I've been using the dichlor/bleach method in my spa for about 3 months (CYA ~35 ppm). I've generally been diligent with the bleach (using Walmart "Great Value" 6%), but there have been a few times where I forgot for a few days and the FC got very low, possibly down to 0. Whenever this occurred I immediately added more FC to the tub, but only slightly more than the regular amount-- 3-4 oz. (I would typically add 2 oz on an off day, which is ~5ppm FC for my 260 gallon tub)
In the last few weeks, I've noticed an odor has developed that seems to be resistant to normal sanitation methods. It's not trichloramine, which I recognize. Instead it's an almost rancid smell. You can't smell it when you're in the tub, but you can smell it once most of the water evaporates off the body after a soak. If I dip my hand in the water and let it dry for about a minute, the odor is quite noticeable. This odor has persisted despite my keeping an FC of >2ppm at all times in the water for the past several weeks.
Has anybody dealt with this problem before? What is this odor and is there any way to get rid of it short of a refill? My leading hypothesis is that these are oxidation-resistant bacterial byproducts that were formed during the aforementioned periods of low FC. The pinned dichlor/bleach post says:
So perhaps bacteria multiplied very quickly over a few days and generated a lot of nasty chemical waste.
More generally, is there some way to safely restore spa water that has sat at low FC for an extended period? If so, how much sanitizer is needed? And if not, why not? If you can sanitize creek water for drinking with chlorine tablets, I would think one would be able to sanitize spa water for soaking.
In the last few weeks, I've noticed an odor has developed that seems to be resistant to normal sanitation methods. It's not trichloramine, which I recognize. Instead it's an almost rancid smell. You can't smell it when you're in the tub, but you can smell it once most of the water evaporates off the body after a soak. If I dip my hand in the water and let it dry for about a minute, the odor is quite noticeable. This odor has persisted despite my keeping an FC of >2ppm at all times in the water for the past several weeks.
Has anybody dealt with this problem before? What is this odor and is there any way to get rid of it short of a refill? My leading hypothesis is that these are oxidation-resistant bacterial byproducts that were formed during the aforementioned periods of low FC. The pinned dichlor/bleach post says:
So perhaps bacteria multiplied very quickly over a few days and generated a lot of nasty chemical waste.
More generally, is there some way to safely restore spa water that has sat at low FC for an extended period? If so, how much sanitizer is needed? And if not, why not? If you can sanitize creek water for drinking with chlorine tablets, I would think one would be able to sanitize spa water for soaking.
