How clear should the water be?


LifeTime Supporter
May 15, 2007
New Jersey

Just wondering how clear the water should be. I know the clearer the better but if you go underwater and open your eyes is there any way to judge if is clear enough? Example might be you see a piece of a leaf in the go down to get it but you open your eyes and all you see is a brown blotchy area...not clear. Does that mean the water needs a clarifier if all other tests are within the correct parameters. Just a thought I had today....yes while picking up that brown blotchy part of a leaf!!!



Well-known member
May 23, 2007
I'm pretty much a pool newbie, but I'll try and chime in :)

You rarely (if ever) need a clarifier, I think some people use it after doing some treatments to remove metals from their pool, but thats about it.

I think there are quite a few reasons your water could be cloudy, but the two things I would do in your situation are this:

1) Test your water and get detailed results, people here are great, but they are even better when they get water testing results :)

2) Shut your pump down for 24 hours, and see what happens to the clarity. Our pool was really cloudy until we did this, and vacuumed all the "stuff" on the bottom to waste with a vacuum hose. You can now see the bottom quite clearly


LifeTime Supporter
May 15, 2007
New Jersey
to add to my post..

My water is clear when you look at it from anywhere. Just wondering if it should also be clear when you open your eyes underwater. Just put in a new fiberglass pool and my test results are getting closer to appropriate ranges. Testing tomorrow so I will know what I need to do if anything. Just was a thought...I remember as a kid swimming and opening my eyes and seeing with no problems...or maybe it is just something I think I maybe I was just in the water way too long today!!!



LifeTime Supporter
Mar 29, 2007
SE Louisiana
Things will always look blurry if you open your eyes underwater; even if it were distilled water. A better test of water clarity is looking at the bottom from the surface. You should be able, for example, to see details on the main drain like screw heads. You can also look underwater while wearing a mask or goggles. Finally, the amount of stuff you can see in the vicinity of your pool light, at night, is a pretty good indicator of clarity.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
The difference in the index of refraction between air and your eye vs. water and your eye is why things look blurry underwater. Essentially from a focusing perspective, everything you see underwater is as if it is very, very close to your eye (even though it may not quite appear that way). When you are younger, you are able to focus on objects that are much closer to your eye than when you are older. This is because your lens gets stiffer and the muscles that change the lens shape get weaker so the net effect is that you can't change the lenses focus position (diopters) as much when you get older. This is why you need reading glasses, usually in your mid-40's or so, because that's when the limit of focus is around the distance of normal reading (12"-18"), but the change occurs all of your life with a 5-year-old being able to clearly see an object only 2.5" away from their eye. Using goggles (a mask) underwater makes the vision more normal since the eye is exposed to air while the water is seen through plastic that minimizes the effect of change in the index of refraction (plus such change is moved away from your eye so has far less effect).

I found the following to be an interesting table showing the rough closest in-focus viewing distance vs. age. The following assumes perfect distance vision, but would also apply to someone wearing glasses that give them normal distance vision.

. 5 ....... 2.5"
10 ....... 2.8"
15 ....... 3.3"
20 ....... 3.9"
25 ....... 4.6"
30 ....... 5.6"
35 ....... 7.2"
40 ....... 8.8"
45 ...... 11.3"
50 ...... 15.8" (1.3')
55 ...... 22.5" (1.9')
60 ...... 39.4" (3.3')
65 ...... 78.7" (6.6')
70 ...... 157" (13.1')
75 ...... 378" (31.5')



LifeTime Supporter
May 15, 2007
New Jersey
wow....very interesting..

They are pretty interesting facts. Stinks getting older in so many ways. Time to break down and buy a mask to bring back those younger years and who can resist the rings they leaver around your

Thanks for the quick replies...hopefully my next brainstorm is a little more worthy.

I am a newbie but learning quickly....hopefully I can help others eventually.

PS...the fiberglass pool is glad we decided on it.



LifeTime Supporter
Apr 24, 2007
Ashland PA
I think the whole eye thing is the universe being very kind to us - as we age, when we look at ourselves :- we can't see our wrinkles very well :-D , Unless we put those little glasses on :shock: