CYA, FC... Max?

[colsoncj]

So I have the dreaded high CYA (about 110 ppm). Its a new to me, vinyl above ground large (20k gallon) pool. I know I need to drain/refill... and will. For now, I'm just going to be liberal in backwash/fill and take every opportunity I can to remove water and add fresh.

I know with CYA levels outside of norm it means you should have higher FC levels. Which leads me to my noob questions:
1. Why isn't this more widely communicated? Look at any strip/testkit/book, most say 1-4 ppm FC is where you want to be. Over 4ppm is bad.
2. With a CYA of 110, lets just say I should have a FC level of 10. I'd prefer to run at the min so I don't overly skew my pH readings... so lets target 8ppm. Is it high FC that's a swimmer concern, or really just high CC? Why is over 4ppm "generally" bad, and is it?
3. I have a whole 50lb pail of TriChl tabs.... I'm guessing they need to go on FB marketplace... and I need to go get some walmart bleach... right? (I think I know the answer to this...)
4. With bleach, how often do you guys test/adjust? I'm used to an inline chlorinator when i was a kid, or tabs... almost a set and forget.
5. Any other non-obvious (or maybe obvious) words of wisdom?

BTW, pool current readings as of yesterday using a Taylor K2005 (edited - was not a K2006 kit):
pH: 7.7
TA: 150
CH: 150
(balance calc gives almost 0.0)
FC was 1, added a little chlorine...
CC was 0.25
CYA is around 100 to 110.
Corrected TA is 118
Correct balance is -0.05 or so.

 

[Oly]

Dilute your CYA test sample 50% with tap water and double your results for a more accurate test of your CYA ppm. You only need to drain enough water to bring your CYA down to 50 or less.

If your chlorine stays below your target range for your CYA level much longer you will be fighting an algae outbreak as water temps rise. FC/CYA Levels

 

[colsoncj]

CYA was 121ppm per professional test prior to a few large backflush/fills that are bringing it down... Threw a couple of the 3" tabs in yesterday to bring FC up (not desirable - I know), but haven't checked today what its actually at. Will most likely shock it tomorrow to a desired level once I figure out where I want that to be...

I'd need to drain about 60% last I checked, or do a 25% drain down about 3 times to get back in line... but requires me to get an aux pump to pull that volume out and then work to get it back in.

Hence the temp plan of managing high levels, but liberal and frequent small drain/fills. But while staying in this mode of operation... brings the other questions out...

 

[Rancho Cost-a-Lotta]

1. Why isn't this more widely communicated? Look at any strip/testkit/book, most say 1-4 ppm FC is where you want to be. Over 4ppm is bad.

Outdated pool-industry standards. 2-4 ppm is ok if your CYA is 0-30 ppm. The pool-industry then pushes tablets which continue to raise CYA, requiring higher FC levels. They will recommend weekly shocking and will happily sell you algaecides and phosphate remover to clear up your green pool.

2. With a CYA of 110, lets just say I should have a FC level of 10. I'd prefer to run at the min so I don't overly skew my pH readings... so lets target 8ppm. Is it high FC that's a swimmer concern, or really just high CC? Why is over 4ppm "generally" bad, and is it?

CYA of 110 can be done, but never allow your FC to drop below minimum level. The pH test is invalid at FC levels of 10+ppm, so do your testing at the back end of dosing cycles when FC is at lower levels.

3. I have a whole 50lb pail of TriChl tabs.... I'm guessing they need to go on FB marketplace... and I need to go get some walmart bleach... right? (I think I know the answer to this...)

Keep them for vacations. They last virtually forever in a shed or garage. Stick with liquid chlorine bleach or invest in a salt water chlorine generator (SWG).

4. With bleach, how often do you guys test/adjust?

If you test daily, you'll get to know the needs of your pool (pH and FC adjustments). I still test every 2-3 days.

 

[DeanP66]

Those pucks you are putting in are INCREASING your CYA even more. Stop using them completely. You only want to use liquid chlorine, or calcium hypo to chlorinate your pool. Every other option adds CYA to the pool with the chlorine.

Don't trust those "professional test" results. Pool stores are notorious for bad test results, especially the CYA test. Use your Taylor K2006 and do the diluted test that was stated above. The test is only really accurate to 100, so if it looks higher, a diluted test can give you a ballpark range once you double the result.

If you're still at around the 120 range for CYA, a 50% drain and refill will put you right in range.

 

[colsoncj]

Outdated pool-industry standards. 2-4 ppm is ok if your CYA is 0-30 ppm. The pool-industry then pushes tablets which continue to raise CYA, requiring higher FC levels. They will recommend weekly shocking and will happily sell you algaecides and phosphate remover to clear up your green pool.

CYA of 110 can be done, but never allow your FC to drop below minimum level. The pH test is invalid at FC levels of 10+ppm, so do your testing at the back end of dosing cycles when FC is at lower levels.

Keep them for vacations. They last virtually forever in a shed or garage. Stick with liquid chlorine bleach or invest in a salt water chlorine generator (SWG).

If you test daily, you'll get to know the needs of your pool (pH and FC adjustments). I still test every 2-3 days.

Thank you... along the lines of what I was thinking, but wanted to double check. So... safe to run lets say 8-9ppm of FC (low end) and not have swimmer discomfort? I assume is the CC (or other factors) that causes discomfort, not FC.

I plan on going to liquid bleach ASAP for top offs and then only so or cal hypo for shock. Get away from stabilized stuff asap. I'll keep some of the 3" for vacations... but probably sell the fresh, unopened 50lb pail for now... can always get a small pail of 3" later if I need more.

I'll consult the CYA to FC chart and plan accordingly.

 

[colsoncj]

Those pucks you are putting in are INCREASING your CYA even more. Stop using them completely. You only want to use liquid chlorine, or calcium hypo to chlorinate your pool. Every other option adds CYA to the pool with the chlorine.

Don't trust those "professional test" results. Pool stores are notorious for bad test results, especially the CYA test. Use your Taylor K2006 and do the diluted test that was stated above. The test is only really accurate to 100, so if it looks higher, a diluted test can give you a ballpark range once you double the result.

If you're still at around the 120 range for CYA, a 50% drain and refill will put you right in range.

Thank you! Agree, plan on going away from pucks ASAP. Needed chlorine and had them, so when ahead and threw two in until I can get situated on liquid bleach.

Good to know on the pro test... They said CYA up to 200 is fine... which made me start to question everything else that came out of their mouth...

I'll do a diluted test with the Taylor K2005 (edited - was not a K2006 kit) and report back. Last time I did it, I did full strength, and it extrapolated approximately to what their reading was. But since I've drained and topped off, want a more accurate reading to start a liquid chlorine plan and target anyway.

Would love to do a 50% drain and refill... but 10k gallons is a lot, and would require me sourcing a pump to even get 50% out... Its my plan for later, but for now, wanted to figure out how to ride this out appropriately. Also hoping that enough small drain/refills will net me more than I think and see an improvement. Will know for sure in a couple days when we vacuum and top off again. Thats when I plan to retest CYA to see if I've moved the needle any. if not - start planning a lot of pump/hose time. and a massive refill

 

[Rancho Cost-a-Lotta]

So... safe to run lets say 8-9ppm of FC (low end) and not have swimmer discomfort? I assume is the CC (or other factors) that causes discomfort, not FC

Yes, assuming it's within range according to the FC/CYA chart. CC is what causes irritation.

 

[DeanP66]

I would stay away from the cal hypo as well, cause that will add calcium hardness (CH) to your pool over time. Your CH is low (150), but you have a vinyl pool, so you don't really need to add any anyway. Stick to liquid chlorine or bleach. If you get tired of having to add it every day or two, you could decide to get a SWG which makes things much easier. No lugging chlorine boxes from the store, no need to add any chlorine at all. Simply set your generator's output so that it generates the chlorine that you need. It's not cheap, but it can save you so much time and effort. Also, with a generator, you won't need any pucks for vacation cause the SWG won't know you're on vacation. It will just keep doing its job generating chlorine for your pool.

You could use a submersible pump to drain your water. I bought one like this and it's very handy to have around. You can use it with a hose, but I'd recommend you remove the hose fitting and use 1.25 PVC. It will drain way faster that way. I built a little fitting out of pvc with a nipple attached on the end and attached my vacuuming hose to it. You could also use a backwash hose with a clamp to hold it on.

Superior Pump 91330 1/3 HP Thermoplastic Submersible Utility Pump with 10-Foot - Sump Pumps - Amazon.com

Superior Pump 91330 1/3 HP Thermoplastic Submersible Utility Pump with 10-Foot - Sump Pumps - Amazon.com

www.amazon.com

 

[Newdude]

I assume is the CC (or other factors) that causes discomfort, not FC.

CCs which are the byproduct of the chlorine doing it’s thing is what cause the discomfort like itchy eyes.

Running too low of a FC based on the FC/CYA Levels will be unsanitary and allow bacteria, viruses, etc to cause a whole ‘nother set of discomfort like rashes.

Swimming is safe and unnoticeable with an FC up to slam level following the FC/CYA Levels, Which for 100 CYA is 39 FC.

 

[Rancho Cost-a-Lotta]

Before you get too far ahead of yourself, you really need to determine if you have algae. Is the water cloudy or green? You reported a CC level of .25 which is not a valid test result and you had virtually no chlorine in the pool. If you suspect algae, it would be advisable to lower your CYA prior to starting a SLAM. A SLAM with a CYA of 100+ would require an FC level of 39+.

 

[mknauss]

cal hypo for shock

 

[JJ_Tex]

So... safe to run lets say 8-9ppm of FC (low end) and not have swimmer discomfort? I assume is the CC (or other factors) that causes discomfort, not FC.

I generally keep mine in that range, sometimes a bit higher. Multiple times over the year I received compliments on how much better my water feels than a "pool with a lot of chlorine in it".

I've given up trying to explain and just meekishly tell them "thanks" or "yeah, I like it too"

 

[Newdude]

I've given up trying to explain and just meekishly tell them "thanks" or "yeah, I like it too

Yup. A quick thanks and ‘How’s your burger?’

 

[colsoncj]

Before you get too far ahead of yourself, you really need to determine if you have algae. Is the water cloudy or green? You reported a CC level of .25 which is not a valid test result and you had virtually no chlorine in the pool. If you suspect algae, it would be advisable to lower your CYA prior to starting a SLAM. A SLAM with a CYA of 100+ would require an FC level of 39+.

No algae... already got from green and murky at opening to crystal clear and no known issues other than chem balance...

Just shocked it this afternoon too to bring chlorine levels back up until i can get to the store and get some liquid bleach.

 

[colsoncj]

CCs which are the byproduct of the chlorine doing it’s thing is what cause the discomfort like itchy eyes.

Running too low of a FC based on the FC/CYA Levels will be unsanitary and allow bacteria, viruses, etc to cause a whole ‘nother set of discomfort like rashes.

Swimming is safe and unnoticeable with an FC up to slam level following the FC/CYA Levels, Which for 100 CYA is 39 FC.

Thank you... kinda what i was starting to find, but more confirmation is good.

Also was starting to dig into whether or not I wanted to run on the lower or higher side... bacteria and viruses from lower than recommended levels was something I was curious about.

 

[CraigChing]

Hey Cory! Welcome to TFP! I’ve been living with high CYA the last couple of years. I won’t promise that what I’ve done will work for you, but I basically have been doing what you’re suggesting, keeping FC around 9 ppm so I can still measure pH properly. If you want to see my numbers for the last year, click on my name and you can review my logs to see how I have been doing it.

I’m really hoping that when I open on Saturday that I may finally have reduced my CYA to a more TFP friendly level and can finally enjoy lower FC levels and really dial things in. The one thing you’ll notice in my logs is that I test very frequently and really work to keep my FC up. I highly recommend frequent testing to achieve what I’ve done. For the record, I haven’t had to SLAM yet!

 

[colsoncj]

Hey Cory! Welcome to TFP! I’ve been living with high CYA the last couple of years. I won’t promise that what I’ve done will work for you, but I basically have been doing what you’re suggesting, keeping FC around 9 ppm so I can still measure pH properly. If you want to see my numbers for the last year, click on my name and you can review my logs to see how I have been doing it.

I’m really hoping that when I open on Saturday that I may finally have reduced my CYA to a more TFP friendly level and can finally enjoy lower FC levels and really dial things in. The one thing you’ll notice in my logs is that I test very frequently and really work to keep my FC up. I highly recommend frequent testing to achieve what I’ve done. For the record, I haven’t had to SLAM yet!

Thanks for the feedback! I know I'm not the only one with this issue, and glad to see others are taking or have taken the same approach with some success.

How did you link your pool math subscription to your account? I went ahead and splurged on being a contributor to the app, and wouldn't mind sharing my logs as well.

 

[colsoncj]

OK... I think I was able to fix my pool math account to my forum account... so should be able to see my logs. (let me know please )

Next questions:
1. For testing FC and/or TC, when running a high FC like I need to, do you just dilute with 50% tap and multiply readings by 2 using the K2006? (like the high CYA testing method)
2. When using the poolmath app and logging a chemical addition (or looking at what to add via test log), and it wants a Bleach Chlorine %, do you use the % of Sod Hypo or the % available chlorine?
For example the bleach I'm looking at is 7.5% Sod Hypo but lists 7.13% available chlorine.... which would the app prefer? (not a big difference, but curious).

 

[mknauss]

You need to drain at least half of your pool volume and refill.

1 - No. Tap water has chlorine in it. You can try using distilled water, but your test error will be well over 20%.
2 - Use % sodium hypochlorite for bleach concentration.