Automatic dosing is essential for efficient pool management….
The equivalent of switching to cruise control in your car, or even driver-free for the most advanced systems, automatic dosing is not a new phenomenon but never has it made more sense. Not only does automatic dosing offer more economic pool management, it is safer for staff, owners and bathers and it demonstrates duty of care. “Understanding the benefits of auto dosing is not hard when we look at what it truly represents,” points out Prominent’s Stephen Ellix, also an active member of the Pool Water Treatment Advisory Group (PWTAG). “If you were able to have a full time employee, standing with chemistry ready to dispense, checking the values of the chemistry within the pool water, 24 hrs a day and 365 days a year, one could argue that, auto dosing is not required. “I am not sure as to the cost of this employee, but if you need the best of chemical consumption and the best levels of chemistry within the pool water this is the level of control or auto dosing required. “This level of continual monitoring and injection is what we see when using auto dosing,” he emphasises. “The reality of auto dosing is now as important as it has ever been with economies as much as a 15 per cent reduction on chemical usage. “Bather loading can now be measured at the till,” Stephen continues. “Circulation pumps can indicate flow demand, and chemical levels from the day tanks can be relayed to your mobile phones or even SMS texting to advise service requirements.”
To appreciate the benefits from today’s level of auto dosing, Stephen believes, it is best to look at the effectiveness of the current three types of control when looking at the systems capability in maintaining the best of values for the best of water quality.
1. Continual Manual Dosing: This is a blind approach where the doing pump is switched on when there is a flow within the plant room of the pool water. The dosing pump has no idea if the chemical is required or not. It is purely dosing in proportion to flow and not on the demand. If you have one bather or two hundred the pump will pump the same amounts.
2. Timed Control On/Off: A blind system but with the benefit of some form of calculation that offers just a little more control than continual manual dosing. It is still unaware of the actual requirement or demand.
3. Proportional Control: This is where the control, in using sensors, make an appearance and offers the first level of control that is looking at the demand for chemical within the pool Water based on pre-set values and levels of water contamination being measured.
Stephen explains: “Proportional is more akin to a cruise control of 10 years ago while proportional–integral–derivative’ represents a point of almost driver-free cruise control. “In replacing our amazing 24-hour a day employee, the only real Auto dosing option is number three,” Stephen reminds us, emphasising the further three industry wide types of intelligence within this auto component of the controller and these are, in basic terms:
• Proportional (P) As it says the sensor registers a requirement and depending on the demand the dosing is adjusted accordingly.
• Proportional–integral (PI) As above but with some calculation within the controller programme to compensate for say the volume of chemical taken to advance the rate of injection.
The controller will start the dosing pump of at a rate and increase that rate if there is a slow response.
• Proportional–integral–derivative (PID) As above but with the ability to compare to process demands. Here the controller thinks about the P and I and then again calculates the required response.
Water treatment and disinfection systems are becoming ever more technology driven and integrated with building management systems, agrees Andrew Gaffey of Gaffey Technical Services. “At the same time, dedicated plant room technicians are becoming a rare sighting these days with many facility operators relying on their pool staff to manage their plant rooms,” Andrew points out. “A dosing and control system that can meet a wide range of technical demands, yet remain simple and intuitive in operation, is an important factor in ensuring smooth facility operation and a stress-free relationship between a service company and its pool operator client.”
The industry standards booklet, Swimming Pool Water Treatment and Quality Standards For Pools and Spas by PWTAG, advises that manual dosing is rarely justified in non-domestic pools, that automatic dosing is best for all pools, and essential for public pools. It goes on to state that dosing systems, like circulation, should continue 24 hours a day in order to maintain stable conditions for bathers. Manual dosing of chemicals directly into a commercial pool presents a number of risks. Most chemicals for water treatment are hazardous to health, and therefore come under the COSHH (Control of Substances Hazardous to Health) regulations. COSHH regulations require an assessment of risks to be done so that risks may be controlled, exposure to the substance minimised, and that operations do not pose a hazard to the health of the operator or to anyone in the vicinity.
Jimmy Lamb of Pollet Pool Group points out: “Manual additions of pool chemical probably means exposure to the operator carrying out the dosing, and to anyone else in the vicinity. “It is best to confine the chemical to the pool chemical store and dose the product/s into the circulation system in the plant room,” he adds. “Safer, more efficient, use of chemical is achieved where the dosing of chemicals is continuous and satisfactory water quality is more easily maintained,” Jimmy emphasises. “It is usually more economic too, as with manual dosing over and under dosing is common with the resulting waste of chemical.” Over and under dosing can cause unsatisfactory water conditions in that overdosing gives uncomfortable conditions for bathing with possibly bleached costumes, skin/eye irritation etc., whereas under dosing can allow organic pollutants to survive. Jimmy says: “As the pool is being used, any chlorine in the pool is dissipated by the bathers and the pH will change. “In order to maintain satisfactory hygienic conditions it is necessary to replace that lost chlorine and control the pH as quickly as possible. This cannot be achieved by manual additions. “It is not possible to manually dose chemical while the pool is in use. It follows, therefore, that the loss of disinfectant (chlorine) cannot be replaced nor can the pH be controlled within the acceptable range during the bathing period. Unsatisfactory conditions could prevail with the risk of transmission of waterborne disease.”
There are benefits to automatic dosing systems for both parties, as Golden Coast managing director Jamie Adams explains. “As we’re all aware, chemical dosing can be a minefield for owners and operators alike. Because it’s so easy to get it wrong, absolute vigilance is essential. “For those who own home pools this can be a real issue. After all, would you rather spend your time testing, measuring and risking your water quality, when you could be simply relaxing and enjoying your pool? Automatic chemical dosing allows them to go ‘hands-free’. “And for operators, the expertise and hours necessary to ensure safe water quality is just too costly. For this group, however, automatic dosing is more of a requirement, than necessity.” Automatic dosing systems allow operators to eliminate valuable staff-time spent testing, avoiding dosing mistakes and – above all else – ensuring water is clean, clear and hygienic at all times. Jamie continues: “But, it does require a commitment from employers and facility managers to increase staff knowledge and understanding of the subject through appropriate training… and that can come at a high cost.” Vanessa Lloyd, Certikin’s Certichem Product Manager agrees: “There are so many out there that do not understand the kit they have and how and when they should be interacting with it. Even more alarming is the lack of awareness of guidance in relation to its safe operation.”
“The CertiDos team encounters this type of scenario frequently,” Vanessa reveals. “The kit has been carefully selected, the job goes without a hitch, the operator couldn’t be happier and then the call comes six months later. “The system hasn’t been touched since day one and now it’s ‘fallen over’. It’s a disaster because down time isn’t an option and they need our immediate assistance,” she points out. “Fault finding is always a challenge and at times, it’s not long before the situation has gone from being positive to negative. “We see our role as facilitating our trade customer with ensuring the client’s expectations are met and equally, that they are managed.”
CERTIKIN 01993 777200 www.certikin.co.uk
GAFFEY TECHNICAL SERVICES LTD 01254 350180 www.gaffey.co.uk
GOLDEN COAST TEL. 01271 378 100 www.goldenc.com
POLLET POOL GROUP TEL. 01635 227999 www.polletpoolgroup.co.uk
PROMINENT FLUID CONTROLS TEL. 01530 560555 www.prominent.co.uk