Help! White precipitate

[dirk_darkly]

Hi All,

I am a new pool owner with a pool service and I'm struggling with a new problem. Any insight would be greatly appreciated! Here is the timeline and how things developed;

About 3 weeks ago I had an algae outbreak in the pool. The pool was cleared up by the pool service with 1gal liquid chlorine, 1lb Calcium shock, and 6oz of clarifier.

About 2 weeks ago, I cleaned my filter cartridges myself (the psi had gotten into the clean range). I used a garden hose as instructed in the users manual. All seemed well after cleaning for a few days.

About 1.5 week ago, pool service added another 2gal of liquid chlorine and another 1lb calcium shock. Since that time, the pool got very cloudy/milky in color and a white precipitate formed on the bottom of the pool. I usually see the white powder forming at the bottom after shock, but this is the first time it didn't clear up after a few days.

About 1 week ago, the pool is still cloudy with a lot of white precipitate. Pool service suggested that I may have introduced an issue with the filters during cleaning. I reassembled and cleaned the filter to see if I mixed something up...the filters seem like they properly seated. When I hosed them off a lot of white stuff came out of them.

Since then, I've been running filter overtime and running my vacuum frequently. I've been brushing the white precipitate into the water, which causes it to get cloudy. Bit by bit the water has gotten clearer and the powder less. The water now looks clear but there is still a film of white precipitate all over the pool. There are some more highly concentrated areas of white substance at corners and on steps.

My questions to the forum are...

1. What is likely cause of white powder/film?
2. Is there a likely problem with filter, that I may have introduced during cleaning? Should the filter cartridges be replaced as pool service suggests?
3. What to do about high free chlorine, and could this be contributing to white powder problem?

I got a test kit today and tested all the levels. This is what I found;

• Free Chlorine: 10 ppm
• Combined Chlorine: 0 ppm
• pH: 7.4
• Total Alkalinity: 80 ppm
• Calcium Hardness: 360 ppm
• CYA: < 30 ppm...Not discernable with my test kit (Taylor 2006C)

I ran the Free Chlorine three times since it seemed so high...it is the FAS-DPD test from the Taylor 2006C kit.

Pool Stats

• Inground about 16,000 gal?
• Plaster walls
• Pentair Clean and Clear Plus 420 Cartridge Filter
• Dolphin Cayman Vacuum

Thanks again in advance, I'm enjoying learning about maintaining the pool. I'm working through the pool chemistry articles but this seemed like something that could benefit from some experienced advice.

 

[dirk_darkly]

Quick Edit: I cleaned the filters again, lots more white stuff came out. It seems to be a chalky consistency without any odor that I can discern.

Thanks again for any insight.

 

[Rancho Cost-a-Lotta]

Welcome to TFP!

Great move in picking up a good test kit and posting results.

The white stuff could be calcium precipitate from the use of calcium shock, but your TA ph and CH numbers don't really support this theory.

What type of filter do you have? It is a DE filter?

Are you able to collect any of the white material? DE is very fine, like powder.

 

[Rancho Cost-a-Lotta]

Sorry, I missed that your filter is a CCP, non-DE filter. See if you can collect some of the white material. Put a couple drops of muriatic acid on it. If it fizzes and bubbles, we know its calcium-based.

Photos may help us out as well.

 

[dirk_darkly]

Thank you so much for the response! As I new pool owner I am extremely grateful that a community like this exists.

Since posting I've been reading the pool chemistry book that came with the Taylor kit. I read about balanced water and the Saturation Index. The symptoms seems to be consistent with scaling water, but the SI is within the acceptable range, and on the corrosive side (about -0.1 according to the Taylor watergram). If I understand correctly free chlorine is unrelated to water balance, except so far as pH is concerned. If that is the case I'd like to narrow my question to the cause of the scaling? problem, despite having supposedly balanced water.

I don't have muriatic acid on hand but I can get some tomorrow to test the white stuff. In the meantime I attached some photos.

Thanks in advance for any insight!

Here is the pool bottom, you can see where I pushed the brush and some precipitate on the steps

Here is me hosing the white stuff out of the cartridges. Done this a couple times.

Here is some of the white stuff left behind on the concrete after hosing


White stuff on everything, even the robot. In this pic it's already been hosed off once.

 

[PoolStored]

This is a bizarre case. Let's get some additional eyes. @JoyfulNoise @mknauss @ajw22

Are any of these chunks still around? Do the muriatic test on these chunks.



Very interesting.

 

[Rancho Cost-a-Lotta]

With no MA, try vinegar.

 

[JoyfulNoise]

Its calcium carbonate scale from all the calcium hypochlorite shock. It’s well known to cause water cloudiness and scale. You can have a negative saturation balance and still get scaling … the saturation index just tells you whether or not the water is capable of absorbing or holding calcium, not if it will do so. Once calcium carbonate scale forms, it doesn’t dissolve easily, even in very negative SI water.

I would suggest you perform the CH test again and make sure you are carefully following the directions.

It sounds like you have had a lot of scale in your pool and that the pool service was routinely using cal hypo shock. That’s not good where you live (LA) because water is very hard out here in the west.

 

[dirk_darkly]

Wow, thank you for all the input.

I put some apple cider vinegar on the white stuff, and it did indeed bubble.

I redid the tests, I got the same for Total Alkalinity and Calcium Hardness but pH was higher. With a water temp of 70 this moves my SI to around 0.2.

• Free Chlorine: 7.5 ppm
• pH: 7.7
• Total Alkalinity: 80 ppm
• Calcium Hardness: 360 ppm
• Water Temp: 70

So if I'm understanding correctly, the white stuff is calcium carbonate scale from the shock, and it doesn't dissolve easily. What would you all recommend for next steps? Do I just keep brushing and filtering until it is all out of the pool? Given how long its taking to filter it out, do you think there is something wrong with my filter?

Thanks again!

 

[JoyfulNoise]

Letting the precipitate fall and then doing a slow manual vacuum to waste would be best. But if you don’t have the equipment setup to do that, then all you can do is brush and filter until it clears. That could take a while. Unless there’s something obviously wrong with your filter reassembly it should be working fine.

What make and model is your filter?

 

[JoyfulNoise]

I see it in the first post. Please update your Signature under your profile settings so that your pool equipment info gets appended to every post. It’s hard to help when we have to constantly look back at old posts to find the info.

Your CCP filter has an internal-ring on the bottom manifold assembly that should be lubed with silicone lube every time you open the filter and clean it. You can also put a very thin layer of silicone lube on the top and bottom manifold ports that the blue rubber portion of the cartridges plugs into. It is possible over time for those rubber end caps to degrade or lose their shape and tightness of fit. Also make sure the air bleed screen is clear and tightly seated onto the pipe.

 

[Rancho Cost-a-Lotta]

Could you please confirm the sample size you are using for CH test.

 

[dirk_darkly]

Hi All! Thanks so much for your responses. Added a signature with my stats, hopefully I did that right. That is a great suggestion about the silicone lube on the filter. I had put a little on the cartridges the last time but not sure if it was enough. I also don't think I noticed the internal ring you mentioned. So far things have not been improving...in fact possibly the scaling is worse.

Here is the testing update;

I'm using 25ml for CH test with the Taylor test kit. This morning I got these #'s

• Free Chlorine: 3.2 ppm
• pH: 7.8
• Total Alkalinity: 70 ppm
• Calcium Hardness: 330 ppm
• Water Temp: 68

On Saturday (2 days ago) I went to Leslie's for testing and got this. Fairly close to what I was getting with the exception of Calcium Hardness, they got a lower reading. One caveat is that this sample was in the car for a couple hours, not sure if that would affect the relevant #'s;


I've been brushing and filtering all weekend, but each time in the morning after the filter is off for a while there is a new crop of white powdery stuff on the bottom. I haven't re-assembled yet with a more liberal amount of silicone.
Here is the white powder this morning;


And now I'm noticed crusty looking white stains around the pool. Given the former milkiness and white powder everywhere, it is possible these have been here a while and that I am just noticing them now.


Aside from cleaning and lubing the filter again, any suggestions on how to proceed? Is it possible to get those crusty white stains off the plaster?

Thanks again!

 

[Rancho Cost-a-Lotta]

Continue to collect and remove as much of the scale as you can. Read the article Below on calcium saturation index. Try to maintain CSI around -0.30 by adjusting ph and TA. This should help cut down on some of the scale.

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

Calcium Scaling

Calcium scale on your pool is something we all want to avoid. With some elbow grease and a pumice stone for pools we can help you remove this eyesore.

www.troublefreepool.com

 

[JoyfulNoise]

It’s not shown on the parts diagram but the bottom manifold #8 plugs into the outlet pipe assembly #17. That pipe has an o-ring around it in a groove. The bottom manifold should get pulled off with every cleaning and that o-ring should be inspected and lubed. Otherwise dirty water will by-pass the filter elements. It’s a common problem you can easily see on a DE filters because you will immediately see a cloud of DE coming out of the returns. With a cartridge filter it’s harder to detect.