Pool Chem levels

[Fugazi]

15k pool chlorine
PH 7.5
Calcium 325
Alkalinity 60
Cya 10-15 I filled the top of the test tube and i could barely see the dot
FC 8


Any reason to boost the cya levels?

I have been adding 3 cups chlorine a day and 1/2 cup ph down a week

 

[woodyp]

Is this an indoor or totally covered/shaded pool? I'd have it at least 30 CYA so you can more accurately tell what you have.

 

[domct203]

15k pool chlorine
PH 7.5
Calcium 325
Alkalinity 60
Cya 10-15 I filled the top of the test tube and i could barely see the dot
FC 8


Any reason to boost the cya levels?

I have been adding 3 cups chlorine a day and 1/2 cup ph down a week

Thats a pretty high FC level for next to nothing CYA.

Dom

 

[Fugazi]

Thats a pretty high FC level for next to nothing CYA.

Dom

Yes I was keeping it on the top end of normal to ward off algae.

I was going to bring it down to 5-6 since the cya level dropped from a previous level of 45.

- - - Updated - - -

Is this an indoor or totally covered/shaded pool? I'd have it at least 30 CYA so you can more accurately tell what you have.

It's an ourdoor pool that is shaded for half the day only until noon does the sun start to hit it.

 

[ozdiver]

Was their a 'life event' that occurred to drop the CYA?
Heavy rain and overflow, partial emptying of pool and refill?
It is unusual for the CYA to swing that amount.
Might want to retest that to confirm it before making other adjustment as the pool is acting like there is more CYA than the last test indicates.

 

[domct203]

Yes I was keeping it on the top end of normal to ward off algae.

I was going to bring it down to 5-6 since the cya level dropped from a previous level of 45.

Even 5-6ppm with no CYA is harsh. If this was my pool I'd bump the CYA to 30-

Is there visable algae in the pool?

How often do you check FC?

Dom

 

[Fugazi]

Was their a 'life event' that occurred to drop the CYA?
Heavy rain and overflow, partial emptying of pool and refill?
It is unusual for the CYA to swing that amount.
Might want to retest that to confirm it before making other adjustment as the pool is acting like there is more CYA than the last test indicates.

We had two days of flooding rain and I had to drain my pool as it was almost overflowing.

- - - Updated - - -

Even 5-6ppm with no CYA is harsh. If this was my pool I'd bump the CYA to 30-


Is there visable algae in the pool?

How often do you check FC?

Dom

Is there any reason to bump the cya tho? What reasoning is it to be high versus zero?
There is some black spots what I assume is black algae other than that it's clear water.
I check FC every weekend and and chlorine every day.

 

[ozdiver]

Ok, so that was the life event.

Zero CYA means there is nothing 'holding' the FC in the water when the sun is beating on your pool.
Up north they can stay on the low end of the CYA range but down south where we are, staying closer to the top prevents the 5-7 ppm FC drops during a sunny day.
Even with 30 CYA my pool can lose 5 ppm on a sunny day.
When I raised it to 50, I lose maybe 2ppm.

So having enough CYA in your pool to prevent you falling below min FC during a day is a must.
Any time you are below min FC, algae IS growing.
Initially this will be noticed in a >0.5 CC
That shows your FC is being consumed by something; either bather load or algae.

 

[domct203]

Not only does the CYA protect FC from UV, it also buffers the FC so it is not as harsh on your skin, hair, swimsuit, liner etc.

You should either drop your FC levels to maintain 2-3ppm (which is hard to maintain in open sun) or raise your CYA.

Why the hesitation to raise CYA?

Dom