How to lower combined clorine level?

[maintainpool]

Did you remove the pucks as Dom suggested? They are very acidic AND can help the ammonia survive in spite of your efforts.

The 3 inch Trichlor pucks are still in the chlorine feeder (5 pucks in total), however we turned the feeder dial to zero (off).

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what would you suggest adding to raise TA? our TA has been running high since opening the pool (around 130), but it seems each day the TA is dropping as we add more chlorine.

Oxidizing ammonia is acidic because ammonia contains 4 hydrogen ions, which are released when the chlorine oxidizes the nitrogen.

2NH₄⁺ + 3OCl^- --> N₂ + 3H₂O + 2H⁺ +3Cl^-

Raise the TA by about 10 ppm and then continue SLAM.

 

[JamesW]

Turn the feeder to full but do not open. The pucks are still dissolving and need to have water flowing through the feeder.

Add 10 lbs baking soda. Brush the pool to mix and then continue SLAM.

 

[jblizzle]

If the TA is still above 60ppm, I would not worry about raising it.

Seems you may not recall what is in Pool School:
Recommended Pool Chemicals

 

[JamesW]

It's probably not urgent to raise the TA. The pH should not get dangerously low.The pH will recover.

However, the pH and TA will continue to fall as the ammonia is oxidized, as the tabs dissolve and when the cyanuric acid is eventually added.

So, I think that the TA could be raised a little, or not. Either way should be fine.

What is the current TA?

 

[maintainpool]

Turn the feeder to full but do not open. The pucks are still dissolving and need to have water flowing through the feeder.

Add 10 lbs baking soda. Brush the pool to mix and then continue SLAM.

why put the feeder on full? thought we did NOT want any Trichlor CYA getting into the water right now?

 

[kellyfair]

I don’t understand the lingo of the tab feeder because I don’t have one, but yes, from what I understand, you do not want to add CYA until ammonia is gone.

 

[JamesW]

Once the bacteria is gone, there is no reason to avoid CYA. Bacteria break down CYA. But, chlorine quickly kills the bacteria. You don't want to add CYA while there is still bacteria in the water. All bacteria should be gone by now.

The tabs are wet and will continue to dissolve. So, the concentration in the feeder will get very high and will begin to damage the feeder. It's better to keep the water moving.

Don't open the feeder because there will be chlorine gas built up which is dangerous if you breathe it in.

 

[kellyfair]

James, the ammonia isn’t gone yet. What is the safest way to deal with the tab feeder until the ammonia is gone?

 

[JamesW]

All of the ammonia does not need to be gone before adding CYA. Only the bacteria that creates the ammonia by eating CYA has to be gone.

 

[borjis]

Just to confirm your chlorine testing, you are doing the 10 ML water sample, correct?

 

[kellyfair]

All of the ammonia does not need to be gone before adding CYA. Only the bacteria that creates the ammonia by eating CYA has to be gone.

Ah! How do you know when bacteria is gone?

 

[jblizzle]

Ah! How do you know when bacteria is gone?

Hard to be sure, so safest to assume when the CC is gone

 

[JamesW]

Most bacteria get killed pretty fast by chlorine. Based on the chlorine levels and the amount of time, I think that it's safe to conclude that the bacteria is gone.

It probably does not hurt to wait until all ammonia is gone to add CYA. But, in this case, I think that getting water flow on the tabs is the better course of action. You can leave the feeder off but, you don't want to leave it off for too long as the pH will get very low in the feeder while the chlorine gets very high. This can damage the feeder. You could remove the tabs but opening the feeder can release chlorine gasses. So, be super careful if opening the feeder. Remove the lid and walk away to let it air out. Do not look in the feeder right away or breathe in near the feeder.

 

[kellyfair]

Check in after you do this... so we won’t worry about you!

 

[maintainpool]

the feeder has been turned to the 'off' position for about 1.5 days now, how long before it can damage the feeder?

 

[JamesW]

Usually about 12 to 24 hours before the concentration begins to get super high and then the damage happens over time. I would probably open the valve to get some water flowing through there.

 

[maintainpool]

Just turned puck feeder back on full

Tested water with TF100 and also pool store.

TA is 80, pool store is 56
PH is 6.8, pool store is 6.9
CYA from pool store is 26
CC is 4.5 at both
FC is 1, pool store is 0.4
Total hardness is 196 at pool store
TDS is 1075 at pool store
Saturation index is Low at pool store

Pool store said to raise TA and PH before adding more chlorine.
Their recommended TA is 125 - 150 which is much higher than Pool Math recommendation. Not sure why.

 

[kellyfair]

Gotta bump that FC back up. According to what Jason says, CC isn’t gone so bacteria may not be gone either. So, just have to keep adding and testing FC until it starts to hold.

 

[JamesW]

Just keep adding the chlorine, it will eventually remove all ammonia.

 

[JamesW]

PH also dropped from 7.2 to 6.8. Does adding liquid chlorine drop PH and Alkalinity?

When adding 12.5% sodium hypochlorite (liquid chlorine) to a pool to oxidize ammonia, every gallon of liquid chlorine will create the equivalent of 14 ounces of 31.45% hydrochloric acid.

10 gallons of 12.5% liquid chlorine added to 25,000 gallons of pool water with ammonia will lower the TA by about 22 ppm or the equivalent of adding 140 ounces of full strength 31.45% muriatic acid.

Every 9 gallons of 12.5% liquid chlorine is equivalent to about 1 gallon of 31.45% acid.

(5) 7 ounce tabs will lower the TA by about 6.7 ppm from the acidity of the tabs plus another 4.2 ppm from oxidizing ammonia for a total of about 11 ppm.

Assuming another 10 gallons of liquid chlorine and the 5 tabs, the TA could drop another 33 ppm.

How is the water looking, is it still green and cloudy?