Bioslime III Background

Pink Slime, Clear Slime, White Water Mold, Gray Water Mold

What is Bioslime?

The industry’s two largest swimming pool water research labs (Biolab and Baquacil) have spent well into six figures trying to learn how to prevent bioslimes and how to cure them.

First, some background:

What’s the problem? 

Bioslime is a generic term for various growths that protect themselves from environmental predators by secreting a polysaccharide coating around themselves. The coating feels slippery to the touch – hence the name.  The actual growths may be bacterial or fungal, but we don’t know of any that are actually algal – though our customers always seem to think they are an algae.  In color we’re used to seeing them as white, gray, clear, or pink.

These organisms often grow well in the dark.  They are common in bathrooms (pink slippery stuff along tile grout), in birdbaths, inside oil wells and oil pipelines, and inside medical catheters.

Since the polysaccharide coating protects the actual organism from normal doses of chemicals (including poisons) they are very difficult to kill.

Frankly, swimming pools are much like people. Some are always healthy. Some are sickly. Generally (but not always), people who diet and exercise are healthier than those who do not. Well-maintained pools usually do not catch “diseases” (algae, cloudy water, bioslimes, etc.) However, it can happen to anyone.

Also, there are periods (outbreaks) when some diseases are common (Hong Kong Flu, Asian Flu, etc.) and then they become less so.  It’s the same with swimming pool “diseases”. Some years there’s a lot of mustard algae, or black algae, or cloudy water. After two or three years of problems, they just go away. It’s the ecosystem at work.  We’re hoping that pink slime is following that pattern—and that last year was the worst outbreak we’ll ever see.  However, just in case, we’re still working on a solution.

What Causes it? 

Contaminated equipment (solar cover, vacuum hose, etc.):  Since these spores are part of the environment, any equipment left out and not cleaned may become contaminated.  When the equipment comes into contact with the pool, the spores end up in the water and propagate under the right conditions.

Dirty filter:  A dirty filter is an excellent breeding ground for water mold or other microorganisms because it provides a source of nutrients necessary for growth.  Unlike algae, water mold and bacteria do not need sunlight to make food, so the filter is an ideal location. In some cases, biofilm may coat the hair and lint basket, skimmer and plumbing.

Poor circulation:  water mold or slime is also found behind underwater lights and ladders, or other “dead spots” in the pool.  It will attach itself to an area and remain there until it is physically removed.

Chemical system misuse:  When your three-part system is not followed, the pool becomes vulnerable to a variety of conditions such as water mold and pink slime.

How do I know if my pool has it? 

If you live in the northern, eastern, or mid-western portions of the United States, you have it. The real question is, do you care?  Roughly 93% of you don’t care. E ither you don’t see it, or you don’t look.  It really doesn’t matter, it’s not bad for you, it’s in your drinking water (normal levels of chlorine do not kill it) and it’s in the air and the rain.

So who does care?  People who do not want to see it growing in their skimmer, inside their ladder, inside their underwater light, etc.  Plus one very important group: people with cloudy water that just won’t clear up.  Unfortunately a really bad case will make the water very cloudy.  Most cloudy water treatments (cleaning the filter, improving circulation, clarifiers, flocs, filter aids, etc.) make only small improvements in these cases.

How do you know that’s your problem?  You don’t.  There’s no test for it.  Even seeing it in the skimmer doesn’t tell us that’s why your water is cloudy – it could be a coincidence. So first, we try all of the normal “cloudy water” cures, because cloudy water is way more common than bioslime.  If they don’t work, then we suspect bioslime.

We also look at how long shock can stay in your pool.  If chlorine shock drops to 3.0 ppm inside of six hours of sunlight, if Softswim C drops to 10 ppm within 2-3 days, or if Baquacil shock levels drop to 30 ppm within 2-3 days, the problem may be bioslime. Remember there’s nothing wrong with readings that low.  Shock is supposed to drop.  It is only the speed of the drop that is interesting.

What’s the cure? 

Early research indicated that bioslimes were associated with swimming pool water that is low in calcium.  The pink and clear ones seem equally likely to happen in water that has been treated with chlorine, bromine or biguanide.  The white and gray ones seem slightly more common in biguanide pools, but probably because a good number of those pools used simazine algaecides and didn’t use winter kits.  All of the bioslimes seem to be more prevalent in pools that are not shocked often enough, or (for an as-yet unknown reason) shocks don’t last very long in the pool water.  Often, the growths start in the pipes, hoses and filter – the opposite of algae, which always starts in the sunny area of the liner.

To prevent them, we’ve been advising keeping your pool water balanced – especially before it’s closed for winter.  Use a filter cleaner twice a year.  Shock regularly.  Whenever you refill the pool, run 20-30 gallons of water from your garden hose out onto the ground before putting it into the pool. Bioslimes are usually in your drinking water (in small quantities) but they grow very well in a hose sitting in the sun.  Brush the pool often – especially under ladder treads, under the skimmer weir door, and under any folds or flaps in the liner.

Research also indicates an association between high total metal and mineral levels and bioslime growth.  Unfortunately there are many more metals and minerals than we have the ability to test.  Also, several metals at lower levels than we can effectively test could add up their total level to be a problem. (10 x 0.2 ppm = 2.0 ppm).  It would be a good idea to add an additional dose of metal or mineral control product upon opening each year – regardless of any test results that may not indicate such.

All equipment that comes in contact with the pool should be cleaned after use and stored away from the environment.  This will help prevent infection from spreading to the pool.

The filter should be cleaned at least two times per season to destroy any nutrient source available for the water mold.

Check the circulation pattern to be sure the returns are directed toward the bottom and away from the skimmer in a circular flow pattern.

Any leaves, dirt or debris that accumulates in and around the pool, skimmer and hair and lint baskets should be removed as quickly as practical.  This debris provides a nutrient source and a possible breeding ground for water mold.

The pool should be brushed on a weekly basis.  Cleaning should include the steps, behind ladders, underneath slides and diving boards, and the waterline and skimmer areas.

Correctly following your three-part chemical system will minimize the opportunity for water mold or pink slime to appear.

It does appear that bioslimes are a growing environmental disease. They do not hurt anything.  They are not harmful, and town drinking water systems are making no effort to control them.  In fact, one reason for the increase in bioslimes in homes (especially bathrooms) and swimming  pools is that municipalities across the country have been switching to cheaper ammoniated forms of chlorine in their water treatment process. It saves the taxpayer money, it seems to work about as well in killing E-coli and other harmful bacteria, but it does not kill the bioslime in the water pipes as well as the more expensive forms.

Please let us help you, anytime.                                                                                        Revised:  5/20/08

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We write Pool Tips^™ for the exclusive use of our own local customers. They are meant as a summary of general information, to be discussed in our store, with our staff, to determine which items are best for specific pools. Pool Tips^™ are a trademark of Gull Group, Inc. All rights reserved.

Our suggestions assume that you have given us a proper description of your pool’s size, history and symptoms. Sometimes we can figure it out, sometimes we can’t. Your doctor has years more training, far better diagnostic tools, and makes way more money—and sometimes he or she gets it wrong, too.

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