best way to raise CYA

[Zindar]

I have on hand some powdered chlorine stabizer I could use to raise my CYA. It's current at 30, but I think since I have a SWG (above ground pool), it ought to be at 70-80.

I've read on this forum that I should be putting it in a sock and hanging it from my ladder, but the instructions say to power directly into skimmer backet (but backwashing first because you can't backwash until at least 48 hours after a 24 hour cycle of running the pump.

Should I really not be following those instructions, but using a sock instead? If so, why are the instructions wrong?

Oh, and I have another question: The instruction have a chart that tells how much to add given the size of pool and how many parts I want to raise it, but the units of measurement are in pounds of powder. It's much easier for me to measure in volume. Is the density the same as water, which is one pound = one pint, or is the density different?

 

[basod]

You can measure by dry volume using the pool math calculator. It's best to add a smaller amount and retest after a week. As for application pour the powder in an old sock and tie it off in front of a return jet. Some of the powder won't dissolve so brush it around and don't backwash for a few days

 

[Richard320]

If you follow the bottle directions and need to backwash before it has all dissolved, you literally flush money down the drain. That's just fine with the sellers. More money for them. But that's why we say use the sock method. You can backwash as much as needed and you'll only lose the few ppm in the water you flushed. If the water is clear and you don't anticipate needing a backwash for a week or so, do what you please. It's your pool.

Poolmath can calculate the dose for you and give it to you by weight or volume.

 

[Donldson]

It's not that the instructions on the bottle are wrong so much as we find them to be less optimal. First, with the sock you know when all of the CYA is dissolved. If it is in your filter then you don't know if/when everything is dissolved. It is possible for the filter to have dead spots as well where the granules could collect and be flushed away on the next backwash. We are also not huge fans of doing anything that will prevent you from backwashing the filter if needed. There is also the unlikely possibility when adding solid chemicals to the skimmer that they could clog the pipe. Very unlikely but I can recall at least one time that it happened.

As for weight vs volume, it is close but not exactly same density as water. A gallon of CYA is about 7.5 lbs. PoolMath will give you numbers in both weight and volume to make things easier.

 

[Zindar]

Thank you. Wow, that pool math calculator, with it's measurements in both volume and weight is really handy. I will be using it's volume measurement. I also verified that it's weight measurements matches the chart on my bottle, so I have confidence in the accuracy of that pool math calculator.

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It's not that the instructions on the bottle are wrong so much as we find them to be less optimal. First, with the sock you know when all of the CYA is dissolved. If it is in your filter then you don't know if/when everything is dissolved. It is possible for the filter to have dead spots as well where the granules could collect and be flushed away on the next backwash. We are also not huge fans of doing anything that will prevent you from backwashing the filter if needed. There is also the unlikely possibility when adding solid chemicals to the skimmer that they could clog the pipe. Very unlikely but I can recall at least one time that it happened.

As for weight vs volume, it is close but not exactly same density as water. A gallon of CYA is about 7.5 lbs. PoolMath will give you numbers in both weight and volume to make things easier.

Oh, I replied before seeing this post. Thank you for that well reasoned description of the differences, and science behind it, of skimmer vs sock - exactly the type of reply I was hoping to see. I don't anticipate needing to backwash that soon, but I see you list other advantages of the sock than just freedom of backwashing. Taking it all into account, I think I will use the sock method.