Help! CYA 70 to 10, CC 2!

[2thdoc1]

So I had everything perfect a couple weeks ago with my pool. CYA was 70, FC was 7, CC 0, pH 7.6, total alkalinity 90 (mine always runs a little high). Due to crappy weather and being out of town, I haven’t tested again until today. I run a SWG so chlorine usually maintains just fine. Today I notice pool looks cloudy. I tested and FC was 0, CC 2(!) and CYA was 10 or less?? PH was also 7! Any idea what’s going on? Where should I start? Increase CYA? SLAM??

 

[Texas Splash]

Any chance you might have a leak? A large CYA drop like that in one week is very odd unless you were half asleep during the CYA test. Ha.

 

[2thdoc1]

I do have a small leak under my pump - that was on my agenda to repair. That being said it’s not gushing water by any means, and my water levels are stable. Could that really drop it down that quickly?

 

[Donldson]

Add 10 ppm worth of chlorine, circulate 15 minutes and retest your FC and CC. Let us know what you get.

 

[2thdoc1]

Added 2 gallons of liquid chlorine (10%) 1 hour ago which should have gotten pool up to SLAM level of 12. Just tested and chlorine is at 1.0 and CC went up to 3.6?? What is going on? Should I keep adding chlorine? I have 6 more gallons but that’s not going to get me to where I need to be!

 

[PoolStored]

Added 2 gallons of liquid chlorine (10%) 1 hour ago which should have gotten pool up to SLAM level of 12. Just tested and chlorine is at 1.0 and CC went up to 3.6?? What is going on? Should I keep adding chlorine? I have 6 more gallons but that’s not going to get me to where I need to be!

Ammonia. It consumes CYA.

Ammonia - Further Reading

www.troublefreepool.com

 

[Donldson]

Yep, your FC likely dropped to zero and bacteria found its way in to the water. It ate the CYA and excreted ammonia.

Follow the instructions in the article above to rid it. Takes a lot of chlorine, unfortunately, but there's no other way to rid the pool of it.

 

[2thdoc1]

Well Crud- that’s a new one. Just added another 2 gallons and will check in 30 minutes. Could this be caused by lawn fertilization?? I know my lawn service came last week but I’m not sure what they put down. We also are surrounded by farms. It could just be from the chlorine drop I guess.
A couple more questions-
Should I add borax to raise the very low pH or wait for chlorine to stabilize? TA is high at 110.
Should I run my SWG to add additional chlorine at the same time or just shut it off?
Thanks!

 

[PoolStored]

Should I add borax to raise the very low pH or wait for chlorine to stabilize? TA is high at 110.

If your pH starts with a 7, leave it alone.

Should I run my SWG to add additional chlorine at the same time or just shut it off?

Shut it off.

 

[mknauss]

Many fertilizers have ammonium in them. It could have easily dropped your FC to zero.

 

[2thdoc1]

Added 2 gallons and FC was 1.2 and CC jumped to 4.4. Obviously still reactive. I backwashed to just above skimmer and am adding water to offset a bit, then added another 2 gallons LC. Will continue a couple more times tonight then will continue tomorrow when I can get more bleach. May add a bit of borax as pH is probably 6.6-6.8 (below the lowest 7.2 color on test kit). I’ll update when things start to clear!

 

[JamesW]

Oxidizing ammonia creates acid by releasing hydrogen.

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

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.

 

[2thdoc1]

Thanks for all the input! Finally at 11 pm after adding 2 gallons every 30 mins finally got an FC of 16 and CC down to 1. Going to see what loss looks like tomorrow morning and go from there with SLAM until clear.

 

[JamesW]

What is happening with the pH and TA?

 

[2thdoc1]

Continuing to SLAM after initial ammonia issue (FC and CYA went to 0 and pH below 6.8). Holding chlorine now since Saturday evening and added some CYA (now at 50). Yesterday evening I could start to see the bottom of deep end (8 feet). This morning, water is much clearer- can clearly see bottom, but it is still very green. My hope is this is still algae that just needs to filter through? My concern is I was running the heater for a day without realizing pH was so low/ammonia issue and I may now have copper? Does this look like copper or should I just see if color clears up over the next day or two? I don’t have a copper test kit anymore but can get one if it’s warranted.
Currently:
FC 20.5
CC 0.5
pH 7.5 (probably not accurate with high FC but wanted to check it)
CYA 50

 

[PoolStored]

I doubt it is copper. Looks like algae to me. Slam on!

 

[2thdoc1]

Thanks! Getting paranoid lol- this is only the second time I’ve had to SLAM because TFP methods keep everything looking awesome! Determined initial issue was due to lawn/farm fertilizers getting into pool. Going to really have to watch that next spring.

 

[JamesW]

Probably algae.

Maybe some iron.

 

[2thdoc1]

So pool is now looking clear but still very green. Still have FC at SLAM levels and will do OCLT tonight to check. CC is less than 0.5. I’m really thinking there may be some copper and/or iron that appeared due to low pH through the heater. Going to see if I can test for it to be sure. In the mean time, I do have some Jack’s Purple Stuff laying around. If I add it and the color clears, can I assume it is metals? Is it ok to add with SLAM chlorine levels? Should I just hold off and give it a few more days? My concern is if chlorine goes back to “normal” levels I’ll end up with staining. Pic is of 8’ deep end. Can clearly see bottom and drains.