Why Do Pools Turn Green?

why is my pool water green this is the

first question that pool owners are

going to be asking if you don't know

what you're doing with your water

chemistry it's a foregone conclusion

that your water is going to turn green

at some point or another and you're

gonna find yourself asking this question

probably going to the Internet first and

so I just want to give you a couple of

things that you can look at right away

that could be the source of your green

water the first and foremost thing

that's gonna come to mind is chlorine do

you have chlorine in your water if the

answer is no for any reason then there's

your answer your water's green because

you don't have chlorine in it well as

soon as you don't have chlorine then you

start to have bacteria analogy and

things like that growing right away in

the water so you know 24 hours later

something like that it would be pretty

easy for your water to go green and so

the obvious answer is you need chlorine

but more specifically you need a free

chlorine account between two to four

parts per million that's the idea you

know one part per million in theory is

enough to get the job done what you

don't have very much of is reserve what

if you get a heavy rain or a bunch of

people go swimming something like that

you're gonna drop down to zero and the

goal is as a pool owner to not let your

chlorine drop to zero you always want

your free chlorine level above zero

ideally two to four parts per million so

what happens if you have green pool

water and you do have a free chlorine

level between two to four parts per

million and that's how you found

yourself watching this video why is my

water green yes I know I need chlorine

I've got chlorine the water is still

green there are in fact a number of

reasons why this can happen and this is

where it starts to get just a little

more complicated with swimming pool

water chemistry because there's a couple

of different things that can result in

you having green water despite the fact

that you have a measurable free chlorine

value in the water the first would be

the scientist in the water now cyanuric

acid is something that you don't

typically deal with day to day with your

chemistry but it is something that also

in pools need it is essentially the

sunscreen for chlorine that's the catch

phrase for sayonara acid basically it's

just at the it's the thing that allows


to stay as a residual in your pool as

opposed to just being degraded and

burned off by UV so if you didn't have

any stabilizer or you had zero cyanuric

acid in your pool then your chlorine

level is gonna be zero by the end of the

day it doesn't matter how much chlorine

you had in your water by the end of the

day it's all going to be gone because

the UV is going to degrade it all and so

you establish a cyanuric acid level

between 30 to 50 parts per million

however if you use stabilized chlorine

in your pool regularly for example

chlorine pucks what that means

stabilized is that there's cyanuric acid

in it and every time that you add a

chlorine puck to the water then you're

adding more stabilizer to the water and

so if you're not monitoring that level

which most people don't regularly it

will slowly climb over time and the

point at which you get around 80 to a

hundred parts per million and certainly

more than that you're going to notice

that the water will turn green despite

the fact that you have a measurable free

chlorine level and it's simply because

you are entering something called

chlorine lock where the cyanuric acid

level is so high that the chlorine is

just not able to do its job properly and

the truth is is that you know when you

get up to 80 or 100 parts per million or

more for cyanuric acid the chlorine is

just largely unable to do its job like

90 percent unable to do its job so you

are left with a situation where you're

measuring a free chlorine level and yet

your waters still turning green you

don't know why check your cyanuric acid

level if it's too high if it's above 50

75 parts per million you need to drain

and refill your water to get it back

down into that 30 to 50 parts per

million range and then you need to

consider the source of chlorine that

you're using for your pool maybe you

should consider unstabilized sources of

chlorine where you won't constantly be

adding cyanuric acid to the water this

is very important if you live in an area

with water restrictions where you're

just not allowed to drain and refill

your pool any old time you want then you

need to be definitely aware of the

sources of cyanuric acid for your pool

but if you're just an average pool owner

your pool water turned green I have

chlorine why well maybe it's a signer

said level that's not something I'm

going to be checking right away but

that's not the end of it there could be

something else like pH for example I

think we all know that pH is something

that you need to balance and swimming

pools however if your pH level gets too

high the chlorine again will be largely

unable to do its job and the point at

which that happens is you know around

8.0 and certainly over eight point two

chlorine is largely unable to do its job

so you you test the water you have a

small free chlorine level of a few parts

per million and yet you have green water

why is it what is the pH of the water

it's entirely likely that your pH is too

high and this would be especially true

for something like a saltwater swimming

pool the type of chlorine that a

saltwater swimming pool generates has a

very high pH and so it's always pushing

the pH of the water up and typically

speaking it's going to be over 8.2 in

most saltwater swimming pools where

people are not aggressively taking steps

to make sure that they keep their pH

down and so you'll find that you have a

few parts per million or more of

chlorine and yet your water is always

green you need to check the pH of the

water because it could be that your pH

is just too high and that your chlorine

is just not able to do its job

so what else could be wrong a really

common thing these days is phosphates

now phosphates in your pool water get

there from detergents or runoff from

fertilizer things like that and in

essence what phosphates are is it's it's

like a superfood for the algae in your

pool water and so you're pouring

chlorine and at one end of your pool and

by the other end of the pool there's no

chlorine left and it's just because the

algae is growing it's such an incredible

rate that it's consuming the chlorine as

fast as you can put it in so you know

you went out there today you put a whole

whack of chlorine in your pool and

tomorrow it's all gone again what's

going on the pool is turning green it

could be that you have phosphates and so

if you are chronically dealing with

green water that's something that I

would check it's not something that's

always tested for like if you just use

test strips or something like that it's

it's not in there and most water labs

don't test for phosphates unless you ask

them to so it could just be that you

have a high level of phosphates and it's


can't note that phosphates are measured

in parts per billion when we deal with

swimming pool water we often deal with

the unit of measurement of parts per

million phosphates are so important that

we measure them in parts per billion and

by the time you get 500 parts per

billion or more of phosphates in your

water your chlorine is already being

readily depleted and you should be

considering doing something about it by

the time you get to 1,000 or 2,000 parts

per billion or more your chlorine is

just being consumed so readily that your

water is green all the time and it

doesn't matter how much chlorine you use

or how fast you pour it in it all gets

used up and you've got green water the

next day again and so that would

definitely be one of the things that I'm

thinking about if I'm dealing with

chronically green water and that's kind

of it from a chemicals perspective what

I'm looking at when I'm dealing with a

green pool but there is also the idea of

filtration filtration is a very

important part of keeping your water

clean and clear and it's something that

I would say typically speaking pool

owners tend to undervalue the name of

the game with pool filtration for the

average pool owner is getting away with

the minimum number of hours running your

pool pump

I understand pool pumps are expensive

they use a lot of electricity that being

said there are established standards for

this kind of thing and what it is is you

need to as the pool owner pump three

times the volume of your pool through

the filtration system every day that is

the minimum standard that will achieve

approximately 95 percent of all of the

water in your pool being filtered once

every 24 hours if you filter your pool

on a very lean schedule or perhaps you

have a minimally effective filtration

system then you might not be filtering

your water enough and every last thing

that you don't filter out of your water

now the chemicals in your water need to

try to deal with and so you could end up

using a lot more stuff like chlorine or

you have trouble holding the chlorine

level in your water and if I had

chronically green water I would

definitely want to take a look at my

filtration schedule and try to come up

with some sort of estimation as to how

much I'm filtering the water versus how

much I should to meet that three times

the volume of your pool turnover that

you should be getting

for your pool and in total these are the

things that I would do if I was dealing

with green water and trying to find the

source for it is just start by looking

at your chlorine you need to have it if

you don't have it there's your answer

right there if you do have it then look

at these other parameters like the pH of

the water the cyanuric acid level and

whether you have phosphates in your

water and probably you'll find the

reason why your pool water turned green

somewhere in here if you found this

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swimming pool Steve calm