Chlorine monster eating all my chlorine....

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M

mr_gunite

0
Jun 23, 2014
66
New, England
Pool Size
28000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
So I yanked the cover off of my pool last Saturday (05/09/15) and got all of the holes unplugged, filled the water to skimmer level, and got the equipment running. Checked the levels using the TF Testkit, and got a lot of expected numbers, including 0 FC. I dumped about 3 jugs (121 fl oz each) of 8.25% Clorox bleach in the deep end and let it mix for a couple of hours. almost immediately after adding bleach, the water turned neon green, kind of as expected since my well water has high-ish levels of manganese and iron in it. I used a metal sequestrant and continued to run the filter.

I later tested and got the following numbers.

FC = 9
CC = 0.5
TC = 9.5
TA = 140
pH = 8.5+ (very purple)
CH = ??? (did not test)
CYA = 35

I did another round of chlorine, TA, and pH tests about 3 hours later, and found the following.

FC = 5
CC = 0.5
TC = 5.5
TA = 140
pH = 8.5+ (very purple)

So added 3 more jugs of chlorine, and boosted FC to about 14.
That was at about 8pm, so that was my last test for the night.

I came back the next morning and tested.

FC = 14
CC = 0.5
TC = 14.5
TA = 140
pH = 8.5+ (very purple)

Absolutely zero overnight drop and very little chlorine drop on Sunday. I started working on lowering TA and pH and dumped in a gallon of Muriatic acid. However, I kept the chlorine level at SLAM level around 14 since no one was going to be using the pool, and I just wanted to be sure about clearing out any algae blooms. I used about 4 gallons of muriatic acid over the course of Sunday, but pH barely moved, but TA dropped nicely to 110.
Sunday to Monday overnight drop was zero again with an FC = 14 in the morning.

I went to work and left the pool for the day on Monday and came home to find the FC level had dropped to 2.5 during the day and chlorine seems to be hemorrhaging now. Monday was actually pretty cloudy, and temps never went above 70F.

I did a drop test last night and found I lost about 1.5 ppm overnight. FC went from 13ppm to 11.5ppm.
Test results this morning.

FC = 11.5
CC = 0.5
TC = 12
TA = 110
pH = 8.5+ (very purple)

Am I fighting an algae bloom, or is something else going on here? Could the combo of the metal sequestrant plus the muriatic acid be killing my chlorine?

Water color is currently crystal clear to the bottom of the deep end, with a small amount of dirt on the bottom. I've vacuumed the pool once and brushed twice since opening. Also, I backwashed maybe five times since opening.

I have a 26k gallon gunite plaster IGP with DE filter that uses 4.8 lbs DE. Not sure about pump name and HP. This is my second season as a pool owner. Water was crystal clear and algae free all first season.

Any help is much appreciated!
 
I noticed that I was basically always chasing my pH level all last season. I thought maybe this was normal for a plastered gunite pool. Seemed like I was adding about a gallon of muriatic acid per week, so having relatively high pH wasn't too much of a shock to me. However, the fact that my initial TA was at 140, I figured it made sense that pH was at least a little high.
 
Your pH is more than a little high, It needs to come down today if you can do it.

Pretty normal to lose some chlorine to invisible organics in the pool when you first open. I would suggest you keep you chlorine elevated (7-10 ppm) for another couple of days and then perform the OCLT test. I'll bet you pass that and will be on your way to another great swim season.

KEEP that pH down in the 7's!!
 
duraleigh said:
Your pH is more than a little high, It needs to come down today if you can do it.

Pretty normal to lose some chlorine to invisible organics in the pool when you first open. I would suggest you keep you chlorine elevated (7-10 ppm) for another couple of days and then perform the OCLT test. I'll bet you pass that and will be on your way to another great swim season.

KEEP that pH down in the 7's!!
Click to expand...

I just want to make sure....so adding muriatic acid to get the pH down won't disturb my efforts of keeping chlorine in the pool?

- - - Updated - - -

Richard320 said:
Check the pictures here: http://www.troublefreepool.com/threads/58834-Accurate-pH-test-during-shock-levels-with-R-007

I've never had to use sequestrant, so I can't help you there.
Click to expand...

Wow, thank you for those pics. I've never seen the left side of the Taylor test kit turn orange like that before. This is kind of why I felt like chasing pH at this point was a little useless, since I was able to get TA down to an acceptable level, I figured I'd wait on messing with pH until I got this FC problem figured out.
 
pooldv said:
I will go ahead and be the third or fourth person to tell you to get your PH down to 7.4 or so today.
Click to expand...

I respect your help, and thank you.

I'm now wondering how do I measure pH if my FC level is being kept between 10 - 14 ppm? The link in post #4 above shows that the Taylor Test kit will always read falsely high until the FC level comes down out of SLAM levels. I was assuming that I had ultra high pH upon opening the pool and measuring pH with high FC levels, but after dumping 4 gallons of Muriatic acid into the pool within 4 days, I'm not sure I want to mess with pH again until I'm done slamming.

I got my TA level down from 140 - 110, so I'm thinking my pH is probably actually in the 6.5 range right now, just based on my experience of chasing pH from last year.

Please let me know what I might do otherwise to measure pH correctly with SLAM level FC.
 
That is true, your PH will read artificially high with FC above 10. You have two readings above that show PH 8.5+ with FC below 10.

How are you following the SLAMing Your Pool process when one of the prerequisites is
- Check and adjust the PH to between 7.2 and 7.5. The PH test isn't reliable during SLAMing so make sure to take care of this before you start.

Why did you add 4 gallons of muriatic acid? Did you use PoolMath to calculate how much acid to use? According to PoolMath 4 gallons of MA in a 26k gallon pool will lower PH by 4.73 and lower TA by 77.

I think that you should allow your FC to drop to 9, test and adjust your PH as needed and resume the slam following theses instructions.
SLAMing Your Pool
 
Yes, I think you are right. In my mad rush to try and avoid an algae bloom after opening the pool, I skipped the step of adjusting pH first. I guess I thought I had SLAM memorized, but really didn't. I'll try this starting tomorrow. Thank you for the help.

Just to put this into perspective, I used 8 gallons of bleach today to keep FC level at 10 -14 ppm. The air temp was a max of 68F and the sky was overcast most of the day. Yet the water looks crystal clear still all the way to the bottom of the deep end. I'll check for any overnight drop tomorrow morning.
 

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Last CYA test was Saturday at 35ppm? Try testing CYA again to make sure it is still there. That is a lot of bleach, 26ppm! Good that the water is clear. I guess the "good" news is that it won't take long for FC to drop below 10 so you can get the PH adjusted and resume.
 
Even in mid-July and August last year, on sunny 95F degree days, I think I might have been using 0.5 - 1 gal of bleach per day.
That was my main reason for starting a thread. It just seems like I'm using a colossal amount of bleach, even for an algae bloom, and especially in clear water. Makes me wonder if I'm growing some sort of mutant little shop of horrors plant inside my filter. It looked ok in there before opening.

I'll check CYA again tonight and then start breaking down that pH over the next day or so.
 
There is an idea that has been developing that in certain conditions that CYA is converted to ammonia. It seems to be more common this spring. Ammonia will use up chlorine more rapidly than anything else. A CYA test could help confirm this theory. Also, your case could point high pH as a contributing factor. In any case, if you have ammonia you still need to get rid of it and chlorine or water drain are the only two options.
 
My other concern is that during opening this year, like so many other newbie pool owners it seems, I managed to get a few gallons of RV anti-freeze into the water. It was enough where I can still smell the fragrance of it. Unfortunately, because it was my first year closing a pool last year, I bought a brand called Super Tech anti-freeze from Walmart, and paid no attention whatsoever to the ingredients. It contains Di Potassium Phosphate, which I've read over the last several days is a no-no, and the last ingredient just says fragrance. That last ingredient is kind of comical since the side of the jug claims that this product is odorless.

Just a stab in the dark here, could this rv antifreeze be contributing to the massive amount of chlorine being eaten up? Could this anti-freeze make good plant food somehow, and contribute to an algae bloom?

The ingredients list is as follows:

Ethyl Alcohol
Propylene Glycol
Water
Colorant
Di Potassium Phosphate
Fragrance
 
Just to add, my CC levels have been 0 - 0.5 every time I've tested since Saturday.

Is there a direct way to test for large amounts of ammonia in the water or is the CC test indicative of the presence of ammonia?
 
mr_gunite said:
Just to add, my CC levels have been 0 - 0.5 every time I've tested since Saturday.

Is there a direct way to test for large amounts of ammonia in the water or is the CC test indicative of the presence of ammonia?
Click to expand...
Aquarium/Fish stores do sell ammonia test kits, but I do not think you have ammonia. If I read things correctly you are holding FC fairly well. On of the first things to look for in an ammonia situation is a FC level dropping quickly, like in 30 minutes to an hour going to 0.

I wolud just say keep hitting the SLAM hard.
 
tim5055 said:
Aquarium/Fish stores do sell ammonia test kits, but I do not think you have ammonia. If I read things correctly you are holding FC fairly well. On of the first things to look for in an ammonia situation is a FC level dropping quickly, like in 30 minutes to an hour going to 0.

I wolud just say keep hitting the SLAM hard.
Click to expand...

I'm dropping about 3ppm per hour during the day, and about 2ppm over the entire night.
 

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