Water Left Standing Still 2 Weeks - Decontaminate?

[SuzyQ442]

Ok so some people may think I'm an idiot for leaving my water standing still for 2 weeks.

Now let's see the explanation:

2 weeks ago, time to drain & refill. So we drained, washed & scrubbed everything with bleach & water, refilled fresh afterwards. Purged the non-existent air from the hoses, as should be done. Test water, only need a little baking soda, so it was added. No bromine in yet. Start the pump: works for 1 min then freezes up. Have been waiting for the repair guy for 2 weeks. Should have new pump sometime this week (so he says).

So I did not add any bromine or bleach at that point, since it is the main pump that died and no circulation (and no filtration) was possible anyways.

My question is: should I go through a full decontamination when the new pump is installed? Is there any chance there may be nasties already growing in there? The tub was obviously not used at all after the refill, since the water was at 67 degrees when I filled, and it's probably lower than that now (weather is getting colder). The water added was regular "tap" water. Should I have added bleach anyways? What about flushing the spa... would that also be required?

The spa is brand new and was only used for 4 months prior to this.

Thanks for your help!

[chem geek]

If the water is clear, you could do a 24-hour disinfectant loss test. Add the disinfectant you would normally use, which sounds like bromine in your case. Then measure the loss over 24 hours with the water at warm/hot temperature you would normally keep it at if you were maintaining it for use. If the loss is significantly more than 25% of the original level, then you should decontaminate. I'm assuming you don't have an ozonator. If you have an ozonator and you are using bromine, then you won't be able to do this loss test.

[SuzyQ442]

Thanks for your reply Chemgeek.

I do in fact have an ozonator. I can't do the loss test because the ozonator will use up the bromine, depleting faster, or because it will keep on reactivating it, keeping the level up? (that's just for my personal knowledge).

Since I can't do the loss test, then I assume I should decon?

If so, I would like to neutralize the chlorine before emptying the tub. Can you tell me in what type of store I could find Hydrogen Peroxide in large quantities to do so? (Hardware? pool store? other?) I know at the pool store they sell chlorine neutralizer, but I think it's sodium thiosulfate and not H2O2. I am under the impression that H2O2 would be a "greener" choice, but then I might by way off base. Which is better?

Thanks for your help!

[chem geek]

The ozonator will keep reactivating the bromine, assuming you've got a sufficiently large bromide bank (i.e. added enough sodium bromide after your last fill). Basically, if you are not using the spa now but you find that the bromine level is being maintained by the ozonator and/or a floating bromine feeder, then you probably don't need to decontaminate.

If you do decide to decontaminate, then you can either use the store's chlorine neutralizer (which is probably sodium thiosulfaste as you wrote), but if you want to use hydrogen peroxide then you would use about 2 teaspoons of 3% hydrogen peroxide in 350 gallons for every 1 ppm bromine (not FC). You can, of course, verify the neutralization with your test kit. Sodium thiosulfate is only "not as green" in that it results in sulfur compounds which can be toxic to fish, but it is likely to get very diluted by the time it reaches any waterway. The choice is up to you.

[waterbear]

A good rule of thumb is if you cannot maintain the sanitizer levels by your normal procedures then you should probably decontaminate. If your sanitizer levels stay where they should with just normal maintenance and amounts added then you have nothing in the water creating a sanitizer demand and consuming it.

[SuzyQ442]

The ozonator will keep reactivating the bromine, assuming you've got a sufficiently large bromide bank (i.e. added enough sodium bromide after your last fill). Basically, if you are not using the spa now but you find that the bromine level is being maintained by the ozonator and/or a floating bromine feeder, then you probably don't need to decontaminate.

I guess I wasn't quite clear before... For the past 2 weeks, there has been only straight water in the tub, no bromine or chlorine - zero. I didn't add it as there wasn't any possibility to have circulation, filtration, etc. The tub has had its breaker off for 2 weeks (and still counting), with just plain municipal water. So now, nothing is being maintained because the main pump is gone.

If you do decide to decontaminate, then you can either use the store's chlorine neutralizer (which is probably sodium thiosulfaste as you wrote), but if you want to use hydrogen peroxide then you would use about 2 teaspoons of 3% hydrogen peroxide in 350 gallons for every 1 ppm bromine (not FC). You can, of course, verify the neutralization with your test kit. Sodium thiosulfate is only "not as green" in that it results in sulfur compounds which can be toxic to fish, but it is likely to get very diluted by the time it reaches any waterway. The choice is up to you.

I was thinking that if I do decontaminate, I'll just use the "straight" procedure as posted in the stickies. Just chlorine (bleach) - no bromine, since the tub has to be emptied out afterwards anyways. I just don't see the point in using the bromine for this, unless I'm missing something...? In that case, can I still use the peroxide?

[chem geek]

Sorry about my misunderstanding. I did realize that you hadn't had any sanitizer in the tub and my comment about maybe not needing to decontaminate was referring to when you get your pump back in shape, heat the water, and then see if it keeps sanitizer reasonably well. That is, it was a forward-looking statement. Obviously, to be on the safe side, you can decontaminate, but if you filled with municipal water (that probably had either chlorine or monochloramine in it) and if you didn't heat up the spa water and you didn't get into that water, then it may not have gone horribly bad especially if it's remained clear and has no smell (doesn't prove it's OK, but also doesn't indicate that there's clearly a problem either).

For decontamination, yes you can use straight bleach for that procedure. And yes, you can use hydrogen peroxide to neutralize it before dumping that water. You basically use the same volume of 3% hydrogen peroxide as the volume of 6% bleach you use for superchlorination.

[SuzyQ442]

Sorry about my misunderstanding. I did realize that you hadn't had any sanitizer in the tub and my comment about maybe not needing to decontaminate was referring to when you get your pump back in shape, heat the water, and then see if it keeps sanitizer reasonably well. That is, it was a forward-looking statement. Obviously, to be on the safe side, you can decontaminate, but if you filled with municipal water (that probably had either chlorine or monochloramine in it) and if you didn't heat up the spa water and you didn't get into that water, then it may not have gone horribly bad especially if it's remained clear and has no smell (doesn't prove it's OK, but also doesn't indicate that there's clearly a problem either).

For decontamination, yes you can use straight bleach for that procedure. And yes, you can use hydrogen peroxide to neutralize it before dumping that water. You basically use the same volume of 3% hydrogen peroxide as the volume of 6% bleach you use for superchlorination.

Great! Thanks for your help!