First chemical test of Spa

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Another way to look at it is like this - for every 10ppm FC added by dichlor, your CYA is increased by 9ppm.

So, if all you're doing is bumping the FC up by 2 or 3 ppm with each dichlor addition, it's going to take a while before you see it in the test.

Also, the melamine-cyanurate complex (the cloudy stuff created by the test) is soluble in water up to 20ppm. So you will see no cloudiness (turbidity) until you've reached 20ppm CYA.
 
Hmm, so it seems like the acid takes a few days to register. I had a TA reading of 100, so I put a small amount of the acid in. Tested that night and it was 75. So I didn't put any more in. Tested yesterday and it was 50, and today is 25... Probably less as only half a drop changed it to the bright red. But I haven't put any acid in for a week, and nobody has used the spa this week. So I need to get the TA up before I get into trouble. PoolMath says baking soda? Does that not fizz up the spa? And how long does it take to dissolve?

Some other numbers -
PH - 7.2
FC - 1
CC - 0.5
CH - 75
TA - 25
CYA - 0


I've already bumped the chlorine up and it should be around 4. But I haven't re-tested yet.
 
No, baking soda won't fizz up. That is odd that changes don't show up right away. I assume the pump is running while you are adding acid. Just looked back and see you are adding dry acid. I guess it is taking some time to dissolve. Well, now you know, just use Poolmath to calculate your dose and wait a couple of days.

Nice progress in your testing and maintaining your water! :thumleft:
:testkit:
 
pooldv said:
No, baking soda won't fizz up. That is odd that changes don't show up right away. I assume the pump is running while you are adding acid. Just looked back and see you are adding dry acid. I guess it is taking some time to dissolve. Well, now you know, just use Poolmath to calculate your dose and wait a couple of days.

Nice progress in your testing and maintaining your water! :thumleft:
:testkit:
Click to expand...

No it was liquid. Yes pump was going, but I also turned the jets on for 15 mins after to mix it, as I didn't want that stuff settling anywhere as its so corrosive.

I still have some PH+ left. Is it worthwhile to add that to increase the TA?
 
Well what do you know, the baking soda worked! PoolMath said to add 363g, but I only added 300g. And it's back up to 75. It was reasonably quickly after adding it that I tested, so I'll try again tonight just to be sure. But here are today's numbers. I'm now up to a total of 240g of added dichlor. So hopefully I'll be able to get a reading of CYA maybe in the next week or so.

25/4

PH - 7.3
CYA - 0
FC - 2.5
CC - 0.5
CH - 75
TA - 75

Question - How low can we go chlorine wise to keep the spa sanitised? My partner has burns on 80% of his body, and a chlorine level of 4ppm was affecting his scars and making him uncomfortable. We were using the nature2 and non chlorine shock to keep the chlorine levels down. But as we spa every few days, I'm wanting to let the chlorine levels get down as we're getting in, then dose it up after we get out. Then we would have a couple of days before using again for the chlorine levels to drop. Would this work?
 
You really need to get 30 ppm of CYA/stabilizer in there. That will significantly buffer the harshness of the chlorine and make the tub much more comfortable. You/he wouldn't even notice 4ppm of FC with CYA in the tub.

With 0 CYA you can get in it at 1 ppm and keep it at 2 ppm

Glad the baking soda works! :)
 
I'm working on it. I need around 350g of dichlor to get 30ppm of CYA. I've added 240g. There's some in there, but the reading is so low that it's not measurable on my test. There's a tiny bit of cloudiness.

I'm happy to keep increasing it slowly through dichlor before switching to bleach. The main benefit of CYA from what I have read is to stabilise chlorine to minimise it being broken down by UV light. My spa is never used throughout the day, and it has heavy covers over it to prevent any UV penetration. The covers only come off at night. So to me, it's not worth it to buy the stabiliser on its own as I already have it in the dichlor. Is there any other reason that I'm not thinking of that I would need CYA urgently? I should have a good number there in about a week max.
 

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CYA buffers the harshness of chlorine. Chlorine binds to the CYA. Our CYA is 70-80 in the pool and we swam last summer with FC between 25 and 28 while we were SLAMing the pool. Nobody even noticed the elevated chlorine level. Either way is fine, whatever works for you.
 
I am so happy you are doing great :) for a spa the CYA is not to stabilize for UV, it is to have a "buffer" meaning it keeps a reserve of chlorine and uses a little at a time.. it will not seem/feel like fc of 4.. I have my tub like this and it is great... it will be fine to keep doing what your doing, it will get there... I use a little once a month to keep the CYA at 30, like 5 grams, nothing really but it works...

I am checking in every once and awhile as I am traveling now but great work...
 
Ok, I did a CYA test again this morning, as I was curious at the numbers. Not enough to read yet, but a huge increase on what it was previously. There is a lot of cloudiness now. The top view is at the 30ppm line, and I can still see the image at the bottom. But it's getting there! Yay.


9d53b718e586a983d7ba9d216252259f.jpg



This is this mornings test. I did the high sensitivity to check the actual numbers of TA. PoolMath is suggesting that both the TA and CH should be higher? Or is it ok as it is? The PH is drifting up even without use. Should I now add borates to the spa?


25/4

PH - 7.4
FC - 2.0
CC - 0.5
CH - 75
CYA - 20 (approximation)
TA - 60 (high sensitivity test)
 
your ch is fine, no need because of fiberglass and your TA is just about perfect... see where you PH goes from here, once it gets to 7.8 drop it to 7.4.. couple more days adding cya and you should be good..

doing great :)
 
Agree TA is ok. CH is OK too unless you get any foaming with jets running. If you do get foaming then raise CH to 150. Yes, it is fine to add borates now.
 
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