Cannot maintain FC levels w/ BBB

[PoolDoc]

With CYA=100, FC = 8 - 12 ppm would be fine.

If you were in an arid region, and using a DE filter, you could probably go lower. But in Pennsylvania, you'd be risking algae if you did so.

[Watermom]

Please don't think I was 'fussing' at you ------ I wasn't. It's just hard to mix and match advice from multiple forums. I hope that we have been able to answer your questions.

Let us know how your overnight test goes tonight.

[Slachey]

Thanks PoolDoc.

Watermom,

No offense taken at all. As mentioned, this site and the replies to my issue have been a great experience so far. I am leaving again for the evening so I added 2 gallons of 8.25% bleach. My FC was down to 13.8 this evening (No CC) from the 18 I measured this morning.

I'll test when I get home tonight and again in the AM.

I hope this stabilizes soon!

Thanks again.

[Slachey]

So I added (2) gallons of 8.25% bleach at 6pm on 6/28 when the FC was at 13.8. I got home at 10pm and the FC was 18. I checked at 6am the next morning and it was at 17. I did not add anything all day yesterday and checked the FC at sundown last night (~ 8:15pm) and the FC was at 12. It lost 5 ppm of FC all day. I checked again this morning at 6am and it was at 10, so it lost 2 ppm overnight. I added (2) gallons this morning hoping to get it up to close to 20 again for the day.

The CC is reading 0, so I am a bit confused as to what I am to do next. The pool is taking at least (1) gallon per day to "maintain" FC level.

Any additional help would be appreciated.

[Watermom]

I don't think you are in 'maintenance' mode yet. I still think you are fighting something in the water.

At 6pm Saturday night you had 13.8. Adding 2 jugs (I assume they are the 121-oz. and not gallons) would have added 9ppm which would put you at 22.8. Four hours later at 10pm, you had already lost 4.8. Then, you lost another 1ppm overnight. So, you actually lost 5.8 from sundown to sunup which is the time period we look at. (When you lose chlorine in the evening when there is no sun on the pool, it is lost due to oxidizing something in the water. When you lose it during the day, part of the loss is to the sun.)

It appears that your chlorine loss is lessening so hopefully you are getting close. I know you are getting frustrated but hang in there. I have a feeling that you are nearing the end. Report back in the morning.

[Slachey]

Thanks Watermom.

I will keep plugging along. Unfortunately we are leaving town tomorrow night and not returning until Saturday morning. That will be 3 full days of sunlight without me monitoring. How high would you recommend that I take the FC into shock level to hopefully keep us out of trouble while we are gone?

[PoolDoc]

Typical usage would be 2 - 3 ppm per day. But it can be much higher with incipient (barely visible) algal growth.

There is a bit of green spotting on the liner so that could be it.

You have NOT reached chlorine levels that would reliably exterminate mustard algae. Typically, that requires levels equal to 30% of the CYA level, or more -- 30+ ppm in your cause -- PLUS brushing.

Chlorine consumption also goes up, somewhat, as the water temp rises.

And, there are any number of pool additives which will create a long term increase in chlorine consumption: any product from United Chemicals, most products specifically for mustard algae, most stain removers, and plus other products we haven't specifically identified yet. Have you used any of those?

Anyhow, if you would, fill out these two forms, so we can be more confident we're not overlooking something:
http://pool9.net/pf-equip-form/
http://pool9.net/pf-hist-form/

[PoolDoc]

How high would you recommend that I take the FC into shock level to hopefully keep us out of trouble while we are gone?

30 ppm or higher.

[Slachey]

Thanks PoolDoc.

Are you saying that I should maintain 30+ ppm instead of 20 ppm that I have been using as shock level for the foreseeable future (i.e. until the overnight loss is 1ppm)?

I don't have the pump / filter info with me, so I will fill out the forms tomorrow.

[PoolDoc]

30 ppm prior to vacation, ESPECIALLY with possible hidden mustard algae.

Then, look at things when you get back. If there is hidden mustard algae, you'll probably have patches of it when you return.