Missing CA

[skillset]

In the quest to further prevent metal stains my 10K FG IG pool, I added 15lbs of Calcium, as a suggestion. I started with 0 and I think I got it up to about 250. I was having trouble with reading my test kit but I believe it got me to 250.

About 4 days after adding the Calcium, my pressure on the (sand) filter had drastically reduced (10lbs) and return jets had bad flow. This never happened since I've owned the pool - I rarely have to backwash. I backwashed and it restored the pressure back to normal. After that, my Calcium tested 0. I had the Calcium tested at Lelie's today and they too got 0. They tested it twice and they were very confused when I told them I added Calcium just about 2 weeks ago. I can only surmize that the filter grabbed all of my Calcium !! At the same time I put in the Calcium there was a ton of sequesterant in the water and I did add some afterwards, as well. As I said, I'm battling with stains.

Could the sequesterant have done something with the Calcium for it to end up in the filter?

 

[Guest]

Could the sequesterant have done something with the Calcium for it to end up in the filter?

Yes, calcium IS a metal. You sequesetered it out! The rise in filter pressure was probably due to calcium phosphonate precipitating out. Once your sequesterant wears off I think you will find that you DO have some calcium, perhaps not enough, but some. How much sequesterant did you use. You must have really overdosed to get a reading of 0 ppm Calcium hardness.

 

[skillset]

I used a lot of sequesterant! Over the last 3 week, probably about 4 32oz bottles.

Everytime my pool goes over 5ppm Cl, my metal stains come back. Even with a low Ph of 7.0. CYA is 40. Boy - do I with the sequesterant could do a good a job on the other metals as it did with the CA !!! The sequesterant does remove the stains, but they come back as soon as the Cl is raised. Seems like it trapped the CA in the filter and now it's gone foreever. I don't believe I'll get it back.

Anyway -what do you suggest? Is there a good time to add the CA? Should I wait a certain period of time after adding the CA before adding sequesterant? Will the sequesterant always reduce the CA when it's added? Seems like with the pool chemistry I have this year, I will be using quite a bit of sequesterant throughout the summer, so should i just forget about the CA? I'm worried about my heater and low CA.

 

[duraleigh]

Skillset,

To the best of my knowledge, Ca will have no affect whatsoever on any staining issues you may have. That your calcium tests zero is another issue but don't put Ca in your pool to fight stains.

If Your priority is to resolve the stain issue, could you post a pic of the stain and a full set of test results?

 

[Guest]

Skillset,

To the best of my knowledge, Ca will have no affect whatsoever on any staining issues you may have. That your calcium tests zero is another issue but don't put Ca in your pool to fight stains.

If Your priority is to resolve the stain issue, could you post a pic of the stain and a full set of test results?

Dave,
He has a fiberglass pool and there is evidence that calcium does help prevent staining and cobalt spotting in fiberglass pools.

 

[Guest]

I used a lot of sequesterant! Over the last 3 week, probably about 4 32oz bottles.
THAT is an overdose!
Everytime my pool goes over 5ppm Cl, my metal stains come back.
Keep your chlorine low and add some polyquat 60 to prevent algae. Did you do an ascorbic acid treatment? Do NOT shock the pool for a few weeks!
Even with a low Ph of 7.0. CYA is 40. Boy - do I with the sequesterant could do a good a job on the other metals as it did with the CA !!! The sequesterant does remove the stains, but they come back as soon as the Cl is raised. Seems like it trapped the CA in the filter and now it's gone foreever. I don't believe I'll get it back.
Sequesterant is NOT what you use to primarily remove stains. You use ascorbic acid and then use a normal to double dose of sequesterant to keep them from coming back AND you need to bring the chlorine levels up very slowly. Once you get that done would be the time to add calcium.
Anyway -what do you suggest? Is there a good time to add the CA? Should I wait a certain period of time after adding the CA before adding sequesterant? Will the sequesterant always reduce the CA when it's added?
To an extent but it will only cause it to precipitate out if you overdose on the sequesterant!
Seems like with the pool chemistry I have this year, I will be using quite a bit of sequesterant throughout the summer, so should i just forget about the CA? I'm worried about my heater and low CA.

 

[skillset]

Yes - I'm adding CA as a preventative per Waterbear's suggestion in this post: http://www.troublefreepool.com/fiberglass-pool-stains-t6300.html I am not using it as a primary stain remover.

The problem I was experiencing is that even once the Cl was raised (and I'm not talking shock level) the stains re-appeared. And, the more sequesterant was the advice I got to remove the stains. It really seems as though the concentration of metal must be so high in the pool, the metals are falling out very easily. Right now, the pool CYA is 40 and metals start to fall out at a Cl of 5.

Yes - I have tried the A-acid treatment. Twice. Both times they work great. Both times added sequesterant (per the treatment direction). Results only lasted about 4-5 days. That's it. Stains started re-appearing. Frankly, I'm tearing my hair out this season.

Right now - pool is moderately stained, so I'm back to square 1. Can't help but wonder how much sequesterant is in the water despite the stains. Somehow the key this years seems to be very tightly controlling the Cl. Not too hard to do w/bleach.

Is no CA bad for my heater? I used the heater (3 yrs old) a lot in APril/May and can't help wonder if this is the source of all this metal this year.

 

[duraleigh]

Skillset,

It strikes me that you could save a lot of time and trouble if you simply haul in water and replace the metal-filled water in your pool. Is that an option? It sounds like you're not getting much use from your pool in it's current condition and that would surely solve your problems.

 

[frustratedpoolmom]

Did you have any period with very low ph? That can corrode the innards of your heater and lead to the metals in your water. I don't think calcium is an issue with heaters, despite the many myths out there, but I know low ph is.....

 

[skillset]

Nope - never run the heater below a ph of 7.2. It's good to know that lack of CA will not damage the heater.

Actually, we've not missed a day in the pool yet, so this issue is basically a cosmetic one. Annoying, but not preventing use of the pool.

Honestly, I don't really know the source of the metals in the water. When the pool was built and filled 3 summers ago, they tanked in water - I don't know the source. Since then, with rain and use of a solar cover to minimize evaporation, I've rarely used my own tap water, which is city. This season, I've not added any.

Another frustrating thing is that I have an iron and copper test and both show 0. I would be very willing to dump some water and refill if I knew that was going to work. Last year, I didn't have too many issues with stains, but this year I do. Perhaps the rain is loaded with metals?

The good news here is the A-acid works great and fast. I just need to find a Cl level low enough to comply with the recommend Cl charts to keep the stains at bay.

My big questions about the A-Acid treatment:

1. Why wait 24 hours to add Cl? If the stains disappear instantly, why not start adding Cl?
2. What exactly does SLOWLY mean when adding Cl after the treatment? If I want to target 4ppm Cl and my pool is at 0, do you enough Bleach to get to 4ppm?
3. Trust me, I completely understand that shocking the pool after the treatment brings the stains back. If I bring my Cl just slightly about target, I'll get the stains, so I know. But, what is the significance of waiting 3 weeks? What happens in that 3 week time period that will make re-staining more probably with higher Cl?

 

[Guest]

My big questions about the A-Acid treatment:
Understand that ascorbic acid is a reducing agent (anti oxidant). it changes the colored metal stains into colorless ones that are soluable in the water. The sequesterant is to 'deactivate' the newly dissolved metal ions.
1. Why wait 24 hours to add Cl? If the stains disappear instantly, why not start adding Cl?
Because Cl is an oxidizng agent and it oxidize the metal back into a colored stain if added too quickly, as you have found out!
2. What exactly does SLOWLY mean when adding Cl after the treatment? If I want to target 4ppm Cl and my pool is at 0, do you enough Bleach to get to 4ppm?
NO, raise the FC no more than 1 ppm per day. It will take several days before the chlorine holds at all since the first job the chlorine has is to destrly (oxidize) any excess ascorbic acid. This is why it is a good idea to add polyquat 60 to help keep the algae from blooming and also why it's a good idea to do a stain removal in cooler weather. Best way to introduce the chlorine is right in the skimmer so if any staining occurs it will most likely stain the filter. IF (and only if) you are willing to run your pump 24/7 then place a trichlor tablet in your skimmer basket to provide a constant source of chlorine at first.
3. Trust me, I completely understand that shocking the pool after the treatment brings the stains back. If I bring my Cl just slightly about target, I'll get the stains, so I know. But, what is the significance of waiting 3 weeks? What happens in that 3 week time period that will make re-staining more probably with higher Cl?

this ensures that all the ascorbic acid is gone and that the metals are fully sequestered. You still need to keep adding maintenance doses of sequesterant weekly to monthly, depending on how high your metals were to begin with.