Is it ok to add CH increaser if the DE grids are no longer in the filter?

[anthonypool89]

I'm not putting them back in for the last few days before closing (long story), but noticed that the CH should be brought up a bit. I know it always causes lots of foam in the pool shortly after adding it, but then subsides. Any difference without having the grids in? Can't see that it'd do any harm (?) These last few days I'm basically just circulating water. I usually do have the grids in right up until the end but things didn't work out that way this season.

 

[YippeeSkippy]

I can't say I've ever seen Calcium Increaser foam?? It can make things a little cloudy sometimes and it does have some "heating up" ability so maybe that's what you're seeing..... or its because of the Bacqua maybe? No problem adding it cause you sprinkle it on the surface and brush it all over the place to help it dissolve.
I can't see how the lack of grids would matter? (unlike having the grids in without DE..that's a huge No-No!)

 

[duraleigh]

Not the answer you asked for but I am curious why you need CH? Typically not an addition made at closing. Can you tell me your current CH?

I don't have a DE filter but I see no harm in what you are contemplating.

 

[anthonypool89]

Hi Dave,

I'm at 180 on the CH. The past few years I typically brought it up to 230. My current numbers are:

pH - 8+ (will be bringing down to around 7.7)
TA - 100
Temp. - 81
SI - 0.62 (would like to get it lower before closing)

With the CH a bit higher then where it is now, there's less likelihood of the SI going closer to the corrosion zone as the water temp gets down towards 50. I check and adjust the pH occasionally during the off season as long as I can until (if) the water freezes. If I'm not mistaken, the current 180 level is probably considered too low anyway. I go more by what the overall SI is rather than what the individual readings are. So part of my concern can be seen in these 2 situations:

A) TA - 100
CH - 230
Temp - 50
pH - 7.7
SI - -0.16

B) TA - 100
CH - 180
Temp - 50
pH - 7.7
SI - -0.27 (much closer to the -0.3 level at which some treatment is suggested to prevent corrosion)

 

[anthonypool89]

I can't say I've ever seen Calcium Increaser foam?? It can make things a little cloudy sometimes and it does have some "heating up" ability so maybe that's what you're seeing..... or its because of the Bacqua maybe? No problem adding it cause you sprinkle it on the surface and brush it all over the place to help it dissolve.
I can't see how the lack of grids would matter? (unlike having the grids in without DE..that's a huge No-No!)

"Foaming" was probably not the most accurate term. As you said, it's likely the result of the heating process...or...some sort of interaction with the baquacil.

 

[duraleigh]

I am not a fan of CSI....particularly in a NE pool where calcium scale is insignificant.

Nevertheless, in the example above, I have a very hard time buying that INCREASING the CH in your pool lessens your tendency towards calcium scale. Can someone help me understand that?

 

[anthonypool89]

Dave,

I can only assume - in my limited knowledge of pool chemistry - that a higher CH level, generally speaking, corresponds with a slightly higher SI assuming all other parameters are the same such as in the examples. Why it happens is for someone else to explain. Isn't it correct that once you're above the saturation point (calcium level) it can become scale forming? I'm simply trying to stay farther away from the etching zone. As my pool contractor told me after doing the renovation, 'you can always take it off (scale) but you can't put it back on' (etching).

Interesting that you say calcium scale is "insignificant" here in the NE. Are you implying that if the SI level is consistently over +0.4 for extended periods there is little chance of scale forming?

 

[duraleigh]

Interesting that you say calcium scale is "insignificant" here in the NE. Are you implying that if the SI level is consistently over +0.4 for extended periods there is little chance of scale forming?

CSI is a helpful tool for those who cannot stay within normal TFP guidelines.......that most always means too much calcium in the fill water and also most always means that occurs in the desert Southwest and parts of Texas and California.

Test your fill water. Historically, Pennsylvania is not high enough in CH to cause you much concern. Stay within the guidelines suggested by TFP for CH, TA, and pH and I contend CSI is no longer important.

Nevertheless, in the example above, I have a very hard time buying that INCREASING the CH in your pool lessens your tendency towards calcium scale. Can someone help me understand that?

I'll stand by for the answer on this one.

 

[Leebo]

Concerning the foaming, what type of algaecide are you using?

Adjusting your CSI (edited to correct) for lower water temps before winter is a good idea as you aim to extend the life of your plaster. Your calcium level is rather low and needs to be increased as you had planned. I’d even check your CSI assuming the water temps are in the 40’s as just about everybody is expecting a rather cold winter this year. The foam that may occur after you add the calcium will likely go away in a day or two.

 

[duraleigh]

I am cool with adding CH to get to 250 (TFP guideline) but not to satisfy CSI. I am not sure what it means to adjust CH for cooler temps?

 

[Leebo]

Error on my part. I meant to type CSI but not CH

 

[anthonypool89]

Concerning the foaming, what type of algaecide are you using?

\

The regular baquacil products - their algaecide along with the Sanitizer, which is listed as "Sanitizer and algistat". I check frequently during the off-season and adjust pH as needed to try and stay as close to zero SI as possible. As the water gets much colder, the SI reading comes out much better if the pH is closer to or even at 8, so I'll sometimes add pH increaser over the fall / winter. For right now, though, closing with the water close to 80 degrees (darn!!!) pH has to be closer to 7.7. Otherwise the SI is in the scale zone. Even 7.6 is fine for now until the water temp starts to drop.

I get the feeling that TFP is not real big on relying on SI as a true indication of proper water balance. The company that renovated my pool advised going more by the overall SI than getting too hung up on any specific recommended range for each of pH, TA, and CH. That being said, however, with my usual habit of overthinking many things, they also told me to not try and "micro-manage" these numbers either - especially during the winter months.

Also...I'm not clear on what the exact difference is between CSI (as referred to in this thread) and just SI (?) I believe what I'm using is just SI (which, if I'm correct, is the same as LSI).

 

[ajw22]

I get the feeling that TFP is not real big on relying on SI as a true indication of proper water balance. The company that renovated my pool advised going more by the overall SI than getting too hung up on any specific recommended range for each of pH, TA, and CH. That being said, however, with my usual habit of overthinking many things, they also told me to not try and "micro-manage" these numbers either - especially during the winter months.

it takes months of water being out of balance for scale to develop. Scale does not happen overnight from short term changes in water chemistry.

TFP Recommended Levels - Trouble Free Pool are designed to maintain CSI balance if chemistry is kept within the ranges. That way most people do not need to learn about CSI management. It has become easier now that PoolMath calculates CSI.

Also...I'm not clear on what the exact difference is between CSI (as referred to in this thread) and just SI (?) I believe what I'm using is just SI (which, if I'm correct, is the same as LSI).

Read CSI and LSI - Further Reading

 

[anthonypool89]

ajw...thanks! I'll check out the link.....

 

[onBalance]

anthonypool89, I suggest your understanding of your pool water balance and situation is correct, and you should continue with your plan.
Adding calcium increaser (calcium chloride) is needed to avoid aggressive water conditions (that currently exists) and balance your water properly. That will especially help because of the upcoming cold-water conditions which increases water aggressiveness towards calcium. Adding calcium chloride will be very soluble as long as the water has a negative CSI (or LSI or SI, which do provide virtually identical numbers), and therefore, adding without filter grids installed won't cause problems.

Recommended Levels/Limits have been designed (based on the CSI) to provide some very simple guidelines for those who do not understand the CSI and how important it is for plaster-based finishes. Unfortunately, given that there are wide fluctuations in water temps and TDS which can't always be controlled, sometimes, even when the pH, TA, CH is within the recommended levels, pool water can still be overly scale forming or overly aggressive which leads to etching over time. That is the simple reality. And that is why Leebo correctly suggested that you raise the CH now and even adjust for even colder water temps coming up this winter. Two or three winters of aggressive water (lower than about -0.4 or -0.5) can result in significant etching which causes rough or pitted plaster. No one wants that to happen.

When water temps are within a narrow and reasonable range (and the TDS isn't high), then the recommended levels work very well. Since you seem to understand the CSI or LSI and how to adjust it, you are on the right tract.

 

[duraleigh]

sometimes, even when the pH, TA, CH is within the recommended levels, pool water can still be overly scale forming or overly aggressive which leads to etching over time.

So then I don't understand how you alter the pool chemistry so it is NOT overly scale forming or aggressive. You surely have to adjust one or all of those parameters to bring the water into a safe range. Doesn't that mean our TFP ranges are too broad, then? Do we need to rethink our suggested ranges?

 

[ajw22]

So then I don't understand how you alter the pool chemistry so it is NOT overly scale forming or aggressive. You surely have to adjust one or all of those parameters to bring the water into a safe range. Doesn't that mean our TFP ranges are too broad, then? Do we need to rethink our suggested ranges?

I suggest you use your superpowers and start a new thread to discuss this.

TFP guideline ranges seem to assume normal swimming water temperatures of 60 degrees and above. CSI gets very low when water temp is 40 and below. For those who keep their pools open through cold weather it can become a problem as Kim said.

for example...

Free Chlorine: 5.0
pH: 7.8
Total Alkalinity: 60
Calcium Hardness: 350
CYA: 30
Temperature: 35°F
CSI: -0.48

 

[duraleigh]

I thought about a new thread and, actually, this thread has remained on topic throughout and, to me, is a good way to help folks understand this subject better.

So let me go to your example. Those numbers look fine to me if I am a TFP pool owner.

Does the CSI calculation mean my pool will scale? Does it mean my pool will leach calcium from the plaster? I really have no idea.

The only issue I see is the CSI number isn't where you want it. Tell me what this pool water (with those numbers) needs to solve this problem.

 

[anthonypool89]

With the conditions mentioned in ajw's example, what I'd do is bring the pH up just a tad to 8 (assuming the water is free enough of ice to get in there and agitate it around a bit!) and then you'll be at -0.29 - a much better number. Even a bit higher than 8 would be better.

 

[ajw22]

Great. Lets discuss. Anthony just wants to raise his CH to 250. Here is what that would be with my chemistry:

Free Chlorine: 5.0
pH: 7.8
Total Alkalinity: 60
Calcium Hardness: 250
CYA: 30
Temperature: 35°F
CSI: -0.63

So what levers do we have to keep CSI in range at low water temperature? pH is already at the high end of the range.

You can increase TA to raise CSI. But that gets you onto the pH/TA yo-yo.

Or you can increase CH.

Or some combination of CH and TA adjustments for the winter that you need to undo in the Spring.

i leave it to Kim to explain the effects of CSI of -0.48 or -0.63 on plaster for a few winters.