My pool is eating chlorine

giulietta1

In The Industry
Mar 29, 2007
289
Knippa, Texas
This may be related to the stain removal and chelating treatments I used last week, but my chlorine is really not lasting well! Another possible chlorine eater was the plant matter blown into the pool by the storm. We had a powerful storm Friday night/Sat morn; there was hail, we had a tree knocked down, and there was debris all over the yard and blown onto the house.

Despite its enclosure, my pool had a share of debris; it's not a tight building. I expect an outdoor pool would have been a lot worse! It only took me about 45 minutes to clean up the leaves, etc.

Let me see. . . I don't have my logbook in front of me, but I did check the chlorine Friday night before the storm. I think I topped it up to 4.5. When I tested the chlorine Saturday it was almost gone--0.2 or less. I topped it up to 9 on Saturday night. Sunday morning FC was 7.4; Sunday evening it was 3.6!

I have been adding borax to the pool (along with acid to offset the pH rise), but that shouldn't affect the chlorine, should it? I've added a total of 3 boxes of borax (4lbs 12 oz each) and almost a gallon of muriatic acid.

Also have been running the solar heater.

This morning FC was around 2.8. Not much overnight loss, but I've been having so much Cl loss during the day, I added 2 qts bleach to increase the FC by 3.

Maybe it'll stop eating Cl; I'll see what the FC looks like tonight. Just wondered if anyone had any ideas what could have caused such a Cl demand. . .
 

waste

TFP Expert
LifeTime Supporter
Mar 29, 2007
4,160
Coastalish 'down easter'
I'd have to say that the initial cause is the load of organic material which ended up in the pool, you removed the large stuff in a timely manner and I'll assume you vcuumed. Have you backwashed the filter? It's possible that you have some 'stuff' in the filter that hasn't been killed yet (if you run your pump durring the day, that could explain why the cl holds better at night).

Another possiblity is that you have no cya (as it's usually not needed in an indoor pool), but are leaving the doors or windows open enough to allow direct sunlight to reach the water (glass blocks the uv rays that cause both sunburn and chlorine burn out).

Just a couple ideas, let us know how it works out!
 

giulietta1

In The Industry
Mar 29, 2007
289
Knippa, Texas
I thought of most of those things; no, no CYA b/c it's indoors. Since the pool is not getting enough UV to break down CC's it's a good bet it's not getting enough UV to break down the FC's either.

I use a Pool Buster so I don't vacuum thru the filter. Had a skimmer sock in place also, so I am reasonably sure that not *much* organic debris made it to the filter. The pump is running 24/7 on low (no timer). Maybe I should backwash. I hesitated to add any more water to the already-soaked ground, and I had backwashed just a couple of days ago.

However, as you pointed out, there was more chlorine loss during the day; that certainly does point to the sun's influence again! I will have to get more data. I think I am in danger of becoming a compulsive pool tester. . . :wink: