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Hi

I’m new to owning a hot tub and have recently Drained and refilled my hot tub and managed to balance the water using Nitros approach but by the time I have got the pH under 7.8 and stable the TA had dropped to 35ppm.

35ppm seemed low even though using a online calculator the water was balanced with a score of around 0.09.

The Calcium (hardness) is at 251ppm.

I tried to raise the TA to around 80 yesterday by adding 70g of Sodium Bicarbonate after dissolving it in water from the hot tub and adding it slowly.  The TA went up to 76ppm.

That was now 16 hours ago and retesting This morning the pH has jumped to 8.15 from around 7.5.

I was under the impression that Sodium Bicarbonate wouldn’t raise the pH significantly, is that incorrect.

Trying to balance the water to have a TA that is over 50ppm and a pH around 7.6 Or lower is seeming a real struggle.

Can anyone provide some help with what I’m doing wrong?

This morning I have now added another 70g of pH minus in small amounts while running the jets/air constantly, but pH is still rising above 7.8.

The hot tub was filled with mains water via a water softener and then I raised the calcium levels by adding Calcium Chloride.  I then followed Nitros post and started all the jets and air and basically kept adding pH minus until it didn’t rise above 7.8 after aerating for an hour, took all day on Sunday :(

I’m testing using an Exact iDip 570nm photometer and also using a fully calibrated pH meter, Apera PC60, so I’m fairly confident the readings are correct.

Any help/advice would be really helpful.

Thanks

Rob

TEST RESULTS

TA 48ppm

Calcium Hardness 241ppm

Total Hardness 72

pH 7.96

Temperature 39C

Phosphate Reading is HIGH

Bromine 4.15

Hot Tub Size 1200 litres 

Water appearance: Slightly milky after adding the Sodium Bicarbonate yesterday.

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Balanced water is the goal. Ph up to 7.8 is fine. Ph and alkalinity are linked and cannot be separately adjusted. Ph is a logarithmic scale while alkalinity is a ppm, so the amount of change from a chemical varies with what the readings are to start. Keep it balanced with ph 7.8 or less and you will be fine, don't worry about alkalinity if you can't get it where you want it. 

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On 7/15/2020 at 5:18 PM, RDspaguy said:

Balanced water is the goal. Ph up to 7.8 is fine. Ph and alkalinity are linked and cannot be separately adjusted. Ph is a logarithmic scale while alkalinity is a ppm, so the amount of change from a chemical varies with what the readings are to start. Keep it balanced with ph 7.8 or less and you will be fine, don't worry about alkalinity if you can't get it where you want it. 

Thanks for the reply, reassures me that I wasn’t doing something wrong.

 

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