No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

JS AZ

New member
Sep 27, 2018
3
Phoenix, AZ
I have been trying to remove some stubborn spots (algae) on bottom of pool. Added 2lbs of YellowOut algae product, then shocked (7 bags Clorox Xtra Blue Pool and Spa) on Sunday (had low FC) and I topped off the chlorine tablets (4 pucks) and then 3 days later (last night) I added 4 bottles (116 oz) Clorox bleach (recent made dates) to raise chlorine ppm.

Have a pebble tec 22,000 gal pool and have barely risen levels of chlorine. The algae doesn't seem to get worse in said areas but definitely not gone or visibly better. I am so obsessed over this now.

Water clear, and here in AZ, we are getting good shade in morning and temperatures are leveling to high 90's (water temp is around 80-85 depending on time of day). Running pump 8 hours in the early morning to mid afternoon.

I am getting consistent - but low chlorine readings from K-1004 and from the pool store yesterday (uses LaMotte digital test) - this is their readings

FC .09 ppm
TC .19
CC .10
pH 7.1
Hardness 328
Alkalinity 57
CYA 73

I have cleaned out my filter canisters 2x over the past month and the pump filter (at the side of pool) and brush pool at least 2-4x a day. I am relatively new at taking over the maintenance of my pool but never ever seen our pool guy (former pool guy) ever using this much chlorine.

What options do I have?? I thought there may be a chance that I've added too much chlorine but the water is clear, the dark spots of algae are still present and accounted for.... and the pool store test is also suggesting that I add much more chlorine as well. Help?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,433
Laughlin, NV
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

Welcome to the forum! :handshake:

Sorry you are having issues. First, we do not typically provide chemistry guidance based on pool store tests. At the end of the day, you need to SLAM Process. To do that you need a proper test kit that includes a FAS-DPD test for FC/CC.

The YellowOut is ammonia based and thus requires large amounts of chlorine to remove that ammonia.

I suggest you add 2 gallons of plain, no scent, not splashless 6% bleach to your pool each evening until you get your test kit. Then post the results here and we can provide guidance.

I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.

- - - Updated - - -

Order a TF100 test kit
The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want.
I also have the SpeedStir. It makes testing much easier.
 

scdaren

Bronze Supporter
May 20, 2018
343
Clovis, CA
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

^ what he said.

Also, avoid that Clorox brand bleach, it has additives (ie Cloromax technology) that you do not want or need in your pool. Buy liquid chlorine at the big box hardware store or pool supply (usually it will be 10 or 12.5% sodium hypochlorite), or generic plain bleach.

- - - Updated - - -

^ what he said.

Also, avoid that Clorox brand bleach, it has additives (ie Cloromax technology) that you do not want or need in your pool. Buy liquid chlorine at the big box hardware store or pool supply (usually it will be 10 or 12.5% sodium hypochlorite), or generic plain bleach.
 

JS AZ

New member
Sep 27, 2018
3
Phoenix, AZ
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

I have the Taylor K-1004 test kit and I brought another sample to the pool store because I couldn't believe how much chlorine was being depleted. In the end - test readings were the same.
I went w/ Clorox regular bleach because the Cloraren and some other generic brand didn't state what % content it has. Anyway I am heading off to the big box store for more bleach and will find another generic or higher concentrate version. Thank you!!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,433
Laughlin, NV
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

The Taylor K1004 cannot test FC/CC to the level you need. You must, at a minimum, get a FAS-DPD test.

FAS/DPD Chlorine CC's test

You also need to be able to test CYA. Potentially multiple times.
 

JS AZ

New member
Sep 27, 2018
3
Phoenix, AZ
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

Thank you! So I just keep adding chlorine...thanks for the Clorox tip. I am a little surprised at how much chlorine demand the pool has. I realize that perhaps all that Clorox Xtra Blue over the past weeks may have caused me some metal staining. I have some elevated copper (0.3ppm) so as long as I keep adding liquid chlorine instead of anything else, I think I am heading in the right direction...ping me back if not though!!! Have a great day!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,433
Laughlin, NV
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

Ok -- with the knowledge of the high copper usage and testing at that level, you need to plan to soon drain the bulk of this water and replace with fresh. First you would want to get the stains off the shell and into solution. With copper that can be problematic.

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Pool School - Metals in the Water and Metal Stains
 

scdaren

Bronze Supporter
May 20, 2018
343
Clovis, CA
Re: No/low chlorine reading after repeated tests & high amts shock/liq bleach added??

One of the reasons you have gone through so much chlorine is the ammonia added from the YellowOut product.

One thing you really need to get familiar with is the relationship between chlorine and CYA. The higher your CYA level, the higher level of chlorine you need to maintain to have a properly sanitized pool. My guess is you are having these problems because your chlorine levels are not adequate for your CYA levels. This chart will tell you what your FC level needs to be for a given CYA: Pool School - Chlorine / CYA Chart.

Also, you really need to get a proper test kit like the TF-100 to test your CYA to begin with. Pool store CYA tests are notoriously inaccurate. If you are measuring anything more than like an 80, you need to do it using a dilution method described here: Pool School - CYA

We always round CYA up to the nearest 10, so assuming your pool store test is correct, your normal target chlorine level needs to be between 9 and 11 ppm. To conduct the SLAM process described above (which is the ultimate solution to your problem), you'll need to get the FC up to shock level of 31 ppm. Again, you'll need the right test kit to be able to even measure these FC levels.

You'll note these numbers are pretty high. For this reason, you really need to get your CYA under control, and the only way to do that is to drain and replace enough water to dilute it down.

CYA is found in most solid forms of chlorine (others have CH which you don't want either). So going forward stick to liquid chlorine or get a salt water chlorine generator to avoid high CYA levels.