How To Get Rid Of A Fishy Smell In My Swimming Pool?

Lady holding a fish with her nose pinched closed with a closepin.

Have you ever started to take a swim only to ask yourself “What is that fishy and nasty smell coming from your swimming pool”?  I know I have and at first I didn’t know what had gone wrong.  After some research and testing of my pool water it didn’t take me long to figure out the culprit and get rid of the stink.  I will share what I did to remove the fowl and fishy odor from my pool and turn it back into a pleasurable oasis once again.

The top reason your swimming pool may smell fishy or fowl is lack of proper sanitation.  First you should check your swimming pools chlorine levels and see if they are low.  If you find your chlorine levels are below normal readings, you may need to start adding more chlorine on a regular basis.  Either way the best thing to do is shock your pool to bring your chlorine levels to a high level to kill any bacteria or chloromines that could be thriving in the pool water.

Having your chlorine levels at the recommended levels of between 1 ppm and 3 ppm is best.

Also while maintaining these levels you still need to shock your pool about once per week especially in the heat of the summer, after heavy rains which dilute the water and lower your chlorine.

Lastly when you begin see algae, cloudy water or begin to smell a funny or fishy odor coming from the pool it is likely time for a pool shock treatment.

Check out my other article I have on shocking your pool regularly to keep your pool clean and clear.


I have put together a list of some of the top reasons your swimming pool may encounter an unpleasant odor.

  • Your swimming pools needs sanitized.  This can be due having too little chlorine in your pool water.
  • You need to shock your swimming pool.  If your chlorine levels are within the recommended range, shocking your pool is still necessary and may quickly remove the odor you are experiencing.
  • Ammonia levels are too high.  Sweat, urine and other bodily waste that may come in contact with the swimming pool creates ammonia.  Also fertilizer used on your lawn, wildlife such as birds, squirrels or any other animals that may enter your water can also cause these levels to increase.
    • Once again shocking your pool will kill the ammonia and bring your levels back to normal.  This is one of the reasons shocking your pool weekly is key to keeping your water clear and fresh all season.
  • Nitrogen levels are too high.  The causes of excess nitrogen components in your pool is very similar to that of having excessive ammonia levels.  Perspiring, waste and other contaminants in the water can raise nitrogen in your pool
  • Not opening or closing your swimming pool at the proper time.  If you are experiencing a fishy odor at the beginning or the season which requires a week or more of work to open  your swimming pool, you probably opened it too late or closed it the previous season too early.
    • I have written an article on this exact topic in the past.  You can find it here as it explains how I determine when to open and close my swimming pool.  if you open it too late, algae and bacteria will begin to grow and the same applies if you shut it down too soon.  This would definitely result in a fowl smell and possibly a green pool early on in the season.
    • Opening and closing your pool does not mean it is time to swim, it simply means it is time for maintenance and keeping it prepped and clean for instant swimming once the water and outside temperatures are warm enough.
  • Dead rodent or animal.  This is not likely, however I have seen it first hand.  Be sure no animals may have fallen into your water and died.  There are trees that are close to my swimming pool and a couple seasons ago a squirrel fell in my pool during the off season and died creating a smell in my backyard until it was removed.

Low chlorine levels can be caused by increased temperatures, above normal rainfall or storms and improper regular maintenance.

I have experienced pool odor from time to time in my pool. The first thing I always do is shock the water overnight when the sun is down and generally by morning when I wake up the odor is reduced or completely gone.

Remember when you are shocking your pool, you can add a higher dosage than what the manufacture recommends.  I also like to add about 1.5 times the regular amount of shock I would normally use if the water is needing extra attention.

You cannot overdose your pool with shock, however you will need to wait longer before you and your friends enter the pool.  Test the water and wait until the chlorine drops under 5 ppm and you can safely re-enter the water.


Adding shock to the swimming pool.

The easiest and most common way to remove smells of any kind from your swimming pool is raising chlorine levels fast by shocking the water.

Shocking your pool will kill any bacteriaalgaenitrogenammonia as well as other livingorganisms that may be present in your pool water.

Total Chlorine = Free Chlorine + Combined Chlorine. 

This is also true if your swimming pool starts to smell of high chlorine levels.  Once in awhile during the season while swimming or even outside of the water you may notice you smell the chlorine more than usual.  This is usually due to your total chlorine levels being high which is different than free chlorine levels which is what most people test when checking chlorine levels.

When you shock your pool it will help bring the total chlorine levels back down and rid the smell of excessive chlorine coming from you pool.

You will need to however add about 10 times the free chlorine than the amount of combined chlorine currently in your pool for the combined chlorine to be removed.

This is called super shock or super chlorination.  Either have your water tested at your local pool store, or perform a combined chlorine test to determine this number.  No swimming should be allowed when super shocking your pool.


If you are on this article it may be too late, but preventing odors can be done easily by proper pool maintenance before, during and after swimming season.  The best way to make sure you water stays clear and odor free is to have a routine schedule that you follow each week.

  • Commit one day a week to test your pool water.
  • The same day you test your water, add chemicals necessary to maintain the pool.
  • During the hottest time of the season you may notice your tests vary.  For example your chlorine levels may be lower than normal.  Use this as a cue to increase your weekly dosage until the weather cools back down.
  • Keep your pH, alkalinity and chlorine levels in the proper range.  It is important to check all three of these each week to ensure your pool stay healthy.
  • Most importantly shock your pool once a week.  I would recommend doing this at night and commit to the same day such as the day in which you run all your tests.  Also consider shocking after a heavy rainfall especially if more than an inch of water has fallen quickly.

If you commit to a plan and stick to it you will prevent odors, algae and other unwanted obstacles getting in your way.

Also take notes and you will learn after a couple seasons of routine pool care when you should…

  • Increase maintenance dosages based on weather temperature, rain and storms.
  • Shock your pool outside of your normal schedule based on the look of your water, odor or tests performed.
  • Begin to notice certain signs allowing you to become an expert at your swimming pool.  Once you learn your pool like the back of your hand, you and all your guests will be amazed at how your pool looks all season long.

Plus you will not have those few times or more each season when it takes an amazing amount of energy, work and money to regain control of your swimming pool due to improper maintenance.

As well as never being embarrassed by a surprise visit from friends that would like to jump in for a seasonal swim. 

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