Is my pool supposed to use this much chlorine?

sassafras1232

Member
Sep 10, 2024
6
San Diego
I'm new to owning a pool, but it seems like I'm putting in a lot of liquid chlorine. The last few days I've been putting in half a gallon per day and it doesn't seem to be moving the needle on my FC levels. I think I might even be starting to see green growing on the walls! I also don't seem to be able to get my pH down. Do I really need to be adding $5-10 of chemicals per day?

The pool and spa combined are about 13,000 gallons. The pump runs ~40gpm for 8 hours per day. The filter cartridges have been cleaned recently but they're on their last legs as they're starting to fall apart. We don't have a cover but are going to get one in the next few days. There are small leaves that fall into it but I am emptying the skimmer and pump baskets every day. It has a SWG but it was disabled by the previous owners because they said it was not working. I don't have the budget to replace it right now.

Date9/179/189/199/239/249/25
Test Methodstripstripstripstripstripstrip
Free Chlorine.503000
Total Chlorine.513000
pH8.28.47.88.47.88.4
CYA1005050505050
Total Alkalinity808080808080
Calcium50010001000100010001000
Chlorine added64oz64oz64oz64oz128oz
Muriatic acid added32oz32oz32oz42oz42oz
 
Welcome to the forum!
You need a proper test kit. I suggest the TF-100/Pro or Taylor K2006C. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.

While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
 
Welcome to the forum!
You need a proper test kit. I suggest the TF-100/Pro or Taylor K2006C. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.

While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
I have the TF test kit. Every time I used it it agreed with the strips so I stopped bothering because it takes so much longer to do.

Based on the calculator app 5ppm is basically a gallon of chlorine. So you're saying that it's normal to go through a gallon per day? I guess I need to be stocking up on it...
 
Dump the strips, they are junk and erratic. It's normal for your size pool (mine is 11000 gallons) to use 1/3 - 1/2 gallon per day right now as the sun gets lower. Your FC is grossly low. As the water cools you will use less and less CL each day though you need to keep up on it and keep your FC in line with your CYA. There is a direct relationship between the two giving a recommended range for a given CYA level. Always aim for the high side of the FC range.
FC/CYA Levels
 
I couldn't find a date code on the bottles, but they're from a very busy Home Depot location. There's a lot of pool owners around here. So I don't think they'd be really old stock.
It could still be old, need to find the date to guarantee freshness.
Chlorine Date Codes
It's generally some form of YYDDD (example 24150 would be 150th day of 2024)

You have some visible algae so that will use more chlorine than normal. You can have algae without being able to see it as well so even if it appears to go away after a small chlorine dose, that doesn't mean it is completely gone. The overnight loss test and SLAM mentioned above are your likely next steps.
 
Ok so right now (about 3 hours after adding chlorine and acid) I'm seeing the following:

Color change blocks: 3ppm Chlorine, 7.8 pH

Drops:
9 ppm FC
.5 ppm Combined Chloramines
CYA 50-60 (I still have a hard time interpreting the viewing tube)

So based on the drops I am getting a good amount of FC from what I added this morning. I think that eliminates the "old chlorine" question.

I think I am just not interpreting the color block test correctly. I find it really hard to distinguish the different shades of yellow.
 
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The OTO drop based chlorine test is really only useful for saying "is there any chlorine or not." Otherwise, it's utterly worthless. I pitched that reagent in the trash after first use. FAS-DPD is accurate and repeatable.

An Overnight Chlorine Loss Test would be very wise.
I don't think that the overnight chlorine test would be useful since there are leaves falling in the pool. I know that there will be organic matter in it at any given time due to the leaves. Maybe after I get the cover on it that would make sense...
 
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