How much Bleach is it normal to add per day?

[JDFester]

Pool looks great; crystal clear, passes OCLT, CC is 0.2ppm or less, no known issues (other than hardness is low, but I'm told that doesn't matter on FG pools?)

Due to a somewhat ongoing issue with suspected Mustard Algae, I am trying to keep above the Mustard Minimum Chlorine level. (Pool is fiberglass, but old, and gel coat is wearing away leaving some rough surfaces, so I am continuing to brush aggressively daily, etc.)

My test results are:
FC=5.0 (raise to 8.0 in the mornings before leaving for work, reduces back to 5 and stabilizes by sundown)
CC=0.0
pH=7.4
TA=110
CH=80
CYA</=20

Intentionally keeping the CYA on the low side; have a couple of week-long trips coming up where I want to be able to leave tabs floating, and trying to keep the level low for effectiveness against any remaining Mustard.

This is requiring a half bottle of 10% liquid chlorine per day; I am just wondering how this compares with the experience of others?

Thank you!

 

[mknauss]

Most pools as we dive into the heart of summer will use 3-4 ppm of FC per day. With your low CYA you will lose more.

I would suggest getting your CYA to 40. That still leaves you room for using pucks and keep your CYA below 60. And you have a sand filter so a backwash will replace some water too.

Take care.

 

[borjis]

CH can and often does matter in fiberglass pools, at least that's what several people have posted when discussing it.

Is your pool exposed to sunlight? I can tell you with a cya that low, it will definitely consume it much faster.

I started with a fresh fill 2 years ago and tried cya at 30 and it just consumed too much fc.
So I tried 50 and that along with a blue bubble cover maintains a pretty good lasting fc level.

 

[mknauss]

In older fiberglass pools were a calcium based gel coat was used CH does matter. I am not sure how 'old' the pool needs to be for it to matter.

 

[Texas Splash]

Since you asked about comparisons, our pools are both FB and about the same size. Very, very hot all of a sudden here in south TX. Water temps creeping up into the high 80s already. My CYA is at about 50 right now, and I go through 2-3 ppm a day. I typically add about 1/2 gallon of 8.25% strength each evening. Sounds like you are doing well for such a low CYA. But I agree with Marty, watch that low CYA. One day the sun may steal more FC than you predicted and end-up on the low end about to battle and algae bloom. Good to hear you're planning ahead for your trip.

 

[Mickey Moose]

From May 1, 2017 - Sept 1, 2017 - basically Summer - my average daily Chlorine loss was 3.1 with a CYA of ~40. That's for a full-sun pool in Dallas, TX with, generally, one pool party a week at a minimum. Rounding to 3, I'll need to add 115 oz of 8.25% bleach to get to my goal of 6 in 26k gallons.