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A search of the literature has resulted in several possibilities for the identity of the phenomenon known as "pink slime". Recent studies in the field of microbiology have led to the creation of a new genus, Methylobacterium. This genus encompasses many organisms which were previously classified as other genera, including several species of Pseudomonas, Bacillus, Flavobacterium, and others. The characteristics of these organisms are that they are pink-pigmented, gram-negative, non-fermentative, usually non-vacuolated, facultative, methanol consuming bacteria. Also, the majority form a slimy coating which provides an unusual level of protection. Studies have been conducted on several of the species within this group that show the resilience of these organisms against halogen-based sanitizers or germicides. In general, they are prevalent across a wide spectrum of media (biological and environmental) and they have a tendency to remain a contaminant even after a heavy dose of germicide has been used and their CFU/mL count has dropped to acceptable levels. A small quantity in any source (e.g. tap water or plastics) can lead to quick re-establishment of the problem.

 

Treatment of the phenomenon must be quick and total. Several factors may lead to a situation which is favourable to an outbreak of this organism. The most likely source is a person who is infected and who enters a pool or spa. This essentially inoculates the pool or spa, its environs, and all who frequent it. If the pool does not have sufficient sanitizer to control it, the organism will multiply quickly. Crucial to this is pH. The pH must be lowered at the same time as sanitiser is added in order to ensure its successful functioning. At pH above 7.4, the percentage of free available chlorine (FAC) decreases until pH 8.0 at which point it has almost no effect against Methylobacterium. At pH of 7.4, the HOCl molecule is 98% effective against the bacterium. FAC must be raised to at least above 3 ppm in order to be effective. Brushing is absolutely necessary with this organism due to its ability to form a resistant slime coating. This coating must be removed physically by hard, determined brushing and scraping. Any objects near the pool or that have been in the pool must be scrubbed and soaked in a chlorine solution.

 

This is especially true of all PVC products, as the bacterium has an affinity for the matrix that exists on the surface of PVC. The bacterium will attach itself to and inside the matrix, allowing it to recontaminate long after it appears that it has been destroyed. This includes pool toys, floats, ladders, steps, fountains, and the parts of automatic pool cleaners. The latter are particularly susceptible if they come with a floating tube device. The bacterium may adhere to the Styrofoam floats.

 

Pink slime occurs in both halogen or non-halogen maintained systems. The incidence is greater in non-halogen systems and remedies for non-halogen systems are few. One major factor for almost every pool experiencing pink slime is an area of slowly moving water. This may be exacerbated by lack of proper surface cleaning. In another industry, medical technology, slime forming organisms occur in tubing. Research work in this industry has found the need for 500 times the dosage of an antibiotic to kill cells which have attached and formed a biofilm as would be needed to kill a free-floating cell.

 

Treatment of Pink Slime

1. Look for the area where the growth may have begun. Thoroughly brush and clean this area.

2. Disassemble and thoroughly clean the filter.

Sand: Remove the sand. Remove, brush, and clean the laterals. Brush and rinse out the interior of the filter. Replace the laterals and sand.

DE: Remove and discard old DE Remove grids and rinse with a strong stream of water. Place grids into a plastic garbage can containing a chlorine solution (120 mL of bleach per 4 litres of water) and allow to soak for 30 minutes. While grids are soaking, brush grid holders and interior of filter housing. Rinse well. Remove grids from solution, rinse again with a strong stream of fresh water. Reassemble filter. Cartridge: Remove cartridge and discard. If you want to want to keep this cartridge, rinse with a strong stream of fresh water. Place the cartridge into a plastic garbage can with a chlorine solution (120 mL of bleach per 4 litres of water). Before placing the cleaned or new cartridge into the filter housing, brush and rinse the filter housing.

 

NOTE: FOR NON-HALOGEN SYSTEMS: BE SURE TO RINSE ALL ELEMENTS THOROUGHLY BEFORE RECONNECTING TO POOL SYSTEM IN ORDER TO PREVENT COMPLICATIONS BETWEEN NON-COMPATIBLE ELEMENTS (CHLORINE AND BIGUANIDE).

3. Clean by brushing the skimmers, ladders, steps, and light niches. Give special attention to corners,

cracks, and crevices.

4. Brush entire pool surface with a surface-compatible brush.

5. For halogen based pools:

  • With pump running, pour 60-150 mL of Back-Up into each skimmer.
  • Turn off the pump.
  • Pour 1 litre of Back-Up per 40,000 litres of water around the edge of the pool.
  • After 12-24 hours, pour Burn Out 35 into the water around the edge of vinyl, painted, or fibreglass pools (2 bags per 30,000 litres). For gunite pools use two bags of Burn Out per 40,000 litres of pool water around the edge.

6. For non-halogen based pools:

  • With pump running, pour 60-150 mL of quat-based algaecide into each skimmer.
  • Turn off the pump.
  • Pour 1 litre per 37,000litres of Soft Swim around edge of pool.
  • After 12-24 hours, turn pump on again. With pump running, triple shock the pool with 11.5 litres of Soft Swim C per 37,000 litres of water by slowly adding one gallon of Soft Swim C into each skimmer and distributing the remainder directly into the pool.

 

The above information is supplied by Bio-Lab and represents its best interpretation of available technical information at the time of preparation. The sole purpose is to supply factual information to Bio-Lab customers. It is not to be taken out of context nor used as support for any other claim not made herein.