White crystals forming on plaster

[JamesW]

Maybe calcium sulfate, calcium phosphate or calcium carbonate.

Put the crystals in acid to see what happens.

Dissolve some in water and then test the TA, Calcium Hardness, Phosphate and Sulfate levels.

Dissolve 300 milligrams in 1 liter of water and this will produce 300 ppm of the substance.

If it is calcium carbonate, the CH and TA will be 300 ppm.

 

[voidpointer]

Are your spa and pool connected? Your PM logs only show Data for the pool, where even at 52°F the CSI is quite positive. You actually want to know what the CSI will be at spa temperature. Yes, with increasing temperature, pH will go down a bit, but pH is already maxed out on the comparator scale.

How much of it's time does the spa spend at operating temperature?

Run some tests at spa operating temperature and log the results separately. You can define multiple pools/spas in PoolMath.

Yes the spa and pool are connected. I run spillover 2-3 times a day to ensure that it gets chlorine. I tested the spa once a while ago just to make sure the chlorine levels were high enough, but after that I don't test in the spa anymore. The pool might also have those crystals I just haven't checked. The water is so cold it hurts to keep my hand in it more than a couple of seconds.

What do you mean by "operating temperature"?

Do you ever use sulfate chemicals in the pool or spa?

I'm not sure what sulfate chemicals are. As of maybe 1-2 months ago I've been using trichlor pucks in a floater to keep my chlorine levels up. My research says that some people like to do this in the winter when SWGs don't operate at colder temps, and it's a bit more hands-free than liquid chlorine. My understanding is that this raises CYA but I want that anyway because I'm always manually adding it anyway. Besides that i just add my muriatic acid and that's it.

Check for phosphates and sulfates.

I don't know how to test for this. My test kit doesn't appear to have support for these.

 

[voidpointer]

The pictures of the scale is blurry.

Can you post better pictures?

The picture is blurry because the thing is about the size of a salt grain. I set it on top of a table in as much sunlight as I could. I had to really get close to get a good picture.

I can't even see the things in the pool through the water. So I can't take a picture that way.

If you can let me know exactly how I can take a better picture for you I'm willing to try.

 

[voidpointer]

Maybe calcium sulfate, calcium phosphate or calcium carbonate.

Put the crystals in acid to see what happens.

Dissolve some in water and then test the TA, Calcium Hardness, Phosphate and Sulfate levels.

Dissolve 300 milligrams in 1 liter of water and this will produce 300 ppm of the substance.

If it is calcium carbonate, the CH and TA will be 300 ppm.

I haven't forgotten about the first post you made for this test. I can probably test for TA and CH but not the other two. I am not comfortable handling acid beyond opening a lid and pouring it in a pool. Happy to try, though. What tools do you use to do this testing? I have a qt sized measuring cup -- do I pour MA in there and drop the crystal in and see what happens? When you say dissolve in water, do you mean pour the acid in a cup of water (after the crystal dissolves)? What tool do you use to measure 300mg of liquid? I apparently have a lot to learn here. Clearer instructions would help.

Thank you for your continued help.

 

[voidpointer]

Here's a few more pictures. If you look close you can see the pin-sized white flakes on the plaster. I checked the pool and I'm not seeing it. Seems to be the spa alone.

 

[JamesW]

What temperature is the spa?

Can you post all current readings?

 

[voidpointer]

What temperature is the spa?

Can you post all current readings?

Can I use a steak/cooking thermometer to measure the spa temp?

yes I will run my full suite of tests today since it's been about a month since my last full set. Do you want me to sample water from the spa or the pool for this round?

 

[JamesW]

Taylor’s phosphate test kit (K-1106) measures this elementary “free” form and is able to detect phosphate levels from 0–6000 parts per billion.

Phosphate Test Kit, 0-≥1000 or 0-6000 ppb

 

[JamesW]

Do you want me to sample water from the spa or the pool for this round?

Both.

Can I use a steak/cooking thermometer to measure the spa temp?

Get a pool and spa thermometer.

What is the approximate temperature?

Is the CSI being calculated at the pool temperature or the spa temperature or are they both at the same temperature?

Are you heating the spa?

What does the heater display show?

 

[voidpointer]

Both.

Get a pool and spa thermometer.

What is the approximate temperature?

Is the CSI being calculated at the pool temperature or the spa temperature or are they both at the same temperature?

Are you heating the spa?

What does the heater display show?

Any thermometer recommendations you'd like to share?

Currently, pool temp is 54F, spa temp is 57F.

CSI is calculated at pool temp since I do not sample water from my spa nor do I test it separately.

I heat the spa when the family uses it occasionally. This winter, it has had almost no usage. We've heated it maybe 2-3 times max since around November last year.

My heater has no display. I only see 1 water temp in iAqualink which will show the temp of the pool in pool mode and the temp of the spa in spa mode.

 

[voidpointer]

Taylor’s phosphate test kit (K-1106) measures this elementary “free” form and is able to detect phosphate levels from 0–6000 parts per billion.

Phosphate Test Kit, 0-≥1000 or 0-6000 ppb

I will go ahead and buy one. You also mentioned sulfates, is that something that needs to be tested separately, and if so how should I test for it?

Any reading material you recommend to understand more about what sulfates and phosphates are as it relates to pool care?

 

[JamesW]

Phosphates and sulfates are typically not an issue unless they are causing scale.

See what the levels are and address as needed.

Try keeping the CSI at -0.3 and brush the pool and spa daily with a nylon bristle brush to see if that helps.

 

[JamesW]

I don't know of a low cost sulfate test.

I found this, but it is $157.75, which is pretty expensive.

Sulfate Test Kit

This kit tests for Sulfate using the Octa-Slide 2 Comparator. Range and sensitivity is 20, 40, 60, 80, 100, 120, 160, 200 ppm SO42-.

lamotte.com

You might have plain calcium carbonate, so try to confirm or rule out calcium carbonate before buying a sulfate test kit.

 

[voidpointer]

How do I rule out calcium carbonate? Is that what the phosphate test is for?

 

[JamesW]

How do I rule out calcium carbonate?

Try some of the tests suggested earlier.

 

[voidpointer]

Maybe calcium sulfate, calcium phosphate or calcium carbonate.

Put the crystals in acid to see what happens.

Dissolve some in water and then test the TA, Calcium Hardness, Phosphate and Sulfate levels.

Dissolve 300 milligrams in 1 liter of water and this will produce 300 ppm of the substance.

If it is calcium carbonate, the CH and TA will be 300 ppm.

I still need some help here. How much acid do I pour into a cup for the crystal? I assume this is relevant to avoid dilluting the 300mg of acid in the next step...
I could use my coffee scale to measure 300mg of acid I guess. I don't have any other tools. So just to make sure I understand:

1. Pour some unspecified amount of MA into a cup (you'll provide amount)
2. Drop the crystal in
3. Fill another cup with 1l of water on the scale.
4. Pour in 300mg of the acid into that cup which is on the scale
5. Take a sample of the water and test for TA and CH

Let me know.

EDIT: Unless you mean just start with 300mg of acid in the first place... in which case I understand.

 

[JamesW]

Just put a drop of acid on a pile of the scale to see if it bubbles.

 

[voidpointer]

Just put a drop of acid on a pile of the scale to see if it bubbles.

Just did this and yep it bubbled/fizzed right away and then completely disappeared.

 

[voidpointer]

This is from a different thread started in Jan, but I had some difficulties with my CH test and so another member suggested a different approach to the test involving dilution with distilled water. I posted the results here, but my CH came out to 950ppm which is a wildly higher number than I'm used to, so I suspect it's wrong. But since it may play a part with the crystals here, I did want to share the information.

 

[JamesW]

950 will certainly cause some issues.

What is the CSI at 950 CH?