My 1st spa...some questions

[david426]

Hi everyone,

I've never owned or maintained a pool or spa and I'm having one delivered next week. I've been researching for weeks and have settled here. I appreciate this website as I also want to use a minimalist approach. I've received my k-2006 and read the waterproof book. My plan is to use bleach and ozone after the water is balanced.

Question one: Is CYA required? I don't have an issue with daily dosing of bleach.
My spa will be in total shade all the time, shaded by the house; also covered of course when not in use. If I can get away with one less compound, I'll do it.

Question two: Is MPS required? I upgraded to a bigger ozonator. Is it possible to maintain low CC with bleach and ozone alone?

Question three: What advice do you have for one who does not wish to use borate?

Thank you

 

[chem geek]

Welcome to TFP!

Yes, CYA is required and is most easily added by using Dichlor initially until the CYA builds up to around 30 ppm (though if you wanted to add the small amount of pure CYA to start then you could do that instead -- pure CYA doesn't dissolve very quickly). If you do not have CYA in the water, then the chlorine is too strong and will degrade the hot tub cover faster and not be as pleasant for you as it will oxidize skin and swimsuits faster and will outgas faster.

You should not need to use MPS in a chlorine spa. Proper maintenance usually prevents CC from staying though obviously it forms during the soak and is oxidized in the hours after your soak when you add sufficient levels of chlorine to handle the bather load.

Note that with your ozonator that you most definitely will need to add the chlorine every day or two even when you are not soaking because ozone reacts with chlorine. When there is regular soaking, so significant bather load, then the ozone helps to oxidize the bather waste so the chlorine demand is lower than without ozone, but if you aren't soaking every day or two then in between soaks the ozone is reacting with and using up chlorine usually doubling (or more) the chlorine demand from roughly 25% loss per day to 50%+ loss per day.

If you do not use borates then when using bleach you will have to be more diligent and careful about controlling your pH since it will tend to rise though having the Total Alkalinity (TA) be lower will help somewhat (though the pH will rise a lot when you add the bleach and then drop down as the chlorine is used/consumed). The risk is that of scaling so you'd need to keep your Calcium Hardness (CH) level lower. Why do you wish to not use borates (usually from boric acid)?

 

[david426]

Thanks chem geek,

To answer your question why not use borate; I have no good reason, other than I don't want to use compounds needlessly. The dealer wants to give me a spa frog silver ion cartridge that I don't think I'll use. I suppose I could be convinced to use borate.

Another question: I found germicidal bleach at lowes claiming to be about 91.3 inert and 8.7 sodium hypochlorite code dated a14230 (I think August 2014) is it good to use?

 

[chem geek]

The borates provide additional pH buffering so that the pH doesn't rise as much. This is very important when using bleach because though it is pH neutral when accounting for chlorine usage/consumption, carbon dioxide outgassing from the usual high aeration in a spa would have the pH rise a lot. Dichlor is only pH neutral upon addition but when chlorine is used/consumed the pH drops so between that and the carbon dioxide outgassing the pH tends to remain fairly constant. So I strongly suggest that you use the 50 ppm Borates by the time you switch to using bleach. You can get boric acid from DudaDiesel or The Chemistry Store. You can use PoolMath to calculate dosage.

That germicidal bleach would be OK to use if it weren't as old as August if that is indeed the date. This post shows that 8.25% bleach would be about 6.5% after 4 months if stored at 75ºF. That's not terrible, but you can factor that in to your cost calculations to see if that's better than other sources of bleach or chlorinating liquid you may find.

 

[david426]

Thanks again for all your help chem geek,

Would it be ok to use the borax/acid method to add borate in a spa?

Another question: Should I fill with water that's gone through my water softener (ion exchange) that is filled with salt? I think I'd be better off filling with softened water, then aerating and adding calcium chloride

Soft water: PH 7.0 maybe slightly lower, took 3 drops of base to get to 7.4.
TA 100. CH zero I suppose, test was dark blue from the beginning.

Hard water: PH 7.2 took 2 drops of base to get to 7.4.
TA 95. CH 190

Another question: How long do you leave the cover off after you dose bleach? I don't want to have the color bleed off the cover and stain the shell. I've seen this on other people's tubs.

Thank you

 

[chem geek]

You can use the borax/acid method, but because the pH swings so much and spa volumes are small (so it's easy to overdose) you should split your dosages into one-fourths and add the acid first and then the borax, back and forth. That's why using boric acid is easier, but if you already have borax and acid then certainly you can use it as described.

As for whether you need to soften your water, that depends on the level of your CH in the tap water. If it's much greater than 150 ppm, then yes use softened water. To help prevent foaming in the spa, a CH of 120-150 ppm is recommended. So you can use a mix of softened and unsoftened water to achieve that or use softened water and add calcium chloride. You could very likely live with a CH of 190 ppm if you were careful to not let your pH get very high. If you use the 50 ppm borates, then I think you'll be fine with your unsoftened water at 190 ppm CH. As an example assuming that you have your TA lowered to 50 ppm (that's very important), adding 14 ppm FC of bleach to handle two person-hours of bather load would raise the pH from 7.8 to 8.0 and the saturation index would be near 0 (at 104ºF). We've seen scaling start in spas as low as a saturation index of +0.3 so you should be fine.

You are going to get some hot tub cover degradation regardless, but you can lessen this if you leave the cover off for about an hour after your soak since the bulk of the oxidation of bather waste occurs in the first hour or so after your soak, though it continues on for some time after that mostly complete after 12 hours. If you even left the cover off for 30 minutes that would be better than not leaving it off at all. I'm not sure, however, if the color bleed you are referring to is related to chlorine or chloramine outgassing since it might be something more to do with a lack of color fastness in a moist environment. Usually the hot tub cover degradation associated with chlorine is a combination of fading (oxidation of dyes) and deterioration of the water vapor lock material that prevents water getting into the foam insulation. Having the CYA in the water lessens the amount of chlorine outgassing. You can also reduce it (and water evaporation) more as well as retain heat better in the tub if you use a thin foam cover directly over the water. I've seen some people use these and it helps the main hot tub cover last longer, basically just slowing down evaporation and outgassing.

 

[david426]

Wow, I'm surprised:

Wow, I'm surprised:

It's new so wife and I have been living in it. It had 1 ppm FC at first fill but it was gone before it heated up. I added 1 tsp dichlor before soak and it tested at 1 ppm FC and it was gone when we got out. Added another tsp, and in the morning it was gone. Added another tsp before soak and again after the soak it was gone. After that soak I put in 2 tsp, and in the morning it was gone. Added another tsp, had a soak, didn't actually test it this time but we were in for more than an hour. I thought, "well I'll show it what for" so I put in a tbsp of MPS and 3 tsp of dichlor. Tested at 7 ppm FC and only a trace of CC. I was scratching my head. Left the cover off over night and I'm now at 2 ppm FC.

Is it that previous dichlor additions were being used up oxidizing waste and the combo of MPS and dichlor allowed the dichlor to stick around?

Is the now measureable amount of CYA somehow a factor? I've not tested it but I've only added a total of 9 tsp dichlor.

 

[chem geek]

If you didn't have the ozonator, then every person-hour of soaking in a hot (104ºF) spa would require roughly 3-1/2 teaspoons of Dichlor or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (43% MPS). With an ozonator, you might need only half these amounts or perhaps even less depending on the strength of the ozonator. It sounds like you may not be using enough, however.

Also note that in between soaks the ozone will react with the chlorine so increase daily chlorine demand. So if you soak every day or two, then an ozonator works well but if you soak less frequently then it's a bit of a pain since you have to add chlorine more frequently in between soaks. In that situation, it may be better to use MPS given the silver ions since ozone does not react with MPS. Nevertheless, most people find they need to use chlorine once in a while to keep the water clear since MPS doesn't oxidize everything that chlorine does (ozone should do better, but some people still find they need to use some chlorine once in a while).

MPS will show up in chlorine tests so if you plan to use it regularly then you need to test for it separately either via MPS test strips or by getting the Taylor K-2042 MPS interference remover[/url] so you can measure actual chlorine vs. MPS separately. I suspect what you measured may have been leftover MPS rather than chlorine.

 

[david426]

Update...
Really enjoying the spa, thanks everyone for this site and all the good info.

Is a CH of 40 too low?

PH 8 plus, TA 80, CH 40 after first purge, (ahh-some product) drain, fill, drain and fill again.
Aerate over night.
Used 4/5 soft water, and 1/5 hard.
Put in TBSP Alk down so PH nearer to 7.5 for now.
The CSI is negative, about -.3
Should I raise the CH or am I OK? Thanks