Microorganisms of all types can grow in a poorly treated spa.  Sanitizing is the only thing that keeps spa water clean, healthy, enjoyable and from becoming old bath water.  Microorganisms including algae, bacteria, slimes and mold can present themselves in various ways:  cloudy water, slimy growths or slippery underwater surfaces.  The warm temperature of the spa or hot tub can accelerate the growth of microorganisms.   Today, there are many more choices of spa water sanitizers:  chlorine, bromine, biguanide, ozone ultraviolet, mineral purifiers and ionization.  Using a combination of two - one as the primary and another as a backup - produces consistently good results and sparkling clear spa water.  Proper spa water treatment has never been easier or more convenient.  Clicking on the underlined and highlighted "keywords" or "catch phrases," in the archived answers will give you access to additional information on that topic or product.  Please refer to the Glossary, if there are terms or phrases that require explanation.

► Black Growth?

Alan, I have a  hot tub and I use a product that doesn't contain chlorine or bromine, instead of chemicals.  I am getting a black growth that neither the tub dealer nor the treatment manufacturer can identify.  I have treated, drained & cleaned the tub twice, and the problem returns.  I have not treated with a chlorine type shock yet.  On advice from the tub dealer, just the treatment's brand of shock.  Have you ever heard of a black type of growth?  Do you know of a lab where I can get it tested to identify it?  Should I use a chlorine (or other chemical) based shock to completely get rid of the growth (how much and how long)? Thanks.

Phil J., West Virginia, 4/22/2003

I am not sure what this product is, but it doesn't seem to be working for you.  I suspect that it is some type of natural enzyme product.  Does it have an EPA Registration?  If it doesn't, as I suspect, it is not recognized as a spa water sanitizer.  You didn't provide much information as to whether or not the spa has an ozonator or mineral sanitizer?  The product that you are using may provide acceptable results to a point.  Eventually, a microorganism will start growing that is resistant to this product's action.  Yes, I would try using chlorine to destroy the growth.  Add enough chlorine to boost the Free Chlorine level to 5-10 PPM and keep it there until the growth is completely gone.  Afterwards, you can return to normal maintenance.  However, if this growth is truly resistant to the product you are using, the problem will return with near certainty.  I suggest that you use a more conventional spa sanitizing system.  Browse through the "Ask Alan" archives for more information on other sanitizing choices.  There is a possibility that the problem is not a microorganism.  It the chlorine fails to remove the problem, have the water tested for iron, copper, manganese and other heavy metals.  I hope that I have been helpful.  Good luck.

Sincerely.  Alan Schuster, 4/22/2003

► Possible Spa Water Mold Problem?

My husband and I have a 2004 model spa.  Right before we changed the water the last time (2 weeks ago) we noticed these little wisps floating in the water.  They range from 1mm to 5mm in size, feel slimy when touched and are pinky-orange-brown in color.  Also, they smell.  They are most noticeable after the pumps have run and then shut off.  It almost looks like someone dropped a piece of tissue paper in the water and it has dissolved into these little bits.  We have cleaned the spa and flushed the lines twice (got lots of green algae out of the lines too), but this problem came roaring right back after the spa was running only two days.  This stuff dirtied up a filter in less than 36 hours.  Help!  Sincerely.

Rachel A., 4/18/2005

What you are describing sounds like mold and bacterial growth.  Your ozonator may not be operating properly or for long enough periods of time.  Ozone should be detectable by odor, upon removal of the cover and can be tested for using a test kit.  You need to verify that the ozonator is working properly.  Ozone requires a backup sanitizer such as chlorine, bromine or a mineral sanitizer.  Are you using a backup sanitizer?  If not, I suggest that you consider using bromine.  An operating ozonator will allow you to maintain a lower than normal level, by adding reduced amounts of bromine.  Try and keep the level at 1-3 PPM.  Make sure that the ozonator is operating for at least 4, 2-hour periods spaced throughout the day.  To help jump-start things, add shock treatment to help destroy any mold or bacteria and help establish a bromine level.  I hope this information will prove to be helpful.

Sincerely.  Alan Schuster, 4/19/2005

► White Mold?

I have been told that my hot tub has white mold in it. Is this a serious health problem to the tub users.  Me and my family?  I was offered a chemical for ridding the pipes. It's pretty expensive and somewhat drastic looking. Any recommendations?  Thanks so much.

George, 6/13/2006

This type of mold problem is usually indicative of the development of a resistant microorganism and/or inadequate sanitation. Some more information would have been helpful.  If you are using biguanide, you should permanently switch to another sanitizer.  If you are using chlorine, I suggest that you switch to bromine.  Bromine seems to be the most effective treatment for this problem.  You can add sodium bromide and non-chlorine shock (the 2-part bromine system) and boost the bromine level to 5-10 PPM.  Keep it elevated until the problem is solved.  After the mold is eliminated, you can continue bromine additions with either the 2-part system or bromine tablets. You could add a large dose of chlorine and really get the level up (20 PPM).  This will clean out the pipes and the filter.  Afterwards, drain and clean the spa.  Refill and start off fresh.  The addition of an ozonator is something that you might consider, as it will make maintenance easier and produce higher quality water, with more consistent results.  It will reduce the chemical consumption.  You might add a mineral sanitizer, as well.  The combination of the two work well together.  All you should need is a very low level of bromine, as it will act as confirmation that proper conditions are being maintained.  I hope that I have been helpful.  Enjoy the hot tub.

Sincerely.  Alan Schuster, 6/13/2006

I believe I am suffering from a white mold infestation. Here's the background. I've had my spa for 6 months, as of 3 months ago I noticed what looked like white flakes floating in the water. I can best describe it as what it would look like, if you put paper in the water and broke it down into fibers. I originally thought it was organic in nature and raised the bromine level to kill it off. When it didn't happen, I drain it, scrubbed it and refilled. It took 2-3 days, but the flakes returned. After some research, I thought it might be a hardness problem. The local water is somewhat high. Today, I'm back at thinking the problem is organic in nature. From several sources, professional, friends and the web, I have been told that white mold is probably the culprit. The mold is fairly resistant to bromine and chlorine. Sunlight is an effective agent against it, but the mold, within the pipes, is protected. Making the problem go away appears to be very labor intensive and sort of hot or miss. My question is what can you tell me about this problem/situation? I sincerely appreciate all feedback. As for specific: I use bromine and there is a functioning ozonator. I drain and clean, in accordance, with manufacturer specs. We don’t use it that much now (3-4 times a month), but it has been used heavily in the past. It can go a month without use. After use, I typically shock. The amount increases, if my kids use it or we have friends over. I clean the filter every 3-4 weeks. The current filter is 8 months old. It has never been dry. Even if it is not used, I watch the chemicals to make sure they are in spec. Thanks. However, test strips showed total alkalinity to be within specs or at least abnormally high. Today, I'm back to thinking the problem is organic in nature.

Pete N., 5/1/2007

► Probably Algae, Bacteria And More?

We were gone for the entire summer and the spa was left with only a bromine floater.  It now looks like yuck!  What do you suggest?  Thanks for the help.

Ken G., Fayetteville, NC, 9/23/2004

I suggest that you start draining the water and do some rinsing with a garden hose.  Clean out the filter and replace. Refill with fresh water and add a double or triple dose of a quick dissolving chlorine or non-chlorine shock.  Make sure that the pH is 7.2-7.6.  Keep the Free Chlorine level high and the filter operating.  Retest frequently and add more shock, as required.  Eventually, the chlorine will destroy all of the "yuck" that developed on the walls, in the plumbing, in the filter and in the nooks and crannies.   When things clear up, empty the spa and rinse off everything in sight.  Now, you are ready to start from scratch.  For free chlorine testing, I suggest using LaMotte Insta-Test strips, as they provide the right kind of information.  Go to:  www.lamotte.com    To better assure proper overall spa water chemistry, visit a pool/spa store that has a very reliable, professional lab such as a WaterLink or Pinpoint system, rather than a less accurate test kit or strip reader.  To locate a dealer near you, go to:  www.lamotte.com/pages/pool/expdeal/index.html  I hope that I have been helpful.  Good luck.

Sincerely.  Alan Schuster, 9/23/2004

► White Water Spa Mold?

► Noah's Ark?

I have been very, very bad.  And have let my anxiety about pool care get me into a situation.  I have a fiberglass swim spa and have not been monitoring the chlorine levels, nor circulating enough, thus the green tinted water.  I also was afraid to change my cartridge filter.  So, this is where I am now.  I changed the filthy, dog-hair, algae, ridden cartridge filter, shocked the pool with chlorine, vacuumed the pool and brushed the pool.  The water is blue again now.  I still have foam, which is probably the algae being killed by the chlorine? and stained steps which brushing with all my might won't remove.  Question #1:  Will using muriatic acid on the old cartridge filter clean it enough to use again, or should I buy another new filter?  Question #2:  How do I get the stains off the steps near the return when they are under water?  My telescope bristle brush is not doing it!  Question #3:  Is the foam I mentioned above, a natural algae killing result?  My other levels in the pool are OK except for low pH at this time.  I'm not sure if I should add pH rise at this time or not?  I am learning the hard way!  Please help!

Pat T., 4/8/2007