocean Arks International and Michael Littlewood of Eco Design Scape and author of “Natural Swimming Pools”, I have added faith and professional support in the design.

If planning any ecological pool conversions of your own, PLEASE let me know and keep me posted as to your progress.



David W. Crimmins Permaculture Design

Available for Consultations in Arizona

For more about converting existing pools See:

* Gartenart.com
* NaturalSwimmingPools.com pool conversions

* Wet-Web Media Pool Conversions

* Erik’s Swimming Pool to Pond Conversion

“Natural Swimming Pools: Inspiration For Harmony With Nature” by Michael Littlewood.


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