Free Chlorine Levels - Rate of Change from Higher FC Starting Point

[br3wski3]

I saw a thread last week that I meant to refer to and ask about but can't seem to find it now - ah well

Basically, someone was asking about adding extra liquid chlorine due to being away for a bit to which someone replied about it degrading faster at higher amounts

Let's say one typically loses 2ppm FC per day, tests and bumps from 2ppm to 4ppm each morning

Note that I don't use tablets at this point as I want to avoid the trichlor CYA (having added my own CYA, 30ppm, in conjunction with on-going liquid chlorine use)

Say one might be away or otherwise not able to add liquid chlorine for a couple days (or more but simple for this example) - the question this other person was asking was basically could you bump it up to 8ppm FC where the response seemed to indicate that it would degrade faster than 2ppm per day initially at the higher amount

Is there a correlation or general idea of what this rate is and how it changes with respect to the changing level such that one might estimate how much FC to add to truly cover the number of days? Or, am I barking up the wrong tree and this isn't even something to consider/discuss? Again, preferring to avoid the tablets, if possible

 

[HermanTX]

ay one might be away or otherwise not able to add liquid chlorine for a couple days (or more but simple for this example) - the question this other person was asking was basically could you bump it up to 8ppm FC where the response seemed to indicate that it would degrade faster than 2ppm per day initially at the higher amount

In general you are correct but when we talk of high levels, think of SLAM levels. FC will decrease quicker from 20ppm than it will from 10ppm given the same environment. I have not seen a chart and I would think it would be very area specific.

When going on vacation and planning for daily loss, use your estimate for your specific pool/area. if that is 2ppm per day and you will be gone for 7 days - then 14ppm needs to be accounted for and have the final FC level still be in the target range for your CYA level. With a CYA of 30, your SLAM level is 12ppm so you are somewhat hindered by that as your ending target range is 4-6ppm. So losing 2ppm per day only allows for 3-4 days of being away. It is not recommended to add FC above the SLAM level (treating mustard algae is the only exception).
Also, if you are running at CYA 30, then bumping up to 40ppm also will help.
Others may have some additional comments.

 

[br3wski3]

In general you are correct but when we talk of high levels, think of SLAM levels. FC will decrease quicker from 20ppm than it will from 10ppm given the same environment. I have not seen a chart and I would think it would be very area specific.

When going on vacation and planning for daily loss, use your estimate for your specific pool/area. if that is 2ppm per day and you will be gone for 7 days - then 14ppm needs to be accounted for and have the final FC level still be in the target range for your CYA level. With a CYA of 30, your SLAM level is 12ppm so you are somewhat hindered by that as your ending target range is 4-6ppm. So losing 2ppm per day only allows for 3-4 days of being away. It is not recommended to add FC above the SLAM level (treating mustard algae is the only exception).
Also, if you are running at CYA 30, then bumping up to 40ppm also will help.
Others may have some additional comments.

Thank you @HermanTX really appreciate the info

 

[br3wski3]

It is not recommended to add FC above the SLAM level (treating mustard algae is the only exception).

Actually, any more detail on this? Just wasteful or are there negative consequences?