FC tested 27...Questions

[NjPool84]

I've owned pools for about 9 years. Pretty avid and knowledgeable owner having helped others on forums myself. A bit stumped here...

Using taylor test kit, tested FC today and it registered 27. No one has been in the pool in about 2-3 weeks... Its end of season here in NJ. I'm struggling to understand how it could have gotten so high.

The chlorinator was left on a 5 or 6 (a pool tech was out fixing the heater and had to move things... Im thinking he adjusted the dial because I usually leave it at a 2. I did dump about 1 jug of liquid chlorine in about a week or so ago. No swimmers until yesterday (myself...I cant imagine what harm might come of this.. ). I did just rebuild my backyard this week with topsoil.seed,fertilizer. When I ran the pool bot today, it did pick up a bit of fertilizer and seed (or so it looked like). Scotts new lawn starter food. PH was also low, around 7... TA test returned yellow and wouldnt go red. I was able to quickly bump up the PH to a 7.2

Im thinking two scenarios:
1. Simplest: No swimmers for 2-3 weeks, chlorinator left on a 5 plus a helping of liquid chlorine...
2. Fertilzer tanked TA/PH and somehow messed with chlorine jacking that up.

Or a combination of both.

I've been draining a few inches and replacing a few inches with tap water all day. I then decided to just drain the pool down to the shallow end floor so I just took out enough water below the skimmers. Tomorrow I plan to go the rest of the way and replace with tap water. Basically replacing half the water in the pool.
Thoughts?

 

[proavia]

What test kit are you using?
Post a full set of current test results from one of the recommended test kits - Test Kits Compared

FC
CC
pH
TA
CH
CYA
Water temperature

Likely the tab chlorinator being left on 5 and no swimmers for a few weeks, along with the change in sun angle and lower temperatures, have lead to the increase in FC levels.
Usually, when chlorine is high, you can just let the sun burn off the excess.

If draining to exchange water, don't drain below about 12" to 18" in the shallow end to keep the liner from shifting.

 

[NjPool84]

What test kit are you using?
Post a full set of current test results from one of the recommended test kits - Test Kits Compared

FC
CC
pH
TA
CH
CYA
Water temperature

Likely the tab chlorinator being left on 5 and no swimmers for a few weeks, along with the change in sun angle and lower temperatures, have lead to the increase in FC levels.
Usually, when chlorine is high, you can just let the sun burn off the excess.

If draining to exchange water, don't drain below about 12" to 18" in the shallow end to keep the liner from shifting.

Hi, thanks for the reply. Mentioned in the original post, its a taylor test kit.

FC: 27
CC: Unknown (usually dont test)
pH: 7.2 after PH Up
TA: Unable to test as the sample turned yellow instead of expected red.
CH: Unknown
CYA: Unknown
Water Temp: 86

I'll try the partial drain and refill (city water is one of the only things in NJ that is relatively cheap). Was wondering if maybe excess fertilizer from when I was working in the yard messed with chems maybe giving false FC readings. I had some extra Chem-Out which has been great in the past in lowering FC but after about 4 doses, no change so I decided to just partial drain and refill.

Ill also add that Im mainly concerned about the high FC low PH water flowing through the brand new heater we had put in this year. The first heater something broke and the pool company replaced it after several visits to try to fix the problem. ...at no cost. Amazing. I dont want the insides to corrode under this extremely toxic environment

 

[Bperry]

Hi, thanks for the reply. Mentioned in the original post, its a taylor test kit.

FC: 27
CC: Unknown (usually dont test)
pH: 7.2 after PH Up
TA: Unable to test as the sample turned yellow instead of expected red.
CH: Unknown
CYA: Unknown
Water Temp: 86

I'll try the partial drain and refill (city water is one of the only things in NJ that is relatively cheap). Was wondering if maybe excess fertilizer from when I was working in the yard messed with chems maybe giving false FC readings. I had some extra Chem-Out which has been great in the past in lowering FC but after about 4 doses, no change so I decided to just partial drain and refill.

Ill also add that Im mainly concerned about the high FC low PH water flowing through the brand new heater we had put in this year. The first heater something broke and the pool company replaced it after several visits to try to fix the problem. ...at no cost. Amazing. I dont want the insides to corrode under this extremely toxic environment

It’s entirely possible a FC of 27 is just fine but depends on what your CYA test is. If it’s super high then it’s ok, but you’ll want to lower the CYA over time.

 

[proavia]

Mentioned in the original post, its a taylor test kit.

Which 'taylor' test kit. They make many of them.
Is it a Taylor K-2006C?
Add your test kit to your signature.

How old are the reagents?

Why is the CH and CYA unknown?
You need to test for those as well.

 

[Newdude]

I'm struggling to understand how it could have gotten so high

UV demand falls off a cliff for us in September. You've been adding your regular season amount of FC and picking up several FC per day.

The season more or less follows a pattern like a bell curve and you need to adjust your doses according to the recent loss.



Each tab you use adds about 2 CYA for you and It's likely pretty high.

 

[jimbethesda]

Without knowing your CYA level it’s impossible to know what chlorine level you should be at.