Taylor CH, Salt tests and Magnesium Chloride

[mgtfp]

That's quite interesting, I like the idea of this Red Sea CH test. Looks more fiddly, but it also offers a 5ppm accuracy. Seems to cost about 65AUD for 75 tests. That's actually alright. The CCL test gives me 70 tests with 25ppm accuracy for 40AUD. You could probably reduce the sample size from 5ml to 2.5ml and get 150 tests out of the Red Sea kit with 10ppm accuracy (5ppm might be required for fish, but 10ppm should definitely be enough for a pool). I also like the idea of the more quantitative titration, not having to rely on reproducible drop size. And you won't have a problem with Mg contamination (which I don't think I have, but who knows what the previous house owner has put into the pool...).

I saw that Red Sea also offers a test to measure Carbonate Alkalinity (CA), not Total Alkalinity (TA). I was wondering if that could offer an indirect method to test for CYA. If you tested both, CA and TA, and know your FC and pH, then you should be able to calculate CYA by using chemgeek's Pool Equations. When using the simplified formula for CA that's behind PoolMath, then you wouldn't even need FC and pH. I would love to get rid of the dreaded black-dot test and replace it with a quantifiable titration.

 

[JoyfulNoise]

Their carbonate alkalinity test is basically the same test as the Taylor test. When CYA and bicarbonate are both present, they add to there alkalinity over the same pH range and so you get a Total of the two. If you were to use the Red Sea dKH test, you'd get the same value as the Taylor TA test. The Red Sea test can't distinguish CYA from bicarbonate. In a reef tank, one would only expect carbonate and bicarbonate alkalinity with a pH roughly above 8.2 . Thus you first titrate the carbonate alkalinity using phenolphthalein indicator and then you add methyl orange or another suitable mixed indicator (like the Taylor indicator) and you then titrate all of the bicarbonate alkalinity. Depending on the volumes and normality of the titrant used, there are simple formulas to determine the concentrations of carbonate and bicarbonate. One would never find cyanuric acid in a reef tank, nor any other significant alkaline species (such as borates or phosphates...although once could correct for phosphates as it would build up from large concentrations of spent food or metabolic waste).

 

[mgtfp]

Thanks for the explanation, Matt. That makes sense. If you don't expect any CYA or other TA contributers in your fish tank, just call your TA test a CA test, and don't confuse aquarium owners that will probably never have heard about CYA.

Would have been too good to be true...

 

[Pklambooy]

If you add magnesium chloride to your pool, it adds chloride to the water and that is what the Taylor “salt” test measures. There is no way to tell the difference between sodium chloride, potassium chloride or magnesium chloride. They all add chloride. Magnesium chloride is MgCl₂ so on a molar basis it adds twice as much chloride as sodium chloride does.

Depends on how you add since formula weights of the two salts are different. If you add equal masses of both salts you'd only be adding about 20% more moles of chloride using magnesium chloride.

 

[Pklambooy]

oh, right. thanks

 

[Captain Max]

OK Red Sea Ca kit seems to work perfectly. Fill water, pool water and a 200ppm standard all show expected results. I also added Calcium Chloride to the pool to up my (now confirmed) low CH levels, and the Red Sea kit showed the expected amount of increase in CH levels 24 hours later.

The test itself is pretty fiddly to use compared to the Taylor test, but not too bad considering CH doesn't need to be tested frequently. Also need to remember to multiply the results by 2.5 to get CH as Caco3, as the test result is in ppm Ca ions.

So any other Aussies out there who are using a magnesium salt blend, this is the answer to CH testing.

Just wanted to say thanks for the info provided in this thread. Another Aussie here with a majority of Magnesium salts - I ordered the Red Sea CA kit, and now have the info I need. Much appreciated!

I do have a question that I'm hoping someone may be able to provide some thoughts on....

My CH level is quite low (100 - using Red Sea kit above, after multiplying result by 2.5). Pool is fibreglass with SWG, and according to TFP 100 is well below the recommended level. However, my pool manufacturer recommends CH between 80 to 120ppm (and basically says there should be no reason to add Calcium Chloride to my water). Is there any reason I would want to increase the hardness to the TFP recommended levels? Or downsides to keeping it at its current level?

 

[mgtfp]

Just wanted to say thanks for the info provided in this thread. Another Aussie here with a majority of Magnesium salts - I ordered the Red Sea CA kit, and now have the info I need. Much appreciated!

I do have a question that I'm hoping someone may be able to provide some thoughts on....

My CH level is quite low (100 - using Red Sea kit above, after multiplying result by 2.5). Pool is fibreglass with SWG, and according to TFP 100 is well below the recommended level. However, my pool manufacturer recommends CH between 80 to 120ppm (and basically says there should be no reason to add Calcium Chloride to my water). Is there any reason I would want to increase the hardness to the TFP recommended levels? Or downsides to keeping it at its current level?

My understanding is that some older FG pools like higher CH to avoid staining. If your pool manufacturer recommends 80-120ppm, then I'd go with that.

@Texas Splash has more experience with FG pools, maybe he can shed more light on the - I think - relatively high TFP recommendation for CH in FG pools

 

[Texas Splash]

my pool manufacturer recommends CH between 80 to 120ppm (and basically says there should be no reason to add Calcium Chloride to my water

That is a reasonable CH level. I suspect it was not recommended so much as to protect against gelcoat erosion like a low CH would apply for plaster, but more for stain control. Our TFP minimum of 250 was assigned more for the "all other" pool scenarios where we don't know if a FG owner may have a waterline tile or heater that specifically calls for more CH.

 

[Captain Max]

That is a reasonable CH level. I suspect it was not recommended so much as to protect against gelcoat erosion like a low CH would apply for plaster, but more for stain control. Our TFP minimum of 250 was assigned more for the "all other" pool scenarios where we don't know if a FG owner may have a waterline tile or heater that specifically calls for more CH.

Thanks for the replies above.

Wasn't sure how much to trust the Manufacturer recommended levels, but it sounds like they shouldn't be a problem in this case for CH (and I'm guessing likely not an issue if they creep a little higher over time).

A little off topic I know, but the pool manufacturer recommended levels for other key measurements also differ quite significantly from TFP guidelines. eg. PH 7.2 - 7.4, TA 80 - 120, CYA 30 - 50, Chlorine 1 - 2. Any good reasons I should be following these targets ahead of TFP?

 

[mgtfp]

PH 7.2 - 7.4, TA 80 - 120, CYA 30 - 50, Chlorine 1 - 2

You won't have much fun with these targets.

The relatively high TA means that the water is very oversaturated with dissolved CO2 which wants to outgas the faster the lower the pH is. pH rises in the process, like bubbly water tasting less acidic when the bubbles bubble out.

With a TA around 70 or lower you'll find pH to be quite stable in the higher 7-range.

FC 1-2 will sooner or later result in algae, even in the lower (for a SWG) CYA-range of 30-50.

In Melbourne, CYA around 70 works well for me with a SWG in mid summer. At the moment I let it go down with the frequent draining due to the winter rains.

In spring, start with CYA around 60 and see how you go. Follow the recommended FC/CYA Levels.

 

[Captain Max]

You won't have much fun with these targets.

The relatively high TA means that the water is very oversaturated with dissolved CO2 which wants to outgas the faster the lower the pH is. pH rises in the process, like bubbly water tasting less acidic when the bubbles bubble out.

With a TA around 70 or lower you'll find pH to be quite stable in the higher 7-range.

FC 1-2 will sooner or later result in algae, even in the lower (for a SWG) CYA-range of 30-50.

In Melbourne, CYA around 70 works well for me with a SWG in mid summer. At the moment I let it go down with the frequent draining due to the winter rains.

In spring, start with CYA around 60 and see how you go. Follow the recommended FC/CYA Levels.

Yeah, I found I was constantly adding buffer to get the TA up, which was being brought down quickly with the low pH (auto acid doser). Happy to move away from those targets (have now set pH target to 7.7, and TA is at 70).

As for CYA, the pool was initially setup by the installer, and levels were around 80 at the start of summer, and have gradually reduced to about 40 now (similar to you, I'm ok for that to be on the low side at the moment in Melbourne). Chlorine I've actually struggled to get it down to the 1-2 level anyway. Normally more like 5 to 10 (although I've only recently got a good home test kit, so not sure how reliable the data was previous to that). Pool has always looked great at least.

Thanks again for the feedback.

 

[AUSpool]

Stay off the magnesium gravy train everyone. The fancy magnesium day spa salts are 10X the price and have 30% more impurities, iron being one Of them.

And if you’ve ever wondered why it’s common for water to turn green when it is added this is a pic of the drying ponds where it comes from, southern end of the dead sea.

798282C2-1D23-44C9-A86C-4722551048D7.jpeg

• AUSpool
• May 26, 2023

 

[Captain Max]

Stay off the magnesium gravy train everyone. The fancy magnesium day spa salts are 10X the price and have 30% more impurities, iron being one Of them.

And if you’ve ever wondered why it’s common for water to turn green when it is added this is a pic of the drying ponds where it comes from, southern end of the dead sea.

798282C2-1D23-44C9-A86C-4722551048D7.jpeg

• AUSpool
• May 26, 2023

I'm very inexperienced with pools (first time owner of one for about 7 months now), but I haven't experienced any issues so far. Being a small pool, the salt cost is fairly insignificant for me (especially when compared with what it cost to have the pool installed!).

I was convinced to go this way by both the installer and a friend who recently had a pool installed, main reason being that one of my kids has eczema, and the water is supposed to be much better on his skin. He didn't have any skin issues last summer after spending almost every day swimming (although who knows if he would have with a regular salt pool?).

I also haven't seen any side effects due to the impurities. Water clarity is excellent.

I guess I could gradually switch back to regular salt over time (if I wanted), by just adding normal salt instead of mineral salts right?

 

[AUSpool]

I'm very inexperienced with pools (first time owner of one for about 7 months now), but I haven't experienced any issues so far. Being a small pool, the salt cost is fairly insignificant for me (especially when compared with what it cost to have the pool installed!).

I was convinced to go this way by both the installer and a friend who recently had a pool installed, main reason being that one of my kids has eczema, and the water is supposed to be much better on his skin. He didn't have any skin issues last summer after spending almost every day swimming (although who knows if he would have with a regular salt pool?).

I also haven't seen any side effects due to the impurities. Water clarity is excellent.

I guess I could gradually switch back to regular salt over time (if I wanted), by just adding normal salt instead of mineral salts right?

Geday Max and and welcome to TFP,
your pool looks great, I love that honed concrete and at 18,000L it‘s very similar to mine in size. Your water clarity is excellent, I had to look twice to see if there was water in it.

The main problem that could present from the impurities is iron staining. Regular salt is 99.4%, the good mag salts are 98% while the cheap ones are only 95% pure.

Regular salt with a pool managed the TFP way will be just as good for skin conditions as the mag salts, our son has a history of skin issues and the pool has been great for him.

You can easily just add regular salt as required. Be cautious of the super fine which has a cyanide based anti caking agent in it. It’s probably fine in such small amounts but I would rather not have it in my pool.

One of the the things that I dislike about the mag salt craze is the glossy advertising. The industry, driven by the large supply company’s, are not interested in us, our pools, or our welfare, they just want our money. They say it’s like the Dead Sea experience, it’s nothing like the Dead Sea, the Dead Sea is 10X more saline, salty, than the ocean. They haven’t established an ideal maximum level and I am unaware of any public health assessments of high Mg concentrations. They dont have a good handle on testing at the elevated levels, the spin test will give a total hardness result but it is above it’s range. Magnesium is not included or mentioned in the current (but old) Australian Standard for private pool water quality, AS 3633.

 

[Captain Max]

Geday Max and and welcome to TFP,
your pool looks great, I love that honed concrete and at 18,000L it‘s very similar to mine in size. Your water clarity is excellent, I had to look twice to see if there was water in it.

The main problem that could present from the impurities is iron staining. Regular salt is 99.4%, the good mag salts are 98% while the cheap ones are only 95% pure.

Regular salt with a pool managed the TFP way will be just as good for skin conditions as the mag salts, our son has a history of skin issues and the pool has been great for him.

You can easily just add regular salt as required. Be cautious of the super fine which has a cyanide based anti caking agent in it. It’s probably fine in such small amounts but I would rather not have it in my pool.

One of the the things that I dislike about the mag salt craze is the glossy advertising. The industry, driven by the large supply company’s, are not interested in us, our pools, or our welfare, they just want our money. They say it’s like the Dead Sea experience, it’s nothing like the Dead Sea, the Dead Sea is 10X more saline, salty, than the ocean. They haven’t established an ideal maximum level and I am unaware of any public health assessments of high Mg concentrations. They dont have a good handle on testing at the elevated levels, the spin test will give a total hardness result but it is above it’s range. Magnesium is not included or mentioned in the current (but old) Australian Standard for private pool water quality, AS 3633.

Thanks, yep we are in love with how the concrete turned out. Also stays nice and cool in summer which is a plus.

And yes, water is beautiful. My 5yo son actually asked me a couple of weeks ago why I emptied all of the water out

The water does feel great on the skin, but I have no idea how different it would feel with regular salt. I certainly understand the salt levels are nowhere near that of the dead sea, let alone the ocean. I still have a few full bags of the mineral salt though, so will probably keep going with it for now, but may reconsider once that runs out. Haven't had any staining issues, but I'll keep an eye out for that.

Cheers.