Hot Tub Filled With Soft Water.. Ch Will Not Increase!

[SiriusPwr]

Second year with the tub and constantly learning so I'm still fairly new at this.

I'm on well water with very high iron so i had potable water trucked in. I added prevent 2 (Sequestering agent) while the tub was being filled. The next day i realized that the water trucked in was soft water after checking with my Lamotte colour Q7 digital tester. it was showing 30ppm of calcium hardness. My ALK was at about 60 and PH about 7.8. i added ALK rise and went to 100ppm so i then started to add Cal-rise. First off i got "pool calcium rise" in a 1.7kg container. i was told at the store that its the same stuff for pool and spas. For my 5000L swim spa i was to use 1kg of cal-rise. i did just that, jets on high, waited about hour and tested and only went up 10ppm. waited another 3hours another 10ppm. waited another 3 hours and no change. i dumped the rest in so total of 1.7kg and few more hours went to 60ppm. a day later its still at around 55-65ppm. Today my PH is higher at 8.1ppm so i added some PH reducer. I haven't added any dichlor just yet, i wanted to get my ALK,PH, and CH right before i go any further.

My question is why is the CH not rising up? do i need another 1.7kg ? And by me adding all this Calcium am i greatly increasing my TDS?

[Greenhorn]

Looks to me like you added chemicals that weren't needed. A TA of 60 and pH of 7.8 is darn near perfect. Why did you add the prevent 2 to the water? I have high iron in my well water also, and I just used a pre-filter on the end of the hose when I filled up. My CH was 280 from the well, and my soft water was 10 ppm. I added about 2/3 well water, and the rest soft water. I ended up with a CH of 150. You should test your well water for CH. If you have a higher CH, maybe just drain out half or so and then add water from your well. What is cal-rise? Is it calcium chloride? Does it say on the container? From what I've read on this site, I wouldn't worry about your TDS. You will dump and refill in 3-6 months for a fresh batch of water. Good luck.

[SiriusPwr]

i'd like to see TA of a 100 and PH of 7.4 and a CH of 150-250.

Going by the manual of the H2X swim spa it said to add prevent 2 only when fully refilling the tub.

The iron in my well is extremely high (don't have numbers off hand but eyes bulged when i told water specialists) I have to take apart my house jet pump once a year and flush it out. the amount of iron sludge that comes out is insane.

My water goes through 6 stages of filtration before hitting my taps and still a tiny bit of iron trickles through. this afternoon i just made a bypass in my water system that will allow me to fill the tub just before my water gets softened, it will have a CH of 125 after going through 5 stages and insignificant amounts of iron. Saves me $100 not having to call the water truck. Its just nerve racking not to know why my CH level is not increasing... I've now put double the amount specified and only increased 25-30ppm. Yes, cal-rise is calcium chloride. Its good to know that it won't be affecting my TDS within the 6 months. My ALk is now 105 and my PH is 7.5 I'm adding my dichlor , the hell with the CH level.

[SiriusPwr]

doing more research on this Prevent 2 Sequestering agent, manual and bottle says it prevents staining and scaling on heaters and plumbing.

when i look further into it, it says these compounds combine with metal ions, like Calcium, to substantially inactivate the ion. So by me adding the sequestering agent at the beginning kept breaking down the calcium added. gotta treat chemicals like food ingredients, Less is better. Can't wait till next fill up, 3rd time is a charm..

Thx Greenhorn for questioning the use of the prevent 2.

[chem geek]

i'd like to see TA of a 100 and PH of 7.4 and a CH of 150-250.

You shouldn't have the CH much above 150 if you're planning on having the TA at 100. The reason is that the saturation index with this combination at 104ºF is already at -0.16 while at 250 ppm CH it would be at +0.05 and with the heat exchanger surface being roughly 30ºF hotter, the saturation index would be +0.05 to +0.26 so scaling could occur.

Usually 150 ppm CH is enough to prevent foaming which is the only real reason to have any CH in the first place. You could alternatively use magnesium salts (such as epsom salt which is magnesium sulfate or you can get magnesium chloride if you prefer) instead of calcium for this purpose and they won't have any risk of scaling.

Usually 100 ppm TA will be too high for a spa and will have the pH tend to rise. Even with net acidic sources of disinfection such as bromine tabs or dichlor a TA of 80 ppm is usually sufficient (with hypochlorite sources of chlorine one needs a lower TA than that and supplemental pH buffering such as 50 ppm borates).

[PreservedSwine]

Soft water is fine in an acrylic spa- What are you gaining by increasing the hardness to 150-2500ppm? As chem geek mentioned- only benefit (in an acrylic spa) is less foam, rarely an issue unless you're using a bigauinaide as a sanitizer) The sequestering agents will cause more harm than good if you're adding Calcium into the water- it will likely scale on the element

[Greenhorn]

I've read that soft water with no CH would attack your pumps. You need CH in your water.

[PreservedSwine]

 

I've read that soft water with no CH would attack your pumps. You need CH in your water.

Softened water is not corrosive(assuming the PH is neutral). Naturally occurring soft water typically is. I believe it's this correlation that leads to poor advice somewhere down the line... You'll still hear at many local shops that softened water is corrosive, and you need the calcium to somehow make it less corrosive. This is simply untrue.

Here's some reasons for the popular myth that softened water is corrosive

http://www.how-to-purify-water.com/water-myths.html

[Greenhorn]

Thanks, preserved swine. I stand corrected. I read that info in some literature from a dealer. So, using these numbers, pH 7.6, TA 60, CH 10, temp. 102, 50ppm borates, I get a CSI of -1.23. Is this OK for my Jacuzzi Hot Tub?

preservedswine: pork hocks?

[PreservedSwine]

That seems fine to me, but I'm hopeful chem geek chimes in. The more I've learned about water chemistry, the more I realized there's more too it than I previously thought

PreseredSwine was a WWII figher plane my Grandfather flew. A self proclaimed drunken pig, but with class

[chem geek]

You don't need CH to prevent metal corrosion (see this link for a discussion about LSI and metal corrosion). So long as you have no plaster or grout in between tile or other surface that contains calcium carbonate, then you do not need calcium in the water. However, you might consider using 120-150 ppm CH to prevent foaming. Technically you could use magnesium instead of calcium for that purpose but magnesium chloride is harder to find though magnesium sulfate (epsom salt) isn't hard to get. It's just easier to use calcium since you can measure that anyway.

[Greenhorn]

Once again, thank you sir.