Oh No! I've ended up with too much CYA

[Mik]

Hi Guys,

Just when things were going well with my water balance, it seems I have added too much CYA. I had been working the level up from 30 but it seems that my CYA level increased until almost 10 days after the last time I added it. I do find the Taylor CA test difficult. If I do the test on a very sunny day, I can just make out the dot at 90. On a less bright day, the test seems to indicate more like 100. I am going to call it 90. Here are my full results:

FC - 6.2
CC- 0.2
TA - 90
CH - 250
CYA - 90
Borates - 50

My question is, will it do any harm to leave the CYA level where it is and just run the chlorine level a little higher? What should I aim for? ~8.0PPM?

We are almost at the end of the season in Sydney and I figure my next summer the CYA will have probably fallen into range with a few back washed over the winter? Or should I get it back into range now?

 

[Divin Dave]

HI Mik,
it wont hurt to run CYA at 90, but if something goes wrong and you get algae, then man, it is gonna take a LOT of chlorine to resolve it.
Im sure it will dilute some over winter with rain and backwashing.

here is the chlorine/cya chart. Target FC 10, minimum 7.
http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

Hi Guys,

Just when things were going well with my water balance, it seems I have added too much CYA. I had been working the level up from 30 but it seems that my CYA level increased until almost 10 days after the last time I added it. I do find the Taylor CA test difficult. If I do the test on a very sunny day, I can just make out the dot at 90. On a less bright day, the test seems to indicate more like 100. I am going to call it 90. Here are my full results:

FC - 6.2
CC- 0.2
TA - 90
CH - 250
CYA - 90
Borates - 50

My question is, will it do any harm to leave the CYA level where it is and just run the chlorine level a little higher? What should I aim for? ~8.0PPM?

We are almost at the end of the season in Sydney and I figure my next summer the CYA will have probably fallen into range with a few back washed over the winter? Or should I get it back into range now?

 

[pwrstrk]

I would target at least 9-10 and don't let it fall below 7.
Since your near the end of the season you could leave the CYA level where it's at. Your call. Just keep the FC in range so you don't have a algae bloom.

 

[tim5055]

My question is, will it do any harm to leave the CYA level where it is and just run the chlorine level a little higher? What should I aim for? ~8.0PPM?

We are almost at the end of the season in Sydney and I figure my next summer the CYA will have probably fallen into range with a few back washed over the winter? Or should I get it back into range now?

You can live with it, but MUST stay on top of the FC level. Shoot for 9 or 10 and never let it drop.

I did that for the better part of a year while mine slowly lowered for rain pump outs.

 

[Mik]

Thanks for all the help guys.

I will bump up the SWG a little more and aim for 9-10.

Presumably if we do happen to get a warm day, the pool will be safe for swimming up to say 10?

 

[pwrstrk]

Yep. You can swim in FC levels up to shock level for the CYA level. You'll be nowhere near that level.

 

[JasonLion]

Yes, as long as CYA really is 90, the FC at 10 is just fine for swimming, and anything up to roughly FC of 30 is acceptable.

 

[Mik]

Yes, as long as CYA really is 90, the FC at 10 is just fine for swimming, and anything up to roughly FC of 30 is acceptable.

As long as it really is 90 is a key question. Like I said above, in VERY bright sun, I can JUST make out the dot after staring at it for a few seconds but I need to hold the tube above waste height. In less bright light, the dot is gone at 100. I'm not all that confident with the CYA test but based on what I have read, I reckon 90 is probably about right.

 

[tim5055]

As long as it really is 90 is a key question. Like I said above, in VERY bright sun, I can JUST make out the dot after staring at it for a few seconds but I need to hold the tube above waste height. In less bright light, the dot is gone at 100. I'm not all that confident with the CYA test but based on what I have read, I reckon 90 is probably about right.

As 100 is the limit of the CYA test, so you can always try a diluted test. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1...................1................................2
....1...................2................................3
....1...................4................................5