Anyone have a Hot Tub?

^JP^ · 4 Aug 2021 at 12:06

That's the stuff I was looking at, will get some ordered. Thanks

CaptainRAVE · 4 Aug 2021 at 12:13

^JP^ said:
Anyone in a hard water area use a no scale type product at all?

Our tap water comes out at ~400 TDS so we have an RO drinking water system under the sink and our kettle, pots and pans are like new but there is no way I want to fill up 1700 odd litres with it, would take a week.

Yes, 110ml of anti scale when I add fresh water. Exactly same scenario as you.

@LiE i want a duck dispenser

dale1uk · 4 Aug 2021 at 16:13

You want to keep a decent level of calcium in your water otherwise the water can go out of balance and become corrosive, which can attack any metal components within the tub. Recommended calcium hardness levels are ~200ppm

^JP^ · 5 Aug 2021 at 15:38

I’ll have to get some better test strips that do calcium hardness then.
Anglian Water report says calcium hardness is 379 mg/l which I think is the same as ppm.

CaptainRAVE · 5 Aug 2021 at 16:00

There’s no danger of our water ever having too little calcium. I should probably be adding weekly anti scale.

The clarifier worked really well. Water is still crystal clear.

^JP^ · 5 Aug 2021 at 16:13

Does the anti scale solidify the calcium so it's filtered out?

I've just added 150ml no scale to 1700 Litres, will see how it goes.

b0rn2sk8 · 5 Aug 2021 at 16:25

Just so you know TDS (total dissolved solids) doesn’t measure hardness.

Your water supplier will give you a very accurate reading on their website for your specific supply so you don’t need to worry messing what comes out the tap.

Mine is over 400mg/l or ppm (same thing)

LiE · 5 Aug 2021 at 16:37

b0rn2sk8 said:
Just so you know TDS (total dissolved solids) doesn’t measure hardness.

Your water supplier will give you a very accurate reading on their website for your specific supply so you don’t need to worry messing what comes out the tap.

Mine is over 400mg/l or ppm (same thing)

Anglian Water says:

307 mg/l (or parts per million) :Calcium Carbonate
122.8 mg/l (or parts per million) :Calcium

b0rn2sk8 · 5 Aug 2021 at 16:44

The top measure is normally the one to look at and I think includes a few different things

^JP^ · 5 Aug 2021 at 16:48

On the Anglian Water drinking water report for my NR11 postcode:

Total hardness as Calcium (mg/l) 144.4
Total hardness as Calcium carbonate (mg/l) 361

When I stick my TDS pen in the water it's around 390 from the tap and 5 from my RO tap.

Should I be trying to lower the Hot Tub Calcium level to 200ppm?

I just want to stabilise the pH, Total Alkalinity, etc and also not limescale up the tub like an old kettle in a years time!

dale1uk · 5 Aug 2021 at 19:49

Calcium levels up to 500ppm are acceptable, providing the rest of your water balances it out. Anti scale is designed to dissolve/remove existing scale build up from your system. Adding it to fresh water isn't really helpful if you're not doing a water balance test. With a calcium level between 300-400 just keep your pH around 7.2/7.3 and your alkalinity around 75ppm and your water will be perfectly balanced. There is no need to be adding extra chemicals to try and solve a problem you don't have

Here's an online calculator that you can put your test readings into to see if you water is balanced or not:

https://www.pentairpool.com.au/128/Calculators/Saturation-Index-Calculator

^JP^ · 5 Aug 2021 at 20:32

Brilliant, thank you for advice and link!

LiE · 5 Aug 2021 at 20:35

I think for peace of mind a few ml each week of the scale inhibitor is pretty easy.

CaptainRAVE · 5 Aug 2021 at 21:19

Yes, I might switch to doing that.

dale1uk · 5 Aug 2021 at 21:45

CaptainRAVE said:
Yes, I might switch to doing that.

LiE said:
I think for peace of mind a few ml each week of the scale inhibitor is pretty easy.

What are your other test readings(pH and alkalinity) and what's your calcium levels pre and post treatment? Providing you pH and alkalinity are set to suit then there is genuinely zero benefit from adding any anti scale product on a regular basis. All it will be doing as a routine dose is lowering your LSI/overall water balance results, which if you're not testing could be causing more issues than you're trying to solve by making the water corrosive. If you have naturally high calcium levels in your mains water then as I said above, keep your pH lower, which in turn makes your chlorine more effective, and keep your alkalinity at the lower end of the recommended levels. You want to be adding as little in the way of chemicals as possible, not adding stuff for the sake of it.

LiE · 5 Aug 2021 at 22:00

Thing is, keeping water bang on is tricky at times. PH is about 7.4 and TA is around 100-120 (the test strips don’t give exact numbers). Calcium is as per above.

dale1uk · 5 Aug 2021 at 22:16

LiE said:
Thing is, keeping water bang on is tricky at times. PH is about 7.4 and TA is around 100-120 (the test strips don’t give exact numbers). Calcium is as per above.

You don't need to tell me, I have monthly and quarterly service service contracts where the customers will do zero testing and add no chemicals between my visits and then wonder why the water is never perfect. I spend too many hours in my week balancing water in pools and spas/hot tubs only for them to be completely out of spec a week later due to lazy owners!

With those readings your water is balanced as it is and doesn't require anything extra being put it. What's the pH and alkalinity of your mains water?

CaptainRAVE · 5 Aug 2021 at 22:21

I test and adjust daily where I can, pH is around 7.2-7.6, alkalinity 120-180. Our water supply is off the scale, pH 8.4+ and alkalinity 240+. No idea what the calcium is.

Affinity water says calcium is 145mg/l, total hardness 362.

I add 150g of pH minus into the fresh water and it’s still barely enough to bring the pH into range. Not sure if I should be doing anything else.

b0rn2sk8 · 6 Aug 2021 at 01:03

The PH- will be fighting a losing battle against the hardness/calcium and is only really a temporary fix. You have the same issue in fish tanks.

You could mix in RO to dilute the calcium but your well into PITA range that this point.

dale1uk · 6 Aug 2021 at 07:17

Those mains water pH and alkalinity levels are what you want to be concerned about, not the calcium levels. The high alkalinity is your main issue as it is buffering the pH too much, making it harder to adjust. Slug dosing it with acid will help lower the alkalinity along with the pH. Again, if you keep either, or ideally both your pH and alkalinity levels at the lower end of your normal readings then you'll be absolutely fine.

One other thing to point out is that it's actually recommended to keep your water balance ever so slightly on the positive side of the scale as a very light coating of calcium acts as a layer of protection to the metals within the system. If your water then goes to the negative/corrosive side of the scale then instead of attacking the metals it will attack that light coating.