It could totally be my confusion about those two.I’ve not heard of interference from CyA before. Interesting. CyA interference for ORP is well known but I’m not sure that mechanism applies to photometer.
Localised itching on back - from the jets?
- Thread starter HottubTim
- Start date
- Feb 6, 2015
- 7,807
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
How old is your PoolLab 2?
Might be a good idea to test it against a standard to be sure it's correctly calibrated.
If your CYA is actually 50, you are safe to have the FC at 20 (SLAM level for CYA 50).
You should be testing and dosing FC prior to entering the water. And also dose after use, along with regular daily (or every other day) testing/dosing.
It is also beneficial to leave the cover open whnj the sun is out to allow the CC's to burn off.
Might be a good idea to test it against a standard to be sure it's correctly calibrated.
If your CYA is actually 50, you are safe to have the FC at 20 (SLAM level for CYA 50).
You should be testing and dosing FC prior to entering the water. And also dose after use, along with regular daily (or every other day) testing/dosing.
It is also beneficial to leave the cover open whnj the sun is out to allow the CC's to burn off.
The Pool Lab 2 is about 6 weeks old, I don't think there is a problem with it, when compared to the Hotspring test strip and the Aqucheck test strip (yes I know how unreliable test strips are) then all 3 match up for FC levels, not the best comparison I admit but good enough for now.
I am coming to the conclusion that my CL dosing processes need adjusting and FC levels have not necessarily been where they should be, 3ppm is not good enough at 50 CYA so that will now change to 10ppm dosing and not letting it fall below 6ppm. I have been testing twice a day and maintaining FC to 3ppm minimum, but not checking prior to a soak but dosing afterwards, so who knows what the levels are/were at soak time - this could well be the fundamental issue!
However this may all be moot as I am due to purge, drain and refill in a few days, I won't slam now but will keep FC high until I do purge and drain. I'll then start fresh with a 20-30 CYA level and go from there (assuming the tester and dichlor CYA calculations approximately match then I could assume that the tester is not at fault).
For anyone else reading this who has a new hottub delivered, double check the levels BEFORE starting to make any adjustments. The hottub delivery guys poured in too much salt which meant I had to drain 50% at the beginning, they also threw in enough dichlor to meet 10ppm, no measurements were taken by them (or me) at the time. So it wasn't until I had started to add dichlor myself (probably no more than 100 grammes overall) did I check CYA and by then it was 50ppm after the initial 50% drain to correct salt levels. I hadn't realised so little dichlor is needed to bring CYA levels up so quickly.
The above assumes no fault with the Pool Lab 2 tester of course.
The above assumes no fault with the Pool Lab 2 tester of course.
Well this is not a bad deal if you are in the US, you can purchase the reference kit, test the machine and then return the kit for a refund. Not sure about the UK, maybe there will be a dealer/service centre with a reference kit that I can use to verify the tester.
Check-Standard kit (3 × POL2Sp-kv) with check standards for ZERO Chlorine LR Chlorine HR/pH/TA/CYA Tot. Hardness
Validate your pool testing accuracy with the Check Standard Kit 3 POL2Sp-KV. Essential for reliable chlorine, pH, and hardness tests.
www.poolwaterlab.us
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Haha, I wouldn't put it past the Vikings to have invented the back scratcher after getting out of those Scandinavian spa's
- Feb 6, 2015
- 7,807
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Chances are if the PoolLab is matching test strips that the PoolLab accuracy is suspect as well. Test strips are unreliable. The comparison you are relying on is actually that all 3 are close, not actually accurate.
I get itchy back from bromine spas, and it is related to the jets. Enough to drive you nuts.
Try using the tub without the jets and see if you react.
Try using the tub without the jets and see if you react.
I *think* I may have reached a conclusion on this itching business. It was a rash limited to my back areas that are in contact with the high pressure water from the jets, it's almost cleared up now, I purged, drained and re-balanced the water. It's probably because of the combination the tub being filthy from the factory, Free Chlorine not enough according to Chlorine/CYA level and a Chlorine demand so high it could never reach breakpoint even at 10ppm (it really needed a SLAM to sort that one) but without getting it clean in the first place then it's a losing battle. The jets just must have been peppering my skin with bacteria with the force of water/air. CC's are now reading below 0.2ppm 36 hours after the last soak with a shock dose of chlorine after soak and the SWG running.
I purged with Ahhsome which lives up to its name this is the biofilm gunk that came out, the tub was manufactured in January and fired up in April, so this is 3 months of storage, then travelling across the pond to get to blighty, the factory test water must be awful:
I purged with Ahhsome which lives up to its name this is the biofilm gunk that came out, the tub was manufactured in January and fired up in April, so this is 3 months of storage, then travelling across the pond to get to blighty, the factory test water must be awful:
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@HottubTim Noticed your mention of the PoolLab 2 and thought I would add that my Taylor test kit and the PoolLab 2 pretty much always agree especially on CYA - with the exception of FC above 5. Once you get above 5 FC the results become unreliable and the PoolLab does not show the OR (over-range) warning that most of the other tests do. Even with dilution it will be difficult to test against your target FC of 6-8.
Just to check, are you using the standard DPD no1/no3? Or are you using the High Reading test - PoolLab Chlorine High Reading Pack (50 x Chlorine HR (KI) + Acidifying GP Powder Pillow) (which also needs a more recent firmware update)
Just to check, are you using the standard DPD no1/no3? Or are you using the High Reading test - PoolLab Chlorine High Reading Pack (50 x Chlorine HR (KI) + Acidifying GP Powder Pillow) (which also needs a more recent firmware update)
Thanks for highlighting, yes I am using the low range DPD1 and DPD3, I get OR on with DPD1 if the level is over 6, I have diluted 50% with tap water so that I can get a better estimate and it does provide a reading, however it will be worth picking up the high range for Chlorine when I put in an order for CH and phosphate, I am on the latest firmware.
Good to know it's not far off the Taylor kit, all my testing so far has been consistent and seems to reflect what's going on. It will probably be also worth getting the device calibrated when the opportunity presents.
I've been ordering from these guys who are a lot cheaper than HHT: PoolLab Chlorine HR KI Photometer Powder Pillows
Yes testallwater is a better option, have used them plenty of times but couldn't remember the site name.
The time taken to crush the tablet and start the measurement is the biggest influencer of results at high FC, the longer you take the worse the accuracy.
The time taken to crush the tablet and start the measurement is the biggest influencer of results at high FC, the longer you take the worse the accuracy.