Newbie soliciting comments on his spa management regime October 2017

Teaboy

Member
Oct 10, 2017
6
Ipswich, UK
Hi, - Hello everyone! - this is my first posting.

We’ve had a Hotspring Limelight Flair hot-tub (1173 litres) for four years. I'd love to see comments from experienced spa users about my home brewed spa management.

We live in an area with very hard water – the local water company says it’s 471ppm calcium carbonate, or 188.4ppm Calcium or 32.782 Degrees Clark or 47.1Degrees French or 26.753Degrees German or 4.71mol/litre. Who’d have thought there were so many ways to measure hardness!
When I measure the hardness at home using a Palintest hardness kit (add tablets one by one into 50ml of water, waiting for each to fully dissolve, until solution turns from red to blue) I have to use 12 tablets. Their instructions say that hardness (in ppm of calcium carbonate) = ((No. of tablets x 40)-20)
So for 12 tablets, that means the hardness is (12 x 40)-20 = 460ppm calcium carbonate which agrees with the water company’s data.

Although we use a water softener for all household water apart from the drinking water taps, the spa instruction manual says not to use artificially softened water. Well, after a couple of fills we noticed fragments of scale in the bottom of the tub, a sure sign that the plumbing was scaling up.
So we now fill with 80% softened water (less than 20ppm calcium carbonate) and 20% hard water. So the water in the freshly filled tub has a hardness of about 100ppm calcium carbonate.
As for other water tests, we originally used test strips – but found them to be difficult to read precisely. First I bought a really cheap pH meter from eBay, but found that it too was unreliable. At that time I worked in a scientific establishment and so could get the pH of my spa water measured very precisely by very expensive equipment, and then measure the same sample with my cheapo pH meter. The eBay meter was worse than test strips!
Next I bought a Scuba 2 water analyser. I still use it and find it very reliable – it’s readings agree closely with measurements made in my workplace, and also with measurements made using the test gear in our local public swimming pool (I have friends in high places!). It has a couple of flaws:

It has nothing on the display to indicate low battery, and will, on occasion just switch off in mid measurement.
It can’t measure much above 6 or 7ppm Cl so you can’t use it to measure Cl during superchlorination.

but I still think it’s performance per pound (or dollar or euro) is the best.

Regarding sanitation, when we first got the spa, we used dichlor, and changed the water when the CYA level got above 180ppm.
Given that CYA (as I understand it) is to prevent the chlorine being degraded by UV light, I wondered if I could get away with using unstabilised sanitiser, because the spa is covered, and mainly used in the evenings - the water is never exposed to daylight and never to direct sunlight. So we now use Fi-Chlor Superfast granules (stabiliser free chlorine) which are Calcium Hypochlorite and noted from the supplier’s website that 1.3g of granules per 1000litres of water will raise the chlorine concentration by 1ppm.
Of course, instead of having to deal with an increasing level of CYA as time goes by (if using stabilised sanitiser) I have to deal with the added Calcium from the Calcium hypochlorite. I don’t have enough experience with managing this – and I think even if I used regular dichlor I’d find the total hardness of the water would slowly increase due to the soft water leaching the scale from the spa plumbing as a result of a couple of years of using the hard water supply. I can say that since using Calcium Hypochlorite, scale fragments in the spa are becoming less of a problem.

As far as TA and pH is concerned – the TA after a refill is very high (450ppm or thereabouts). So initially I focus on getting that below 150ppm using (quite a lot of) sodium hydrogen sulfate (aka dry acid or sodium bisulphate). Once TA is around 120-150, I try to get it down to around 100 by reducing pH to about 7.0 and then aerating, although if my patience wears thin sometimes I also add a little more sodium hydrogen sulfate.

I also have an ozone injector and a silver ion thing in the filter.

I run the spa at 37°C.

I add 15ml of ‘scale inhibitor’ once a week

I shock treat either with 13g of non-chlorine shock or a high dose of FiChlor granules. To calculate the precise dose I calculate the difference between Total Chlorine and Free Chlorine and add FiChlor at the rate of 15g per 1ppm difference between Total Chlorine and Free Chlorine. I usually clean the cover, wipe the cushions and shell once a week, and also wash the filter. I shock treat if the difference between Total Chlorine and Free Chlorine is greater than 1 ppm, although if I’m too busy/lazy, I’ll just add 13g of non-chlorine shock without making any measurement.

We have a healthy population of slugs and snails in our garden and at night they seemed to like going up the sides of the hot tub leaving unsightly trails. to cure this, I put a strip of self adhesive copper tape right round the base of the hot tub (about a foot from ground level. The tape is available in garden centres - it's intended use is for putting around plant pots to prevent slugs and snails from getting to the plants. It works a treat and surprisingly, they seem to 'know' it's up there. I expected to see their slimy trails going up to the copper and then down again - but the sides of the hot tub are now completely free of slug slime, even below the copper tape.

In the summer months I use the ‘summertime’ feature of the spa – though not for the purpose intended by the manufacturer. I activate it so that it enters summertime mode at 5pm. This shuts down the circulation pump and heater from 5pm until 1am (8 hours). Here in the UK it’s possible to have your electricity supplied on a tariff that gives very cheap electricity between midnight and 7am (Greenwich mean time). This is 1am-8am British Summer Time. I also have a solar panel array which supplies us with “free” domestic hot water in the summer months, but has enough capacity to power the hot tub too. So by engaging the summertime feature AND setting the temperature to 39°C, by 5pm the water is at 39°C (thank you sun!) – so I don’t have to use ‘expensive’ electricity to heat the spa between 5pm and 1am. The reason for setting the temperature to 39°C is to make the spa comfortable in the evening between 8pm and 11pm when summertime mode is on, and so the heater is off and the spa is slowly cooling down until 1am when it starts heating up using 'cheap rate' electricity.

Comments on my regime, and how I could improve it would be most welcome.
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
48,972
Tallahassee, FL
I have a link for you that may help:

How do I use Chlorine in my Spa (or pool)?)

This will stop the addition of anything to your water that it does not need.

Your system of saving $$ on the power bill is a good one. I bet it took some fine tuning to get just the right amount of time for heating dialed in. Good job!

Let us know what you think after you look at the link.

Kim:kim:
 

pooldv

TFP Expert
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LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
Welcome to TFP!

You've learned a lot on your own and are on the right track in most cases. We recommend a CH level of 125 ppm to prevent foaming in the tub, 100 is probably close enough if foaming isn't an issue. Lowering TA to 50 will help to slow pH rise. Keep pH between 7.2 and 7.8, which will also help to prevent scale formation, even if CH is 450 ppm or higher.

Ivebeen using the procession linked in my tub for many years now and it works great. Don't skip the borates or the CYA, both make a big difference in improving the tub maintenance and experience.
 

pooldv

TFP Expert
Platinum Supporter
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Aug 10, 2012
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That is an old version that isn't updated anymore. Best to use PoolMath here on TFP , link at top of every page.
 

Teaboy

Member
Oct 10, 2017
6
Ipswich, UK
"Your system of saving $$ on the power bill is a good one. I bet it took some fine tuning to get just the right amount of time for heating dialed in."
Kim:kim:[/QUOTE]

Thanks for your helpful link Kim. I'm afraid there was no fine tuning - the Limelight "Sumertime" mode kills the heater and circulation pump for 8 hours, and the 8 hours begins when you enable summertime mod It's a fairly crude system - and if there's a power outage the summertime mode is reset to 'off' upon reinstatement of the power.
 
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