FC measurement

[joemkraus]

FC=6, PH=7.6, CYA=40, CC=0
I have been trying to keep my pool FC at 6 each morning and the following morning it has gone down to about 2.0-2.5 powder test, so I add about 1 gallon of LC. Getting expensive, but OK if that is what I have to do. However, this morning when I measure again the FC=2 with powder, I tried the drop test and it looked more like 5 to me, definitely more than 3. Which reading is more accurate? I always assumed the powder?

 

[JoyfulNoise]

Are you comparing the FAS-DPD (powder and titrating drops), which is the pink colored test, to OTO, which is the yellow color test?

 

[joemkraus]

yes

 

[JoyfulNoise]

The pink DPD is much more accurate. OTO drops are notoriously off and no longer even used by commercial pools for reporting chlorine levels. I once tested them side by side - my FAS-DPD test said 2/2.5 and the OTO was a bright orange (above 5).

Your FC was 2ppm. Are you measuring your CCs as well? Are they <0.5ppm ?

 

[joemkraus]

thanks yes, CC=0
guess was hoping drops test (OTO ) more accurate, therefore having to use less LC

 

[JoyfulNoise]

Manual chlorination means adding chlorine everyday. 2-4ppm loss is normal in warm climates with high sun. Most people get pretty frustrated with “jug-dumping” after a short time. Most either convert to an SWG or invest in a Stenner liquid chlorine injection pump.

 

[joemkraus]

OK, thanks so much confirming that my FC loss of 4 is not out of the question (yes, warm sunny California weather here and pool is in sun most all day). I don't mind the jug dumping just the expense, but don't really want to complicate the process with SWG, but will look into the chlorine injector you mentioned.

 

[PoolNewb2020]

I would be a little concerned of the FC dropping to 2 during the day and staying at that level overnight. When you add it back up in the morning, it starts to burn off right away, so the higher level of FC is not in there for long.

I do my measurnments and add FC in the evening. My rationale is that this way a higher level of chlorine is present in the water for a longer period of time because at night FC doesn't burn off if the chemistry is balanced.

Not sure if it makes any difference though.

 

[JW1]

I would be a little concerned of the FC dropping to 2 during the day and staying at that level overnight. When you add it back up in the morning, it starts to burn off right away, so the higher level of FC is not in there for long.

I do my measurnments and add FC in the evening. My rationale is that this way a higher level of chlorine is present in the water for a longer period of time because at night FC doesn't burn off if the chemistry is balanced.

Not sure if it makes any difference though.

Do you add before or after the daily sunset?

 

[PoolNewb2020]

I do it before sunset because the weather is so nice and I like to do it outside, so I need some sunlight to see the color change. But by this time my pool is in the shade.

 

[joemkraus]

I always did in the morning, as my pump quits around 6pm for the solar heating and then the LC would not circulate, but guess I could do around 4pm

 

[joemkraus]

OK, I have switched to evening checking and LQ dumping, thanks for the tip, yea, my FC stays pretty high all nite, so great suggestion!

 

[JoeSelf]

Look for refillable jugs from a pool store. Larger size containers and stronger concentration.

 

[JW1]

This is the first summer with my pool and I have been adding after sunset. Allows me to recheck FC later that night and/or in the morning if need be.