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but the takeaway is the more CYA you have the more chlorine you need and the only practical way to reduce CYA is replace more water. If you can reduce CYA to around 50, that would be good so if it really is 100 now, replacing half the existing water will do it.
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My chemistry problems have only appeared within the past month when I got a little lazy and wasn't checking my readings at least a couple of times a week. The high CH problems surfaced within 3 months of the initial plaster application (and pool was maintained by service company) and now within about 6 months of the 2nd plaster application, which I've been in control of. I have no pitting or etching, plaster feels smooth to the touch, just some grey-ish scaling in a few small areas that seem to come and go (more visible some days, others not). Have no idea what's causing this but my plaster is not "dissolving." If you can provide a research link that addresses plaster loss as a result of high CH and CYA that isn't marked by visible changes like pitting (because I think I've read the vast majority of them and none of the causes fit my situation) I'd be anxious to read it.
Thanks for your reply. I've read most of those articles you listed recently and have a better understanding now of the link between CYA and chlorine. You're right, I'm getting closer but need to do another 1/2 water replacement. It's just with being in a drought, I feel bad about throwing water down the drain. I've used my hot tub as a water storage tank since my last drain and now it's full again since I drained half the pool yesterday (it's not heating or being used right now). We also just got about 3 days worth of rain showers so even if I de-chlorinate the pool water, I don't need to irrigate anything...I know, I'm just trying to mitigate water usage. We're due to warm back up into the 90's though so in a couple of days I'll de-chlorinate, drain and refill the pool. I'd still like to know what causes significant increases in CH, and are readings between 300-600 exceptionally high or still within acceptable limits?I’m going to take a crack at laying out a wholistic approach but I defer to the experts provide you with the details.
The stuff in water chemistry all works together. If you change one thing, the other things still need to be taken into account to achieve balanced water. This article is something you already know but it pays sometimes to just go back to basics and think it all through.
ABC's of Pool Water Chemistry
There are several items things every pool owner should know about swimming pool water. We share details on the basics of Pool Water Chemistry.
Your CYA is still too high. This article is likely more than anyone wants to know about CYA
CYA - Further Reading
To replace water, take a look at the pitfalls and methods in this article:
Draining - Further Reading
Your pH is too low to get balanced water with the other stuff in your water chemistry. With your current TA , CYA and pH, it would actually be difficult to maintain that low — unless you are still using tabs it will rise on its own. You can aerate to speed it up. Not important right now because you still need to replace more water to lower your CYA so no sense futzing with that now. Once you get your CYA under control, use poolmath to help balance the other elements. Tabs lower pH; stop using them (if you haven’t already). Use liquid chlorine.
PoolMath
You need to maintain your FC level based on your CYA. A handy chart tells you exactly where you want to keep it. Use liquid chlorine.
The Free Chlorine and Cyanuric Acid Relationship
Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.
If in your shoes, I would:
1. test CYA per the diluted method posted earlier in this thread — you need to know if it’s really 100 or if it’s even higher.
2. Replace enough water to get your CYA around 50. If it’s really 100 that means replacing half the water.
3. immediately after that add liquid chlorine to get FC up to the levels on the chart
4. do a full set of tests and post results to sort of get a “sanity check” from the experts for next steps.
You seem to be getting much closer to the finish line but still a little ways to go.
Pool dimensions are roughly 14x10' with half being about 4 ft deep and the other half Baja shelfs about 18 inches deep.
I think you have a lot going on and if it were me, I’d stick to the plan I outlined and ask the experts for advice from there. Can’t do much about the water demand now. To fix the pool, you have to either replace the water or call a reverse osmosis operator.
The only way for CH to increase is for more calcium to be dissolved in the water. If you aren’t adding it yourself, it’s coming from somewhere. Plaster is composed of calcium and the huge surface area allows calcium to dissolve for a while without visually affecting the appearance. Other possibilities are fill water and I suppose incidental amounts from chemicals added.
Yes, totally agree that the CH is "coming from somewhere." I've researched this issue and all I've been able to find is situations where CH is high, CYA is high and pH is low, that the plaster shows pitting, etching and is rough to the touch. To me that makes sense as you can visualize material (calcium) being drawn out of the plaster and leaving behind evidence. What I haven't been able to find is an explanation of how CH can become so high without the plaster showing signs of damage? If the answer is that would take at least a year then someone needs to say that, or if plaster can lose a significant amount of calcium before becoming pitted or etched, then they need to say that. I just haven't come across those answers in any case I researched. I thought I'd repost this as it shows the chemical timeline during last year's plaster problem. Was the CH going up because the TA was higher than what it should've been? Also, the "CL" readings were what the main't company jotted down. Does anyone know based on the numbers, if this was TC or CC? Thanks.
).No one can answer that question as it all depends on how corrosive your water is and there really aren't enough good data to make that determination. You are taking a big chance though, as the corrosive conditions continue, you might get to the point where pitting, etc. occurs. If it were me, I'd want to make sure I didn't end up there and watch my chemistry closely (using good data from TF-100 or equivalent), particularly CSI, from here on out.
Yes, I am working on getting back to a regular schedule and those readings are very erratic but these were the results of a "professional" pool maintenance company. I believe their poor job resulted in ruining my initial plaster. I'm just seeking confirmation of that here so I can proceed with appropriate action against them. I have a very hard time understanding the chemistry relationships between high and low levels of TA, CYA and CH. And I've taken college chemistry courses! I also have read several TFP articles and other web topics on the subject but they tend to become very convoluted and I can't always follow what's chemically going on between all of these compounds. That's why I keep asking the questions I do because I'm hoping someone can answer so it makes a connection in my muddy brain. And no one has yet answered my question about "dissolving plaster." If significant calcium is being drawn out of it, will it show signs of that? (ie, pitting, etching, rough feel) or can a situation exist where the plaster doesn't show any physical or visual signs? Thanks!
Depends on the sensitivity of the test.
Keep the CSI in the -0.3 to 0.0 range and the plaster will be fine.
Thanks for your answer about the corrosive plaster issue. Of course it'd be nice if people could definitively know at what points water chemistry starts to visually affect plaster, but I get it. Not sure what "TF-100" is and I am trying to understand about the CSI but it is difficult for me. (I use a Taylor 2006 test kit) Sigh...the 1st plaster job is a long story but essentially, I lost all blue coloration within 3 months of application. I did not have $1000 to get the plaster tested for colorfast blue pigment, but the pools plastered right before and after mine with the same material, did not suffer color loss. Also, the plaster was applied on a perfect day in April so no extra calcium chloride was needed to quickly cure the cement. At one point about a month later, the maintenance guy dumped way too much acid in the pool enough where the plaster under the return jet on one shelf turned black. I also think they used way too much chlorine because initially for at least 2 weeks there were 2 pucks in the floating dispenser. (Does anyone know what the company's CL reading indicates - CC or TC?) I think this, along with the high TA levels throughout those months, adversely affected the brand-new plaster that was still curing. I also contacted the plaster manufacturer and they insist they only use colorfast blue pigment (DiamondBrite made by SGM). I've also talked to the National Plaster Council and they have no idea what could've happened. That's why I'm trying to better understand the relationship between TA, CYA and CH so I can hopefully uncover a logical reason. The articles I've read don't really tell me how the chemical reaction can affect plaster (especially in my case) so I'm desperate for someone to explain this relationship in very simple terms. I've taken chemistry classes so I can follow the logic to a point in these articles but I have yet to find one that explains what happened in my case with my particular chemical levels. There's always one component that was high when mine was low, or low when mine was high so I haven't been able to find something good enough to present to a judge in a court case. So far the only good argument I have is the chemistry levels were never held within industry standards by the main't company and this is what led to my color loss.
Get the app to help you manage the chemistry.
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Ok, I've seen this form and I will insert those readings from last year and see how they affect the CSI. That might answer my pressing questions as to whether the levels maintained by the pool service company contributed to my first plaster problem. This profile picture of my pool you enlarged was the only picture I have of my original plaster taken the next day after application. I'm attaching a time-lapse photo that shows what happened to the color between April and Nov of last year. The photos are actually quite generous in showing blue color as the real situation was much worse and far more greyer. The last image was after the pool main't supervisor tried to coax the remaining blue pigment to become more visible but it never came close to reaching the original. Also the second picture shows a closeup of the plaster during the middle stage. You can see the cream layer has dissolved away and by chipping a piece of the plaster you can see that the original color is still present. However, when i tried to sand off the surface, it only revealed a very dark bluish grey color so that option didn't work. Neither did an acid bath that was done before I applied the 2nd roll-on plaster layer (Sider-Proof). The very last image is what my pool looks like now.
