Do I need to increase CH?

Ezun

Gold Supporter
Jul 27, 2017
53
Edwardsville, IL
I have essentially the same question, and my OCD makes me want to increase my hardness.
I’m coming off a SLAM - I wouldn’t have done this out of the gates (just opened the pool on 5/2) but my Pool Company opened the pool for us and immediately threw shock into the pool, so I figured I would continue the process and take advantage of the high FC.

My test this morning had results of:
FC = 9.5
CC = .5
CH = 280
TA = 70
CYA = 55
ph = 7.6
Salt = 3200
Borate = 80

I feel compelled to raise my CH to 350.
The other minor issue I’m having is that the metal around my lights has a slight pink “dusting” on it. It seems to rub off with my hands - but not sure what that is. Is that the start of corrosion, and if so, I’m thinking low CH might be a contributing factor.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,446
Laughlin, NV
What is the CH of your fill water? Do you add that fill water during the summer due to evaporation, backwash, splashout, etc?

At this point, your chemistry is fine. CH level does not lead to any type of corrosion of metal. pH is that culprit, along with the use of sodium bisulfate (dry acid).
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
I have essentially the same question, and my OCD makes me want to increase my hardness.
I’m coming off a SLAM - I wouldn’t have done this out of the gates (just opened the pool on 5/2) but my Pool Company opened the pool for us and immediately threw shock into the pool, so I figured I would continue the process and take advantage of the high FC.

My test this morning had results of:
FC = 9.5
CC = .5
CH = 280
TA = 70
CYA = 55
ph = 7.6
Salt = 3200
Borate = 80

I feel compelled to raise my CH to 350.
The other minor issue I’m having is that the metal around my lights has a slight pink “dusting” on it. It seems to rub off with my hands - but not sure what that is. Is that the start of corrosion, and if so, I’m thinking low CH might be a contributing factor.
I see a couple things
1) If you're giving CH by 10s, you're using the 25 ml sample. That means that a) you're using way too much reagent and b) your wrist probably tires doing the test, which can skew the readings. My CH value changed dramatically when I switched to a speedstir. Anyway, if you use the 10 ml sample, you go by steps of 25, which is good enough. The difference between 275, 280 and 300 is insignificant in poolmath
2) CYA reading should be rounded up to 60. It's a logarithmic scale, so halfway between marks is not the average of the two.

If there is CH in your tap water, CH is going to go up through evaporation and refill. Once the Summer heat hits, it can climb pretty fast. You may find yourself cursing yourself for raising CH early in the season because late in the season you have to replace water, and by doing so, you're losing CYA and salt.
 

Ezun

Gold Supporter
Jul 27, 2017
53
Edwardsville, IL
Thank you ALL... this is great!
to what end? What is the CH of your fill water?
This is a good (and fair) question - I don’t know, just my OCD wants it to be “within range”. I’m also a bit concerned it will leach Calcium out of the plaster.

It’s embarrassing to say, but I’ve never tested my fill water. I literally tested it just to respond to you guys.
99884

Note also, my kids like it REALLY warm, so the pool is going to stay in the high 80’s most of the time (87-ish)

What is the CH of your fill water? Do you add that fill water during the summer due to evaporation, backwash, splashout, etc?
At this point, your chemistry is fine. CH level does not lead to any type of corrosion of metal. pH is that culprit, along with the use of sodium bisulfate (dry acid).
Fill water CH = 100
Yes, I will add fill water during the summer.

What should I do about the pink dust/corrosion to get rid of an prevent it?

Your numbers all look good i wouldn't change a thing unless you have a SWG and then i'd raise the CYA to 70.
Yes, thank you, I’m working on this and have some stabilizer in a sock in one of the skimmers to bring it up.

At the moment I'd say no as well. I would however like to know your water temp.
Water temp is 71

I see a couple things
1) If you're giving CH by 10s, you're using the 25 ml sample. That means that a) you're using way too much reagent and b) your wrist probably tires doing the test, which can skew the readings. My CH value changed dramatically when I switched to a speedstir. Anyway, if you use the 10 ml sample, you go by steps of 25, which is good enough. The difference between 275, 280 and 300 is insignificant in poolmath
2) CYA reading should be rounded up to 60. It's a logarithmic scale, so halfway between marks is not the average of the two.

If there is CH in your tap water, CH is going to go up through evaporation and refill. Once the Summer heat hits, it can climb pretty fast. You may find yourself cursing yourself for raising CH early in the season because late in the season you have to replace water, and by doing so, you're losing CYA and salt.
1) You’re right, I need to start using 10ml samples
2) Got it. I’m currently trying to raise it to 70.

Your points are helpful. I think I’m going to hold off.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
The "dusting" around your metal light ring is likely a pH related issue.....hard to tell but it is not related to CH.

I would leave the CH at 280 (which will be within our new limits (not yet published) of 250-400). With a fill water of 100, your CH will increase slowly or perhaps not at all depending on rainfall, splashout, etc. You CH management is easy to control
 
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onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
976
Utah
If you just opened up your pool, I would think that the pool water temp is well below 71 degrees as you stated. Even if the water temp is 71, I would suggest (as Texas Splash advised above) that you raise your pH to 7.8 to 8.0 until the water warms up during the summer as you plan to do. Raising the pH will help protect your plaster and prevent leaching (etching) out of calcium as you are correctly concerned about. Raising the pH would be an alternative to raising your CH for proper water balance and protecting your plaster from damage during cold water temperatures.

The pink dust on your light may be from copper in the water, or just left over dust from winter. Check the smoothness of the plaster to see if there is any dust or scaling issues. You might want to check the copper content.
I am also curious as to how old or new your pebble sheen finish is.
 
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Ezun

Gold Supporter
Jul 27, 2017
53
Edwardsville, IL
If you just opened up your pool, I would think that the pool water temp is well below 71 degrees as you stated. Even if the water temp is 71, I would suggest (as Texas Splash advised above) that you raise your pH to 7.8 to 8.0 until the water warms up during the summer as you plan to do. Raising the pH will help protect your plaster and prevent leaching (etching) out of calcium as you are correctly concerned about. Raising the pH would be an alternative to raising your CH for proper water balance and protecting your plaster from damage during cold water temperatures.

The pink dust on your light may be from copper in the water, or just left over dust from winter. Check the smoothness of the plaster to see if there is any dust or scaling issues. You might want to check the copper content.
I am also curious as to how old or new your pebble sheen finish is.
@onBalance - Thank you for your help. To confirm, my water temp was 71 when I took that test - we have a Pentair Heat pump heater so we turned it on the minute we opened the pool (water was 56 degrees). The good news is that my PH was high the day we opened the pool when the water temp was low - so that should have caused very little damage to the finish throughout the winter.

Curious, most everything I read says to keep PH between 7.2 and 7.8 - so I split the difference and shoot for 7.5. I know you guys know what you're doing and I'm trying to understand why I should have my PH so high? I'm still learning and it sounds like higher temps (probably going to keep the pool about 85 all summer) make a BIG difference in what my water chemistry should be. High PH, based on my reading, is not good - but I'm a total noob (just started doing my own water maintenance at the end of last season and I'm pumped to do it this season, so I want to get it right!

Today's test results:
Temperature81
Free Chlorine (FC)8
Combined Chlorine (CC)0.2
pH7.6
Total Alkalinity (TA)80
Calcium Hardness (CH)275
Cyanuric Acid (CYA)50
Salt3400
Borate80
Saturation Index-0.34
Unfortunately you can see I miscalculated and dumped in to much Borax last season and I'm just going to let it ride throughout the summer as I backwash and get rid of water it should slowly come down.

As for copper - I haven't even started testing for metals - which I guess is something I need to figure out how to do now to see why I have that pink dust on the metals in my pool. Any quick links to testing for metals in water would be helpful! :)

My Pebble sheen finish is just shy of 1 year old, they put in the pool last summer. I've only walked on the sun ledge (kids have been in, but not me) and the finish feels the same as last year. The "pink dust" started last year and I wiped most of it off, but not all of it would come off 100%. Thinking of using a magic eraser on it to get it really clean - not sure how that would affect the longevity of the metal.

Thank you!
 

borjis

LifeTime Supporter
Aug 19, 2014
3,011
Pacific NW
The metals test kits are super expensive.
Many have suggested using free pool store testing to get some kind of idea on metal content in the water.
Though it may or may not be accurate it should give you some insight.
 
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JamesW

TFP Expert
Mar 2, 2011
16,595
Pink is fairly unusual. The three things that I can think of are manganese, copper cyanurate or pink bacteria.

Do you have a picture of the pink?
 

JamesW

TFP Expert
Mar 2, 2011
16,595
Looks strange. I'm thinking that it might be corrosion behind the light in the niche.

Possibly a stray current if you're getting excessive corrosion of the light or niche or parts in the niche.

It might be iron. When is the last time that you took the filter apart and cleaned it?

The color of the filters before you clean them should give us an idea about what's in the water as it should be catching on the surface of the filters.
 
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borjis

LifeTime Supporter
Aug 19, 2014
3,011
Pacific NW
ya know after seeing that photo I remember seeing that stuff on my last house/pool light.
I never did figure out what it was. But the pool was perfectly balanced and I only lived there for a year.
 

Ezun

Gold Supporter
Jul 27, 2017
53
Edwardsville, IL
It might be iron. When is the last time that you took the filter apart and cleaned it?

The color of the filters before you clean them should give us an idea about what's in the water as it should be catching on the surface of the filters.
I assume this answer is bad: I haven’t cleaned the filter yet. I guess I should do that and take before and after photos. And, I’m sure I can find this somewhere, but how often should I clean the filter - annually?

@JamesW - should I go pull and clean the filter now?

Curious if you guys have tried something called “culator” (pronounced See-You-Later), it’s supposed to pull metal out of your pool water by just putting it into your pump basket. Here’s a YouTube video of some guy talking about it
Go to the 5:27 time stamp to see it clearly described and used over a 4 day period.
 

JamesW

TFP Expert
Mar 2, 2011
16,595
If the filter has never been broken down and cleaned, I would recommend that it be done.

The dirty filter can help diagnose what's in the water.
 

Ezun

Gold Supporter
Jul 27, 2017
53
Edwardsville, IL
If the filter has never been broken down and cleaned, I would recommend that it be done.

The dirty filter can help diagnose what's in the water.
Sounds like a project for tomorrow.... watching a few videos on how to clean and reading the manual. Sounds like I need to do this every 6 months. I think the pool is open for less time than that, so probably every spring when we open it, right?