TFP FC Targets seem high compared to other references

[runboy]

Why is it that TFPs FC Targets seem high compared to other references? I have seen other recommendations saying to keep FC levels at 7.5% of CYA levels.
With my CYA of 50% that would mean a target of 3.75PPM, but TFP recommends 6-8PPM. Also, if I bring a sample of my Pool water into Leslies @ 7 PPM, they claim my levels are too high.

 

[Jhsparky82]

The pool industry recommends lower FC levels than TFP, but they also recommend weekly shocking and ignore the FC/CYA relationship by and large. I can tell you there isn't any mixing of the methods. I figure I can keep my FC higher than "recommended" all the time, or let it drop all week and boost it high for a couple days. I know which one algae would like.

 

[mknauss]

Welcome to the forum! :handshake:

If you would like to get in Deep with the chemistry behind TFPC, see Chem Geek's Pool Water Chemistry thread

I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.

You may also want to get the Pool Math app.

 

[jblizzle]

7.5% is the minimum FC it should ever be.
So, you have to target higher each day so it does not drop below the minimum by the next time you test and add chlorine.

Do yourself a favor and stop letting the pool store test your water.
Invest in one of the Recommended Test Kits.

Please add your pool details to your signature as described HERE as it will help us help you.

 

[tim5055]

Why is it that TFPs FC Targets seem high compared to other references? I have seen other recommendations saying to keep FC levels at 7.5% of CYA levels.
With my CYA of 50% that would mean a target of 3.75PPM, but TFP recommends 6-8PPM. Also, if I bring a sample of my Pool water into Leslies @ 7 PPM, they claim my levels are too high.

The "minimum" column on the [FC/CYA][/FC/CYA] is 7.5% of CYA. So yes, for your CYA of 50ppm (it's not a %) 3.75ppm is the minimum (we round that up to 4). We recommend a target of 6 - 8 so that during the day with loss to the UV rays of the sun your FC never goes below the minimum of 4.

As to what Leslie's says, I recommend you never go there. For that matter, any pool store. We find that many times pool store employees primary goal is to sell stuff, not necessarily get your pool in perfect condition. As to whether that is because of improper training, lack of knowledge or just to sell stuff I will leave up to you. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their advice and testing.

To know what is going on with your pool we need accurate test results we can trust, and those don't come from a pool store. We base our pool care system on your personal accurate testing and only adding what the pool needs, when it needs it. To do that you need your own accurate test kit. Do you have one?

As Jhsparky82 points out, the pool industry refuses to recognize the connection between CYA/Stabilizer and the ability of chlorine to do it's thing sanitizing the water. Others here can give you the scientific details if you want, but lets just say CYA locks the ability of chlorine to sanitize. They recommend FC 2 - 4 or 3 - 5 no matter how high your CYA is. CYA gets high and inhibits the ability of chlorine to sanitize the water, they have potions to sell to you to get rid of the green.

 

[runboy]

Thank you for the answers. I do have a K2006 Test kit and have read the TFP School book. Was just wondering why every other source seems to suggest lower numbers.

 

[tomfrh]

7.5% corresponds to TfP minimums. If you keep your levels at or above 7.5% you’ll almost certainly be fine. The target numbers include additional safety factor.

I keep it above the minimum. I don’t bother with the targets.

in my experience with my pools and observing others peoples pools, the traditional numbers are too low. People get algae etc. look at all the algaecide in the pool shops. When I was a boy I recall my grandpa was fastidious with maintaining the correct numbers, but he went mad fighting algae.

 

[skimmerswimmer]

Thank you for the answers. I do have a K2006 Test kit and have read the TFP School book. Was just wondering why every other source seems to suggest lower numbers.

Most pool stores, like Leslie's for example, are still using "old school" chemistry standards for their recommended FC range. These levels are typically in line with "old school" public pool FC levels, which are for use without CYA since CYA is not allowed in many local jurisdictions. This is based on many decades old standards which have been scientifically proven to be inadequate for use in residential situations. Chem Geek's posts and information have all of the chemistry and testing behind the methods used here and elsewhere based on a simple FC/CYA relationship table. Eventually, you will see the pool industry and public pools revise their thinking as more and more people begin to wake up to reality.

TFP water chemistry methods are based on solid science. Decades-old pool industry methods are based on myth and hand-me-down practices...most of which has been debunked by scientific testing. Pool stores make a great deal of money selling overpriced magic potions to unsuspecting customers...a disgusting practice since the pool store is the root cause of the problem...low recommended FC levels (1-4 ppm) and ignoring high CYA levels.