Just got test kit.... whaaaaaat ?

[poolboyjohn]

Hi all,

Just received my test kit (sadly not the one you recommend as tried hard but couldn't find a way of getting one in France...) - I went for a photometer kit in which I crush down different type of little tablets and then it gives me a reading of my pool chemistry. DPD1 gives me FC, DPD3 gives me TC, etc...

Here is what I have just read, and it seems a bit strange to me...
I've done the measurement at 7pm just as the pump kicks back in for the whole night (using a SWG and was recommended to run it for the major part at night)
FC = 0.1
TC = 0.1
pH = 7.0
TA = 174
CYA = 84
Salt = 5

Apparently I should not have any CYA as my SWG runs on a REDOX sensor which is supposed to "self control" using the voltage of the water.... I'm very tempted to turn it off as I don't know/think it was worth the extra cash.
As for the pH it seems to really go all over the place... As I have an pH minus machine, it automatically reads the pH and injects small amounts of pH minus to control the pH of the pool.
Sometimes it reads 6.8, sometimes 7.4 (the max setting it will allow) and then back to 6.9, etc... even though I have not had it running at all (not put any pH minus in it). It just seems to jump all over the place.

In terms of pool problems, apart from regular brown dirt in the center of my pool (its an out of ground pool) which I thought many times was mustard algae (but it feels gritty even though it disappears when you brush it), but I'm thinking it may have just been the pollen/dirt in the air as it was really bad two weeks ago and is much better now (less pollen in the air at the moment compared to two weeks ago).

Sorry I'm a newb on this and it seems my chemistry if all over the place, part of me is wondering if my SWG (which is from 2018) really works that well...
How can I reduce the TA ?
I know the CYA is high, but with kids playing in the water, within a few weeks I'm sure I'll be dropping back down into a normal range...

Any help / advice welcome,
Best,
John.

 

[Shirker]

sadly not the one you recommend as tried hard but couldn't find a way of getting one in France..

It is unfortunate the TF kits are not shipped internationally.

Apparently I should not have any CYA as my SWG runs on a REDOX sensor which is supposed to "self control" using the voltage of the water....

I know the CYA is high, but with kids playing in the water, within a few weeks I'm sure I'll be dropping back down into a normal range

The CYA should not fluctuate unless you are adding CYA or adding water. The only good way to reduce CYA is to exchange water. But you need some CYA to help buffer the action of the chlorine and to help protect chlorine from the sun.

I have an pH minus machine, it automatically reads the pH and injects small amounts of pH minus to control the pH of the pool.
Sometimes it reads 6.8, sometimes 7.4 (the max setting it will allow) and then back to 6.9,

PH is going to be difficult to test. Does your sensor have instructions on how to calibrate?

How can I reduce the TA

You will add acid to bring PH down. That will reduce your TA. Then you will need to aerate to bring the PH back up. But without a reliable PH test, it will be difficult to do.

I recommend the Pool Math app (for Android and ios). But everything is going to be predicated on having a good test kit. I honestly don't know the solution for that...

 

[poolboyjohn]

Hi Shirker,
Thanks for your response.
As I said, I've just got a photometer system with tablets (scuba II).
I've just remeasured the FC at 0.4 now the swg has been on for a couple of hours at 80%.
Yup, for the CYA, I get that it will only drop when I gradually refill water... Not much I can do there but encourage kids to splash a lot ;-)

Regarding measuring pH I've now got a good measurement system so I'm confident with my readings.

I'm a bit worried about dropping the pH as it is already low... How do I get it to rise back up safely? Doesn't a low pH have a risk of damaging the pool/pool equipment?

To be honest since I've had the pool I've had more of an issue with low pH and having to add product to increase it rather than having to reduce it... Anything that can explain that?
Finally, how do you check a swg is doing a good job? Mine is only 2 years old and running at 80%, but after three hours running (at night time) my FC has only gone from 0.1 to 0.4... is that a normal rate or is that really slow?

 

[Shirker]

Regarding measuring pH I've now got a good measurement system so I'm confident with my readings.

I'm a bit worried about dropping the pH as it is already low... How do I get it to rise back up safely? Doesn't a low pH have a risk of damaging the pool/pool equipment?

If you are confident in your PH readings and you really are at 7 now, then aerating the water should bring the PH up just a little. Have the kids splash around. if you have a fountain or other water feature, turn that on. Once you PH rises, add acid (use the Pool Math app to determine how much) to bring your PH back down to 7. Repeat until your TA is where you want it.