New Hot Tub!

[pinguy]

Just got this little hot tub, only 150 gallons!

I read through the Bromine guide and I think I want to go that route. We had a hot tub in the past and never did anything except throw bromine tabs in.

I was thinking I'd get a tab floater, and just do that along with start up powdered bromine. That seems like that's all there is to it, or am I missing something? I'll balance the other chemicals of course.

They also sent these things with the Tub, what are they and why should I throw them out?

 

[pinguy]

Ok so I re-read the sticky and the orange bottle is MPS. I can use it instead of chlorine to shock, am I reading that correctly?

 

[siska]

Sorry, don't know anything about bromine tubs :-(

 

[pooldv]

Congrats on the new tub. Yes, that is mps that you can use to shock. I don't know a thing about that silver stuff. Except that I don't have any of it in my hot tub!

 

[chem geek]

The silver in combination with MPS is used in the Nature² system as an EPA-approved disinfectant and I noticed the Nature² logo on the silver product so I presume that is EPA-approved.

However, that system doesn't use bromine, but normally uses chlorine "as needed" so usually once a week or two to keep the water clear.

So you need to decide whether you want to use the Nature² with MPS system for the chemicals shown in the photo or whether you want to go with bromine tabs. Those are really two different systems. Since you have the Nature² silver with MPS, why don't you go with that unless you've already added sodium bromide for a bromide bank.

 

[pinguy]

The silver in combination with MPS is used in the Nature² system as an EPA-approved disinfectant and I noticed the Nature² logo on the silver product so I presume that is EPA-approved.

However, that system doesn't use bromine, but normally uses chlorine "as needed" so usually once a week or two to keep the water clear.

So you need to decide whether you want to use the Nature² with MPS system for the chemicals shown in the photo or whether you want to go with bromine tabs. Those are really two different systems. Since you have the Nature² silver with MPS, why don't you go with that unless you've already added sodium bromide for a bromide bank.

Thank you!! When I saw the nature 2 I assumed it was an unneeded mineral cartridge like their pool products.

I read the manual for the silver system, and it says to dose weekly with dichlor or MPS. Is there any reason to use one or the other?

 

[JoyfulNoise]

Any reason why you wouldn't just use the dichlor-then-bleach method? Seems to me that any other method (bromine, silver, etc), is just going to cost you more money in the long run. I imagine the Nature2 silver stuff isn't cheap.

Also, wouldn't it be a bad idea to use dichlor (chlorine) and silver together? Would the silver react and form silver chloride which is mostly insoluble in water? That's a reason to choose MPS over dichlor in my guesstimating.


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[pinguy]

Any reason why you wouldn't just use the dichlor-then-bleach method? Seems to me that any other method (bromine, silver, etc), is just going to cost you more money in the long run. I imagine the Nature2 silver stuff isn't cheap.

I'm lazy and looking for the method of least daily maintenance. The nature2 silver catridges are $30 every 4 months. Definitely more expensive than chlorine only, but not terrible.

Also, wouldn't it be a bad idea to use dichlor (chlorine) and silver together? Would the silver react and form silver chloride which is mostly insoluble in water? That's a reason to choose MPS over dichlor in my guesstimating.

The manual says dichlor is fine, but tri-chlor is a no no. It's my understanding that the silver needs some sort of oxidizer to be effective, either MPS or chlorine.

 

[JoyfulNoise]

I'm lazy and looking for the method of least daily maintenance. The nature2 silver catridges are $30 every 4 months. Definitely more expensive than chlorine only, but not terrible.

Hahaha....brutal honesty, I love it!!

The manual says dichlor is fine, but tri-chlor is a no no. It's my understanding that the silver needs some sort of oxidizer to be effective, either MPS or chlorine.

hmmmmm, well trichlor is much more acidic than dichlor and adds more salt than dichlor so perhaps there is something to that.


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[JoyfulNoise]

Well, it would seem that, rather than poking around in the dark, one should simply go to the source of all good pool & spa knowledge - John A. Wojtowicz.

This JSPSI Paper should be required reading for all pool nerds....

It would seem that using MPS with Ag+ ions produces both sulfate radicals (SO₄^-●) and divalent silver (Ag⁺⁺) both of which are powerful oxidizers (see page 132 of the paper).

 

[chem geek]

Yes, the paper you found explains why the silver + MPS system works to be able to pass the EPA tests, specifically with the Nature² product. That is why it is EPA approved and why I suggested it would be OK to use since he already has it. I have referred to this in many posts such as this one that refers to this post where I quote from that paper.

As for chlorine producing silver chloride, it doesn't precipitate in the spa because 1) the silver is added slowly by chlorine oxidizing the silver and 2) any formation of silver chloride on the silver cartridge is self-limiting in that it is slightly soluble. This is intentional because the solubility of silver ions into the spa water will be limited by the solubility of silver chloride. That's how the system regulates the amount of silver and is also why the silver won't stain spa surfaces. Silver chloride forms silver chloride ion pairs (e.g. AgCl⁰, AgCl₂^-, AgCl₃^2-, AgCl₄^3- as described in the paper Thermodynamic Properties of Chloro-Complexes of Silver Chloride in Aqueous Solution). The net result is that the silver ion concentration initially drops and then rises again as a function of chloride ion concentration as I show in the table below.

ppm Salt .. ppb Ag⁺ & AgCl_n^1-n
....... 1 ........ 1167
....... 2 .......... 600
....... 5 .......... 260 ... 8 ppm FC results in 5 ppm chloride
..... 10 .......... 147 ... low chloride level in tap water
..... 20 ............ 91
..... 50 ............ 58
... 100 ............ 49
... 250 ............ 49 ... EPA recommended limit for drinking water
... 500 ............ 59
. 1000 ............ 81
. 2000 .......... 129
. 3000 .......... 179 ... saltwater chlorine generators in U.S.
. 5000 .......... 281 ... saltwater chlorine generators in Australia
10000 .......... 561
20000 ........ 1217
35000 ........ 2445 ... ocean levels of salt

Since most tap water has at least some chloride salt in it and since using chlorine will build up chloride, the silver ion concentration is naturally limited.

 

[Isaac-1]

I just wanted to say hi, and welcome. If you go with the Hot Spring Freshwater "Nature 2" cartridges that you can't use the cheaper Nature 2 branded cartridges, you must use the special Hot Spring cartridges as they have an extra lip ridge on the holder, placing a Nature 2 branded cartridge in a Hot Spring filter holder will fall right through and block water flow. I bought some off ebay cheap a while back that were advertised as for Hot Spring tubs, and turned out to be the generic Nature 2 cartridges, and had to re-engineer the extra tab with a zip tie to make them work.

Ike