chlorine testing with high-end cya

[rig2]

After a few partial drain and refills, I finally got my cya to 50. Since my pool is in direct sun for a solid 9 hours in the summer, I should keep my cya here or higher according to pool school. It says 60 or 70 for full sun but I think I'll start at 50 since its easier to raise cya than lower. My question has to do with daily chlorine testing.

On the chlorine/cya chart for cya in the 50 range I will need a min of 4fc and a target of 6fc. With a target of 6fc that makes the daily testing with the chlorine/pH (oto) kinda useless since it only goes to a tc of 5. So am I correct in that my daily chlorine testing will have to be a fas/dpd chlorine drop test? There is no problem with that but I think that is my only way to see if I am on target chlorine daily. Or is there a way to do a higher chlorine test with the oto? The pH part doesn't matter since I have a legit pH meter from previous hobbie with a ton of calibration fluid.
Thanks for the help and suggestions.

 

[pwrstrk]

I would get the FAS/DPD chlorine test. If you ever have to SLAM your pool it's the only way to test FC levels above 5. You already seem to know this so I'm just confirming for you. So yes the FAS/ DPD test is the only way to accurately test a above 5. What test kit are you using now ?
For your target FC level at 50 ppm CYA, I would go with what Pool Math suggests and that would be a target of 8 and never let it fall below 4. That range I would use during the swim season when the sun is the strongest and the water temp is the highest. The reason I suggest this range is it gives you more wiggle room so you don't fall below your min of 4. With the target FC of 6 that's only 2 ppm before your at your min of 4.
This is how I operate my pool as I have kids, their friends and the pool sees a lot of use. My CYA level is 40 so I target 7 and never below 3. Pool gets a good 10 -12 hrs of sun. It's an insurance policy if you will, so I don't fall below my min FC level. I've never had an algae outbreak maintaining it this way and SLAMing the pool isn't something I want to add to my to do list. If ya know what I mean.
Keep your CYA level at 50. Like you said its easy to raise if need be. PITA to lower.

 

[MarianParoo]

Sounds like a great plan!

 

[rig2]

Thanks pwrstrk. I do have the tft-100 testkit and am getting very familiar with it. It is this test kit that led me to my chlorine testing questions. So much information on the water in only 5 minutes of testing.
You totally answered this question and my next question. My next was going to be about the small chlorine window in pool school and the wider pool math chlorine window. I will go with your suggestion of an fc of 8 and a 50 cya since your pool size and usage seems close to mine. As soon as the kids in the 'hood got wind of our pool, all the sudden it became the community pool. High usage.
Word up on not wanting to slam due to algae. I want to get away from algae like I am getting away from the poolstore and poolstore schooling.
Thanks again

 

[pwrstrk]

No problem ! Glad to help you out !

 

[Richard320]

I missed the chance in your earlier thread, so...

Welcome!

It's the off-season now, so chlorine usage will be low. However, once things warm up and the pool starts getting used, you'll quickly learn your pool's appetite. Within a couple weeks, you should be able to predict your test results with amazing accuracy before the first drop of reagent leaves the bottle. Which means, simply, that you will probably get to the point where you just dump X amount of bleach in every day and test FC every other day. Since you have the OTO drops in your TF100, get in the habit of using them alongside the FAS-DPD test, so you can learn what it looks like at certain FC levels. I discovered that anything between 4 and 7 looks the same to me. But since 4 is the minimum, as long as it is at least that dark, I can probably get by just dumping in the usual amount of beach in that day.

Since you seem to be on the ball, do some comparison shopping for your bleach source and find the best value for percent-ounce. For me, it's HASA 12.5% in returnable jugs. http://www.hasapool.com/dealer_locator_hasa.php

 

[pwrstrk]

+ 1 to Richards comment on learning your pools appetite for chlorine usage. I've gone a week without testing FC by just adding the usual amount of bleach daily. This is AFTER learning my pools appetite for chlorine.
Keeping a log of all your test results and how much of what you've added is a good way to see trends in your water chemistry. Also keep in the log what the weather was like that day and water temp.