Ammonia pH and FC fun

[reven]

Hi all,
I’ve been a member for a short while now. My first dilemma was solved with my first SLAM. I now have a similar issue but it’s not working out so well thus far.

Numbers first:
FC: 2.2
CC: .5
pH: 7.2
TA: 120
CYA: 0

This started after my water turned very cloudy after some heavy rains. At that time my pH was 7.6 so I wasn’t worried about rain having affected my water. I have an autocover on almost all the time. I kept adding bleach to bring up my very low FC (can never get it above 2 usually). I was about to throw some CYA in but read that it may have been eaten up by ammonia (what else could have?). I have not drained.
So following forum posts, I started to SLAM to remove the ammonia before adding CYA. Been slamming for 3 days now yet my FC keeps dropping and CC more or less hovers at the same.
But my pH has been dropping, which I don’t understand. I have my jets pointed up making nice little fountains and a small suction leak I thought might actually be to my advantage in trying to aerate (closest jet to the pump blows lots of bubbles).
So long-winded post…I’m trying to figure out what I’m doing wrong. I’m adding 10-20 gallons of liquid chlorine daily. I’ve not added borax yet or CYA in case of ammonia. My FC keeps dropping even though CC is relatively low. I’ve been vacuuming and cleaning the skimmer daily. Robot is running 4+ hrs daily. I cleaned my filter last night too. The water is pretty clean other than cloudy. Only thing I can think is having the autocover on hurting? If so, how can I keep slamming when the sun is hitting it without any CYA? Thanks in advance to anyone with enough patience to read all this .

 

[ajw22]

Let’s back up a little. If you add 10 ppm of chlorine to your water and test it after 30 minutes what is your FC?

The process of killing ammonia with chlorine lowers your pH.

Leave your cover open.

Ammonia - Further Reading

www.troublefreepool.com

 

[andrewjstrominger]

I am working through ammonia troubles just like what you're describing: Add chlorine to SLAM level and 30 minutes later almost nothing. My CYA was also 0. Bacteria eats the CYA and ammonia is the byproduct. It took LOTS of chlorine to get it under control. I was seeing FC of 0.5-1 and CC in the 20s, yes 20s.

Here's my thread if you want more information: Featured - Really high ammonia

As ajw22 said, my pH dropped a lot as I started to kill the ammonia, so watch out for that.

I bought this ammonia tester to confirm it was my problem: API® Aquarium Ammonia Test Kit | fish Water Quality Testers | PetSmart

This is what it took to defeat the ammonia:

Update (all 12.5% liquid chlorine):
9:10pm 3 gallons
9:22pm 3 gallons
9:38pm 3 gallons
9:53pm 3 gallons
10:05pm 3 gallons
10:25pm - Finally got 5 FC and 2 CC reading - added 3 gallons
10:50pm -14 FC and 2 CC -Didn't add any since this is still above my SLAM level. This was a loss of 47% I will wait another ~30 minutes and check the levels again.

 

[JamesW]

Oxidizing ammonia (NH3/NH4+) creates acid by releasing hydrogen.

More than 95% of ammonia is in the form of the ammonium ion (NH₄⁺)

The chlorine oxidizes the nitrogen and the 4 hydrogen ions are released.

So, even though liquid chlorine has a high pH, the 4 hydrogen ions are a lot of acid.

Hydrochloric acid is hydrogen ions and chloride ions in water. So, it's basically the equivalent to adding acid.

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

When adding 12.5% sodium hypochlorite (liquid chlorine) to a pool to oxidize ammonia, every gallon of liquid chlorine will create the equivalent of 15 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 23 ppm or the equivalent of adding 150 ounces of full strength 31.45% muriatic acid.

Every 8.53 gallons of 12.5% liquid chlorine is equivalent to about 1 gallon of 31.45% acid.

 

[reven]

Good information everybody. @ajw22 i just added 2 gal, left the cover off 30 min and am now at 7.2 FC and 0.2 CC. I added another 64oz per pool math and will check again in 30 min. Off to HD to buy a ton more chlorine! I’ve dumped over 30 gal so far this slam. Maybe I’m just not checking often enough, 2-3x daily?

 

[ajw22]

Good information everybody. @ajw22 i just added 2 gal, left the cover off 30 min and am now at 7.2 FC and 0.2 CC. I added another 64oz per pool math and will check again in 30 min. Off to HD to buy a ton more chlorine! I’ve dumped over 30 gal so far this slam. Maybe I’m just not checking often enough, 2-3x daily?

You are past your ammonia problem if you had 7.2 FC after 30 minutes.

Add 30 ppm of CYA and follow the SLAM Process with a FC of 12.

 

[andrewjstrominger]

Yes, I agree with @ajw22. If you had ammonia you are past it.

 

[reven]

I’m not doubting your analysis but I’d like to understand how to determine that without an ammonia test.

Also, can someone explain what having the cover open helps with? Is it just being able to off-gas?

 

[JamesW]

Holding FC, no CC and no pH/TA drop are all indicators of ammonia being gone.

No cover allows gasses to offgas and it allows the UV from the sun to help the process along.

Gasses can include nitrogen, nitrogen trichloride, oxygen and others.

 

[reven]

I’m not fully on board yet. Just tested again and FC is 4.5, CC is 0.5. It seems the FC is constantly dropping, I just keep adding more to bring it back up. And the CC hasn’t budged much from 0.5.

 

[mknauss]

Just tested again and FC is 4.5, CC is 0.5.

With 0 CYA, FC will drop by about half in one hour with the sun on the pool surface.

 

[ajw22]

I’m not fully on board yet. Just tested again and FC is 4.5, CC is 0.5. It seems the FC is constantly dropping, I just keep adding more to bring it back up. And the CC hasn’t budged much from 0.5.

At this point you are fighting algae, not ammonia.

 

[JamesW]

Even if ammonia is still present, you can add CYA because the bacteria that breaks down the CYA should be gone.

The ammonia has no adverse effect on the CYA.

 

[reven]

Then wouldn’t I be better off covering the pool? Also no sun today, maybe it still hits through clouds? It’s been raining on and off. I’m covering it when it pours but in between opening to offgas.

 

[JamesW]

The UV helps the process. So, it's better to leave it uncovered.

Adding CYA is fine once you are sure that the bacteria responsible for eating the CYA is gone.

Bacteria is relatively easy for chlorine to kill. So, it's unlikely that any of the bacteria are still in the pool in enough concentration to do any harm.

 

[reven]

Okay thanks for explaining. I’ll work on the CYA now and finish SLAMing.

Should I pay attention to pH or give it time to correct after SLAM and via aeration?

 

[JamesW]

The pH should be fine for now.

The TA will keep the pH from going too low.

 

[reven]

Okay. Thank you all for the guidance.