Can adding a lot of calcium chloride at once reduce FC??

[mgtfp]

I would think that CC would have tested higher from the earlier test given the strong chlorine smell. One would assume chloramines, no?

In Matt's theory, FC turns into chloride, not CC. Not sure how the leftover cyanides react down the line with chlorine.

With FC being depleted, one could get stuck with some chloramines, I imagine.

But I agree, chloramine smell should correlate with CC showing up, so it would be interesting to know if the smell was there after the calcium chloride addition, or only after chlorine has been reintroduced.

 

[pooldewd]

I would think that CC would have tested higher from the earlier test given the strong chlorine smell. One would assume chloramines, no? @pooldewd did you smell the chlorine smell during the second test?

I didn’t notice it during the last test, no.

As a side note, the need for acid has dropped dramatically since this started. I was using about 14oz or more daily (since the plaster was done mid April) to keep it in range and haven’t needed any since this started 3 days ago. Had to add soda ash for the first time ever per the Pool Math app. Could be nothing, but thought it was interesting.

Having gone through over 3 gallons of 12.5% bleach in the last 3-4 days hopefully this evens out soon lol.

 

[mgtfp]

Had to add soda ash for the first time ever per the Pool Math app. Could be nothing, but thought it was interesting.

When you say you "had to", how low was pH actually?

 

[pooldewd]

When you say you "had to", how low was pH actually?

7.4. App has my ideal range at 7.6 - 7.8. Maybe not the end of the world, but trying to commit to the process as much as possible . I’ve been out of that range before, just never towards the low end.

 

[Newdude]

7.4. App has my ideal range at 7.6 - 7.8.

Ok. Without using tabs, you're not adding acid regularly and your PH will always rise. You never need to raise it if it is a 7.X, it will get there on its own. Any 7 is equally OK.

'Ideally' at a high 7 PH, the Ph will rise slower, which why we recommend it. Oh the irony.

But.

If there was anything for you to foul up or misinterpret, you picked a good one. Well done there. Zero harm happened.

 

[mgtfp]

7.4. App has my ideal range at 7.6 - 7.8. Maybe not the end of the world, but trying to commit to the process as much as possible . I’ve been out of that range before, just never towards the low end.

Keep in mind that PoolMath is in the end just a calculator. It prefills the target field with the middle of the "ideal range", just to put a number there rather than leaving it empty. That doesn't always make perfect sense.

As Newdude explained, pH rises on it own (due to CO2 outgassing), so it will rise to the "ideal range" all on its own where the pH-rise will slow down - that's why we called it "ideal".

There's nothing wrong with lower pH, as long as it's got a 7 in front of the dot. Only disadvantage is that pH rises faster from there. Therefore you don't want to lower pH when it is in the ideal range, because it will just rise back up. But when it is below "ideal" there is no need to force it back up, it will do that on its own.

 

[pooldewd]

Just to follow up on this, I am now seeing a .5 PPM reading of CC...but also a drop in CYA (70 to 55). Don’t suppose these calcium contaminants could cause a CYA drop too? I cleaned bottles and re-ran the test twice, and I feel OK with my methods it’s a simple enough test.

 

[Bperry]

Just to follow up on this, I am now seeing a .5 PPM reading of CC...but also a drop in CYA (70 to 55). Don’t suppose these calcium contaminants could cause a CYA drop too? I cleaned bottles and re-ran the test twice, and I feel OK with my methods it’s a simple enough test.

I can make the CYA test even easier. Dont keep adding drops until the dot dissappears. Fill up the vial to the 30 mark and THEN check if the dot is visible. If it is, then fill to the 40 mark, if its still visible, fill to the 50 mark and so on. Once it dissappears, report that as your CYA. The chlorination levels are the same for numbers in between the “decade” value so dont spend time trying to figure out 55. Its either 50 or 60.

On top of that, the test has a variation of +\- 10ppm at least so dont spend time trying to figure out small numbers between the 10’s.

 

[panamax53]

They are suggesting I start a new thread, I will but want to add to this one here also to support the FACT that I had a massive unexpected drop in FC due to adding Calcium Chloride despite the fact pool math says there should be no affect. I am anal about testing my pool. Yesterday I added 13 lbs of Calcium Chloride that I had mixed into two 5 gallon containers the night before. I added them at 10 am tested FC afterwards and found it a bit low at 4.5. Added 144 oz of Chlorine Bleach. That takes my FC up about 5.1 ppm. The SWCG was set at 80%. With 12 hours runtime yesterday and 6 today that should have produced 18 x 0.2288 = 4.1 ppms FC for a total of 4.5 + 5.1 + 4.1 = 13.7 ppm
Figure an overnight loss of 1 to 1.5 and and a daily loss of 3. I should be around 9 to 9.7. Instead I am down to 2.5 ppm FC at 2 pm the following day! That is a 7 ppm of FC loss due to adding the Calcium Chloride.
My CYA level should be between 75 and 80 after last week's addition of dry stabilizer.
THere is no algae in my pool. It is clear and looks great.
I think this subject requires more investigation by the experts. A warning as to possible impact of FC loss might be added to the effects of adding calcium chloride in large quantities. Where that breakpoint of dramatic loss is needs to be determined.

 

[Newdude]

I think this subject requires more investigation by the experts.

They tried due to many members reports but weren't able to replicate the problem. The going theory is that fillers/additives in some brands bags kills FC. It's well documented on the forum, just not in Poolmath.

A warning as to possible impact of FC loss might be added to the effects of adding calcium chloride in large quantities

That's a great suggestion. Let's let @Leebo know to put it on the neverending to-do list.

 

[ajw22]

They are suggesting I start a new thread, I will but want to add to this one here also to support the FACT that I had a massive unexpected drop in FC due to adding Calcium Chloride despite the fact pool math says there should be no affect.

It is in the Wiki...

Calcium Hardness - Further Reading

www.troublefreepool.com

 

[panamax53]

I have been a vinyl pool owner for 3 years now, and each year I have tried to tackle a balancing issue. Last year I tackled CYA (I had near 0 and was losing FC rapidly during the day). I used a conditioner to increase CYA to about 50-60, and FC problem solved.

This year, I am tackling calcium hardness. CH has always tested at about 40ppm using my Taylor K-2006 kit. Yesterday, I broadcast about 25lbs of "Pool Mate Calcium Increase for Swimming Pools" (made by Robelle). It all dissolved very quickly, no cloudiness or white residue. Immediately prior, I tested FC at about 3.0 ppm.

Good news this morning is CH is testing at a much more reasonable 240 ppm. Bad news is FC is down to 0.6 ppm!!

I have an SWG (Pentair IC-40) that I generally run at about 40% capacity 24/7 during the summer (next year's project is getting off 24/7!). I checked CYA again this morning and it is around 60ppm, so that's not the culprit for the FC loss. I don't see any algae or organic growth. I jacked up the SWG to 70% output about 3 hours ago, and as of yet, no change in FC.

My question is: Can adding 25lbs of calcium chloride at once have a short term impact on FC?

Alternatively, could my SWG be going (I probably have over 10,000 hours on it and have never acid washed)?

Thanks!

Right. Another example that it does impact! Not sure why he added Calcium to a vinyl lined pool. Not required according to my understanding.

 

[pre]

Adding a data point for folks. We refilled our plaster pool about two months ago and I've slowly been rebalancing things.

CYA at ~30, FC of 6 before adding 20 pounds of calcium chloride to a ~23k gallon.
After 3 and 6 hours, FC still at 6.

After 24 hours, FC had fallen to 4, which is about normal. pH 7.4. Just took a swim and no chloramine/public pool smell.

Browsing through the thread, some folks postulated impurities in the calcium chloride powder, so I don't know if that made a difference. I bought 25 pounds of the Pool Mate brand and the packaging notes "100%" calcium chloride. I made sure to thoroughly dissolve the powder in a 5 gallon bucket (weighed out in 3-5 pound increments) before spreading it all around the perimeter.

 

[Buggs]

Another date point countering the theory of a Ca/Cl link.

I added 9.0 lbs of Ace Hardware's "O-ACE-sis" (94 - 100% calcium chloride). This was just a tweak to get the CH from 175 (7 drops) up to the 200ppm (8 drops) minimum for my gas-fired heater. FAS/DPD remained unchanged at 8.0 between the pre-application reading last evening and another reading 10 hours later. All test results except CH were unchanged.

Aside: This is the first time in 25 years that my CH has dropped below 200ppm. This summer, the pool developed a slow skimmer leak. During my diagnosis a few weeks ago, I did a small water draw-down & refill. My fill water has a CH of 100, so it seems I likely diluted the calcium.