A Water Dialogue With Ng Kok Hong: What We Need To Know About Bio-filtration System

Devisanthi Tunas from Green Asia Force (GAF) talked with Ng Kok Hong (NKH), a waterscape ecologist and a bio-filtration system specialist from AyerMatahari Sdn Bhd (Malaysia).

GAF: You have designed many man-made lakes, bio-swimming pools and garden ponds projects in Asia especially in Malaysia, India and Indonesia that boast a sophisticated and effective bio-filtration system. Could you tell us what is exactly a bio-filtration system and why is it important?

NKH: Water quality management either in small garden ponds to large recreational lake can be complicated. As most owners of water bodies have very little knowledge on water chemistry management, therefore, the chances are high that the quality of water to become deteriorated in a short span of time. To make all things easy for owners, designers and architects alike chose to apply the chlorinated water system like those that applied in swimming pools to achieve a crisp clear water in their ponds either for swimming or not. Unfortunately, such applications of chemicals like chlorine today is not all that favourable as it has been proven to be associated to unhealthy or harmful diseases and not entirely recommended for homes or in public environment.

There is another system commonly used in fish ponds especially for koi fishes. This system is basically a physical filtration system which re-cycle the water over multi-layered chamber packed with gravels or coral chippings, nettings and sponges to filter off solid or physical wastes to achieve a clearer looking water in garden ponds. This physical filter system is expensive and requires a lot of routine cleaning and maintenance. But it is not able to filter away non-physical organic wastes that already dissolved in water.

The water filtration system that is right to dissociate dissolved compounds in water and keep it healthy is the bio-filtration system. It does not requires any application of chemicals and it also function like a physical filters.

A bio-filtration system is a water circulatory system, that involves the activities of the naturally occurring bacteria, designed to breakdown nitrogen-based wastes in water as part of the Nitrogen-cycle process. For such as it is a part of the natural nutrient cycle processes, therefore, the design of the biological filtration system is to maximise the nutrient cycle breakdown to the maximum efficiency. The bio-filtration system can be designed and created with a mixture of local materials that are able to shelter natural occurring bacteria effectively like zeolite or lava stones, dolomite chips and asphalt.

With the application of the bio-filtration system in garden ponds, the water quality can be made crisp clear and clean without any installation of physical chambers and neither involves any application of toxic chemicals like chlorine. This bio-filtration system requires only minimal maintenance other than running the circulatory pumps throughout the period as required.

Water quality tends to deteriorate from accumulation of compounds or nutrients that dissolved in water. These compounds that dissolved in water cannot be removed from physical filtration chamber and neither can they be removed with the application of chemicals like chlorine. The one and only system to remove this compounds like ammonia, nitrates is the natural process of the bio-filtration system in water.

Therefore, the application of the right water filtration system is important as to prevent the pond water quality to be become deteriorated that can rendered any garden ponds as unhealthy. Most importantly is to do away the application of chlorine, a toxic chemical along with its by-products like trihalomethanes that can be detrimental to health.

A bio-filtered pond at St. Regis Resort & Spa, Bali (image credit: Ng Kok Hong)

A bio-filtered pond at St. Regis Resort & Spa, Bali (image credit: Ng Kok Hong)

A bio-filtered pond at The Glades, Kuala Lumpur (image credit: Ng Kok Hong)

A bio-filtered pond at The Glades, Kuala Lumpur (image credit: Ng Kok Hong)

GAF: With the raise of sustainability awareness, there is an increased curiosity toward bio-swimming pool system. What is the most fundamental difference between bio-filtered pools and the chlorine-treated pools?

NKH: Obviously, the attention on the bio-swimming pool is to avoid swimmers too much exposures to chlorine and its by-products. Of late, it is a common fact now that chlorine and its by-products either in swimming pools or in drinking water suggest a positive association between such exposure to these chemicals to increased risk of some cancers in human.

The bio-swimming pool as a water body can be a place to create public awareness about water management and care as part of daily life-style and social culture. It induces the private swimmers to take concern of the bio-pool as it is now has no direct application of chlorine to ‘clean-up’ the system but instead attention and understanding are required from the swimmers.

GAF: Can we build such pool in the tropical context? Should we be worried about unwanted bacteria?

NKH: It is possible to have such non-chlorinated pools in tropical regions as well as in other climates. It is more of a care and understanding of its application and therefore,  education and routine hygienic culture of bio-pool swimmers must be put into practice like those Japanese bathers who religiously cleanse themselves before immersion into a public bath pools.

In natural waters, bacteria and other pathogens are usually not harmful to human. What that can eventually be harmful in a non-chlorinated pools are those bacteria that came from wastes of human and other mammals. Fecal coliform (bacteria associated with human or mammal wastes) like Escherichia coli is one that should concern most in water with no chlorination. Fecal contamination can arise from sources such as combined sewer overflows, leaking septic tanks, sewer malfunctions, contaminated storm drains, animal feedlots, and other sources. These are the primary source of concern of the presence of E. coli that usually indicates the presence of other disease-causing bacteria that can cause diseases like gastroenteritis, ear infections, typhoid, dysentery, hepatitis A, and cholera.

Fortunately, the bio-pools are not associated with fecal contamination sources from sewer, sewage, septic tanks or drains. But this does not mean that the bio-pool are free from fecal contaminations. As fecal coliform live in the digestive tracks of warm-blooded animals, including human, and are excreted in the faeces, therefore, caution must be taken seriously from the swimmers themselves. Swimmers are best to follow strict rules of self-cleaning and practice good hygiene before entering the bio-pool. Pets and free roaming mammals are best to be kept away from the bio-pool.

GAF: What are the things that we need to take care when we decide to build a bio-swimming pool?

NKH: First and foremost what that is needed to build a bio-pool without the application of chlorine is education. The bio-pool owner and swimmers must not expect the bio-pool to be an exact identical in outlook like those of chlorinated pool. A bio-pool is an ecosystem and in contrast to a chlorinated pool, it is a chemicalised body of water. The owners and swimmers must always be aware that exposure to harmful pathogen is still a risk no matter how strict the control applied to swimmers. Additional costs must be budgeted for water quality analysis and fecal coliform tests as part of the routine must be accepted.

GAF: Will heavy rain fall affect bio-filtration system? Can it self-regulate quickly after heavy down pour?

NHK: Like any natural pond, the water quality does react to rain water. If the location of the pool is not at heavy industrial areas with much air and surface pollutions, therefore, there will not be any negative changes to the pool and its water quality. With the running of the bio-filtration system, the water quality is expected to maintain in its optimum form good for swimming. 

GAF: We have seen many images of bio-swimming pools around the world that look unkempt rimmed with aquatic plants with fishes and tadpoles swimming freely around it. While it can be enchanting for some, it can be a deterrent for others. Can bio-swimming pools look like a regular pool?

NKH: The wrong perception of the bio-pool is that it must come along with massive aquatic plants planting as part of the water filtering process. Such planting in the bio-pools along with soil embedded in containers also brings along other kind of unwanted pathogens that live in host animals like snails and worms. We do not recommend uncontrollable aquatic plants planting in bio-pool as they do not serve effective purpose in water cleansing. We preferred the effectiveness of the bio-filtration system as part of the ecological system to maintain a healthy and clean water pool. As the bio-pool is an ecological body, design should be made more in harmony with nature instead of being an engineered and rigid Olympic-like pools. Crisp and crystal clear water like those in chlorinated pool is not the priority but clean, clear and healthy water is what ought to achieve. Creativity with design should be an acceptable culture in the bio-pool design practices.

A bio-pool design for WildWoodsSpa, India. Plants are contained and isolated from the pool water. Water jets sculptures for play and to maintain a high dissolved oxygen level. (image credit: Ng Kok Hong)

A bio-pool design for WildWoodsSpa, India. Plants are contained and isolated from the pool water. Water jets sculptures for play and to maintain a high dissolved oxygen level. (image credit: Ng Kok Hong)

GAF: Do we need to have a significantly higher budget to be able to build such pools in comparison with regular pools?

NKH: The costs for a bio-pool are very much depends on the design as to how the characters of the bio-pool should match its environment. But for basic eco-technological needs on the filtration systems and education, the budget is expected to be higher than a regular pool but not significantly over the board. The electrical power consumption from running the pumps could be higher than regular pools as this pumping or circulatory system is now supporting the living pool cycles and maintaining natural fishes and beneficial bacteria as part of the bio-pool ecosystem.

GAF. Are having fishes a must in the bio-pool ecosystem? If yes, does that mean that there will be fishes in the pool? Or will the fishes be contained?

NKH: Yes, we do need to have fishes as the bio-pool is a small ecosystem by itself, therefore fishes, algae and other form of harmless microscopic plankton are part of the natural aquatic communities. Fishes play a very vital role in controlling some unwanted insects like mosquitoes, snails, worms and even algae that grow on the wall of the pool. The bio-pool only required small quantity of small group of fishes.

GAF: Can bio-swimming pools be easily maintained?

NKH:  The maintenance of the bio-pool is very minimal. The main back-bone of the bio-pool is the bio-filtration system. The bio-filtration system itself requires minimal maintenance other than a regular check on the operating pumps and the physical filters. Removing excessive algal growth is necessary in the early stage of the pool until a balanced control is achieved from efficient running of the bio-filtration system and algae consumption by fishes. Other routine as part of maintenance are water quality and fecal coliform tests.

GAF: Do you think bio-filtration should be made mainstream?

NKH: The bio-filtration has been proven to be successful in all our projects as applied in garden and fish ponds in this region. Though its application in swimming pools is new due to the fact that the market is not ready for such dramatic change. Recent awareness among the public on the risk of swimming in chemicalised pool that can be of hazardous to health has raised the possibility of a non-chlorinated pool. The public too must be made to aware of the risk in non-chlorinated pool with possible exposure to contamination of harmful pathogens even though the risk is minimal but preventive precautions must put to practice for swimmers as part of their routine exercise. There is no other more practical and cost-effective ways than to apply the bio-filtration system in a non-chlorinated pool if we are to achieve a low maintenance, clean and clear pool water that can be classified fit for swimming without the application of chlorine.

A private bio-pool. Bali (image credit: Ng Kok Hong)

A private bio-pool. Bali (image credit: Ng Kok Hong)

A swim at the bio-pool designed for Taman Petanu Eco Neighborhood in Kemenuh, Bali (image credit: Ng Kok Hong)

A swim at the bio-pool designed for Taman Petanu Eco Neighborhood in Kemenuh, Bali (image credit: Ng Kok Hong)

Thank you for talking with us!

About Ng Kok Hong

Ng Kok Hong

Ng Kok Hong

Ng Kok Hong was born in Perak, Malaysia and married with three children.

He graduated in both Diploma and Bachelor Degree in Fisheries and Marine Science from Universiti Pertanian Malaysia in1984.

He was involved in commercial freshwater aquaculture especially in the production of the giant freshwater prawn for 10 years. During that period, he experimented and applied the bio-filtration system in ponds effectively.

He later involved in recreational lake design and management along with garden ponds in the property and resorts industries in South Asian region.

His work in promoting healthy water garden management without the application of toxic chemicals has given him many opportunities to work with renowned architects.

He emphasizes on education and sustainable design that enable him to involve further into landscaping, bio-pools and his recent promotion of domestic aquaculture with re-cycle organic wastes.

His enthusiasm in art inspired him to design and procure original garden sculptures into his garden design.

He is 53 years old and a deaf who is based in Kuala Lumpur.

A few selected list of water garden and recreational lake projects:

1. Desa ParkCity, Kuala Lumpur. A 5-acre lake

2. The Glades, Kuala Lumpur. A 3-acre lake

3. Kayu Manis Resorts and Spa, Bali. Bio-filtered water garden

4. St. Regis Resorts and Spa, Bali. Bio-filtered water garden

5. Nikko Hotel, New extension. Bio-filtered water garden

6. Novotel Coralia, Bali. Bio-filtered water garden

7. Pranna Hotel, Mahabalipuram, India. Bio-filtered water garden

8. Mahi Estate, Hyderabad. 3-acre lake

9. Convention Hotels, Goa, India. Bio-filtered water garden

10. Taman Petanu Eco Neighborhood, Kemenuh, Bali. Bio-pool


Website: www.ayermatahari.com

Facebook: www.facebook.com/rimbastudiokl

Email: mailto:kokhong50@gmail.com or  mailto:ayermatahari@gmail.com

About the author

Devisanthi Tunas is the co-founder of www.greenasiaforce.com, an online platform which promotes sustainability awareness and green building solutions in tropical context. She is a Singapore based architect.