Hi there
We have a fibreglass lined wood-burning hot tub (Approx 1000L), and it will be used in a holiday rental. As such, our laws (UK) say it must be emptied and refilled after each rental, which is usually 3-7 days. We opted for a wood-burner as they heat up in 2 hours, and we can leave the guests in control of when they want it warmed up.
So my challenge is getting the water chemistry right. Traditionally with wood-burning tubs, you don't need chemicals as the water only stays in 3 days. However, by law we must add Chlorine due to it being used by other guests.
I've been reading the guides and advice, but my problem is a lot of them require you to do things quite slowly. We will be filling up the tub in the morning, and have until mid-afternoon when guests arrive, so not a huge amount of time to get things right. I will then be checking the water levels each morning and adjusting where possible. I'll be using Chlorine granules, but was advised a floating tablet might be good to leave in overnight after it's been used to keep the levels a bit more consistent, as we can't ask the guests to add Chlorine when they get out and want to avoid it being zero for an extended period.
Now my thoughts were that the chemicals needed should be fairly consistent each time we fill it up from empty, so after a while we'll know what to dose up, then test and fine-tune if needs be... However I'm not quite at that point yet!
So here's my first attempt, would be amazing for some feedback (I'm using AquaChek digital meter which reads their test strips):
22/3 9am:
2.0 Cl, 6.9 pH, 040 TA
Added 50g Total Alkalinity+. Added 2x20g tablets in a floating dispenser, open partially.
18:00 :
4.2 Cl, 6.7 pH, 090 TA
Happy with the TA, so added 5g of pH+. Chlorine a bit higher than expected, so removed floating dispenser
Hot tub was used by 1 person that evening. Floating dispenser returned to water overnight
23/3 9:20am:
6.0 Cl, 7.4 pH, 000 TA
Alkalinity has dropped right down. Chlorine too high. Removed Cl dispenser completely from water. Added 50g TA+
23/3 12:00: 4.3 Cl, 7.7 pH, 040 TA
TA still low, so added 25g TA+. Dispenser still removed from water.
23/3 19:05 7.7 Cl, 7.4 pH 040 TA.
Planning to add more TA+, then presumably will need to pH- a little bit once TA is correct. Why is Chlorine so high? Why did TA not rise?
Things were following my plan yesterday roughly, apart from the Chlorine dispensing a bit too quickly. I was surprised the TA dropped right down this morning, then didn't rise after adding 25g TA+ but I'm thinking that it's been buffering the pH and so more is needed? Also confused why the Chlorine jumped from 4.3 to 7.7 even when there had been no tablet in since 9am - what could cause this? The hot tub has bubbles (turned off) but no filter, the water gets circulated by the wood burning stove, but we've not heated it since last night (Temp gone from approx 40c to 27c) during the day.
Any tips or advice would be very welcome!
We have a fibreglass lined wood-burning hot tub (Approx 1000L), and it will be used in a holiday rental. As such, our laws (UK) say it must be emptied and refilled after each rental, which is usually 3-7 days. We opted for a wood-burner as they heat up in 2 hours, and we can leave the guests in control of when they want it warmed up.
So my challenge is getting the water chemistry right. Traditionally with wood-burning tubs, you don't need chemicals as the water only stays in 3 days. However, by law we must add Chlorine due to it being used by other guests.
I've been reading the guides and advice, but my problem is a lot of them require you to do things quite slowly. We will be filling up the tub in the morning, and have until mid-afternoon when guests arrive, so not a huge amount of time to get things right. I will then be checking the water levels each morning and adjusting where possible. I'll be using Chlorine granules, but was advised a floating tablet might be good to leave in overnight after it's been used to keep the levels a bit more consistent, as we can't ask the guests to add Chlorine when they get out and want to avoid it being zero for an extended period.
Now my thoughts were that the chemicals needed should be fairly consistent each time we fill it up from empty, so after a while we'll know what to dose up, then test and fine-tune if needs be... However I'm not quite at that point yet!
So here's my first attempt, would be amazing for some feedback (I'm using AquaChek digital meter which reads their test strips):
22/3 9am:
2.0 Cl, 6.9 pH, 040 TA
Added 50g Total Alkalinity+. Added 2x20g tablets in a floating dispenser, open partially.
18:00 :
4.2 Cl, 6.7 pH, 090 TA
Happy with the TA, so added 5g of pH+. Chlorine a bit higher than expected, so removed floating dispenser
Hot tub was used by 1 person that evening. Floating dispenser returned to water overnight
23/3 9:20am:
6.0 Cl, 7.4 pH, 000 TA
Alkalinity has dropped right down. Chlorine too high. Removed Cl dispenser completely from water. Added 50g TA+
23/3 12:00: 4.3 Cl, 7.7 pH, 040 TA
TA still low, so added 25g TA+. Dispenser still removed from water.
23/3 19:05 7.7 Cl, 7.4 pH 040 TA.
Planning to add more TA+, then presumably will need to pH- a little bit once TA is correct. Why is Chlorine so high? Why did TA not rise?
Things were following my plan yesterday roughly, apart from the Chlorine dispensing a bit too quickly. I was surprised the TA dropped right down this morning, then didn't rise after adding 25g TA+ but I'm thinking that it's been buffering the pH and so more is needed? Also confused why the Chlorine jumped from 4.3 to 7.7 even when there had been no tablet in since 9am - what could cause this? The hot tub has bubbles (turned off) but no filter, the water gets circulated by the wood burning stove, but we've not heated it since last night (Temp gone from approx 40c to 27c) during the day.
Any tips or advice would be very welcome!
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