Help Finding the FC Eating Monster

[bobandsherry]

First of all, ADMIRABLE JOB on the record keeping and charts!

Since there seems to perhaps be a correlation with the rain, I wonder if something is happening in the environment that causes a buildup on the screen enclosure. Then the rain washes it suddenly into the pool at a rate high enough to overwhelm the chlorine level.

Is it possible an increase, change of turbulence or wind direction combined with splattering caused by the rain in the retention pond allows whatever is in it (probably lots of nasties in there) to become airborne.

Interesting mystery...

Interesting indeed!

I had considered there may be something on the screen, but visual check and it looks to be pretty clean. A bit foggy this morning, but here's what it looks like today.

And as it rains almost every day or other day, I don't see how anything could build up. But obviously there is something at work here so not ruling anything out.

The retention pond is 15-20 ft away from the pool enclosure so given that distance I don't think that would be possible. Winds will generally never blow from the pond towards the pool, more typical is a cross wind.

I'll keep on looking for other possibilities. Thanks!

 

[bobandsherry]

While I love me some SWG they do not "raise" your FC level well, you need to do that with liquid chlorine... If I see my FC low I immediately add chlorine to get it up then adjust my SWG to a higher level... you can get 2.5 gallon 12% where your at, I wish I could

Yep, I get that. But I've been testing daily, most days in AM and PM and never seen my FC drop below the minimum level, it never dropped below 10FC. Bath load has been low, just me and my wife. No dogs, kids or large parties in this time. So all was good until it wasn't

From what you have posted it looks like a couple things are happening that starts a slight algae bloom..

1. it rains and lowers your CYA and FC
2. The sun comes out and eats your FC because of lower CYA
3. your keeping your CYA low, you thought it was 60, really 40, and you should have it at 80 or 90..

Recomendation

SLAM until you pass all 3, should only take a day or 2

once complete, raise your CYA to 90 and keep between 80 and 90.. because of the rain where you live you may have to test and add monthly
start by running your pump 10 hours a day at 30% and see what that gives you... I keep my FC between 6 and 10, yes it uses more chlorine/SWG but I do not care, my pool has been clear for 3 years running it this way...

Hope this helps

I'm on the SLAM path now, based on previous SLAM's agree it will only take a few days. I'll raise my CYA and now with clear eyes I'll have a better view of that dot and what CYA level is. I'm OK with keeping my FC in the 6-10 range as well.

Thanks

 

[bobandsherry]

possibly something in your pipes and/or water features? i've never used it but might you try the Ahh-some product? Have you removed your light fixture to look in the niche? other possible hiding places you have to look behind? just wild guesses.

i forgot to add that Winnie might be on to something too. As a general practice, might be worth a try to add an extra dose of liquid chlorine after a heavy rain.

You know, I've looked at the light and don't see how it comes out. But I have taken the hose and blasted water into the niche and had nothing visible show. Next time pool guy is here I'll have to ask him to show me how to remove that sucker.

I have been thinking it could be in the pipe/water features. But then I shouldn't pass the OCLT, right? And my FC wouldn't hold steady once I passed OCLT. So I've given up on that for now, but as I can't visually see those it's in the back of my mind that some really ugly lurking in there I have removed the return eyeball and pushed in a wire hanger to see if anything dislodged, but saw nothing. I've been keeping my water features running all the time now just to ensure nothing was to build up there. A little hit on my pH, but easy enough to add a few ounces of MA a couple times a week to keep that in check.

Going to finish slam, then going to follow route that CowboyCasey suggested. I'd hate to use Ahh-some as I don't know what chemicals it has, but as a last resort it may be worth using it just to rule

Thanks for taking the time to make suggestions.

 

[Spa Owner]

Roger that. I've run through cloudy pool, but not seeing it this time (which is why I posted so many pictures). Nothing visible to my eye, and with new IOL lens I'm seeing even clearer than before


After last slam the pool was running very well, SWG was set at 30% and was holding for a couple of weeks at that level, minimal changes in the FC level day over day. It rained then, and being in FL it will rain about every day for a brief period in the afternoon.


As I'm already on the SLAM path I will continue the course and keep clear of any noticeable bloom. First time I'm reading about interference with the reagents, so intrigued. What have you seen cause that before?

Thanks for taking the time to provide your suggestions.

I have seen interference with other waters with reagents...start working in geothermal water and the rule book meets windows as they go flying.

I had a think about this last night...I think I have a test to prove if there is indeed a chlorine depletion or a possible reagent issue.

Looking at the data I think its safe to assume the records are fastidious.

I am hoping your testing includes combined chlorines or total combined chlorine. The difference is the first is combined alone the second test includes free available chlorine.

Numerically if the chlorine is being used by some contaminant it would be reasonable to expect to see something like:

FAC TCC
3.0 3.5
2.5 4.0
2.0 4.5
etc

I was wondering if the records are available they may be plotted so we can see total to free ratio? I expect to see increase prior to the backwash then a reduction in gap and if the gap holds more or less steady then it most likely indicates the chlorine is not being eaten. If the gap widens significantly and I mean significantly over 20% then it is likely the chlorine is being reduced by something.

Not completely definitive, however better than a poke in the eye with a blunt stick.

 

[bobandsherry]

I have seen interference with other waters with reagents...start working in geothermal water and the rule book meets windows as they go flying.

I had a think about this last night...I think I have a test to prove if there is indeed a chlorine depletion or a possible reagent issue.

Looking at the data I think its safe to assume the records are fastidious.

I am hoping your testing includes combined chlorines or total combined chlorine. The difference is the first is combined alone the second test includes free available chlorine.

Numerically if the chlorine is being used by some contaminant it would be reasonable to expect to see something like:

FAC TCC
3.0 3.5
2.5 4.0
2.0 4.5
etc

I was wondering if the records are available they may be plotted so we can see total to free ratio? I expect to see increase prior to the backwash then a reduction in gap and if the gap holds more or less steady then it most likely indicates the chlorine is not being eaten. If the gap widens significantly and I mean significantly over 20% then it is likely the chlorine is being reduced by something.

Not completely definitive, however better than a poke in the eye with a blunt stick.

Yep, I keep track of CC but not as diligently. In the 2 years I've had the pool the CC has never been above the 0.5 and is usually just a trace or 0. So since I rarely find a CC to record I don't always test. Out of the 27 recorded readings for FC I have 27 recorded readings for CC, so it's still a pretty good representation. Typically the only time I find CC is in the early AM test, all burns off with the daytime UV. Here's the results for the time period. If the CC was just a trace (just the very slightest of pink) I'll just note as trace and record as 0.

Appreciate you noodling on this.

 

[Spa Owner]

Yep, I keep track of CC but not as diligently. In the 2 years I've had the pool the CC has never been above the 0.5 and is usually just a trace or 0. So since I rarely find a CC to record I don't always test. Out of the 27 recorded readings for FC I have 27 recorded readings for CC, so it's still a pretty good representation. Typically the only time I find CC is in the early AM test, all burns off with the daytime UV. Here's the results for the time period. If the CC was just a trace (just the very slightest of pink) I'll just note as trace and record as 0.

Appreciate you noodling on this.

This reads as the chlorine being fine and no excessive consumption of chlorine evident from the CC differences.

I think write this off as contamination and wait for next rain event, don't react and see if a change occurs then update with more data.

 

[pookiesunshine]

.... But then I shouldn't pass the OCLT, right? ....

your early posts say you are NOT passing. maybe i missed an update in later posts that you did.

another thought after seeing your check on blocked return: do all of your return flows seem normal pressure or rates? is your filter pressure higher than normal? either of which could indicate a nasty in one of your lines. other than your coat hanger note, i dont recall anything in prior posts about it. good luck.

 

[bobandsherry]

This reads as the chlorine being fine and no excessive consumption of chlorine evident from the CC differences.

I think write this off as contamination and wait for next rain event, don't react and see if a change occurs then update with more data.

That was just another piece of the puzzle that said everything was right, except for the high daily chlorine consumption. As this is 2nd SLAM this year, and similar characteristics, I was hoping to find something obvious that I was overlooking so I could prevent a similar issue in the future. But seems that with the huge brain trust here there's nothing that is obviously evident.

SLAM results last night shows that it's all clear as drop was 1.0 FC.

7:35PM - 20.0
7:41AM - 19.0 <<<--- decrease of 1.0 (way down from 4.0 the night prior)

But I'm going to go another day as I know my OCLT can be real close to 0.0 based on prior testing. The amount of chlorine required yesterday was also way down, about 50% of the prior day's SLAM. However, based on the chlorine I added it still consumed about 10FC in the 24 hour period which I would still consider too high even at 40CYA. So one more day of babysitting the chlorine, I'll drop in Dichlor today to get a little pop in the CYA along with the chlorine boost and then see how the OCLT looks tomorrow then get my CYA up to 80.

 

[bobandsherry]

your early posts say you are NOT passing. maybe i missed an update in later posts that you did.

another thought after seeing your check on blocked return: do all of your return flows seem normal pressure or rates? is your filter pressure higher than normal? either of which could indicate a nasty in one of your lines. other than your coat hanger note, i dont recall anything in prior posts about it. good luck.

Sorry to be confusing. I was talking about prior OCLT testing, before this sudden high level of chlorine consumption. And last nights OCLT was a drop of 1.0, so if there was ugly in the piping I am thinking I wouldn't get to that level so quickly (a couple days of SLAM). But honestly if this occurs again I'm thinking there has to be something lurking inside the pipes as that's the only area I can't visually confirm no algae. Just not sure how I'd validate that or even resolve it.

All returns seem to be putting out similar pressure, the one with shortest distance to the pump is slightly higher, but the pressure is no different that what I've seen previously. Water features are appear to be balanced as well, nothing appears to be out of the ordinary. Filter pressure is normal, with pump at 2500RPM the gauge reads 4PSI.

Thanks for sharing that as it's something to keep in my back pocket to troubleshoot any future issues.

 

[Jean-ji]

I live south of you and the last two torrential afternoon rains, along with strong sun before the storms, have reduced my chlorine each day. I’ve added bleach to bring the FC up from 4 to 6 the past two mornings while keeping the SWG and pump time the same.

I had to do an early slam with a new pool this spring before I understood the importance of not letting the FC go below the target range. At the end of that slam, we also had torrential storms and I couldn’t get an accurate OCLT with the massive amount of rain we were getting. With normal weather I’ve had no problems, my numbers were holding steady until the heavy rains started again.

I hope you figure out whats causing your issues, it sounds like a real puzzler with your water looking so good.

 

[bobandsherry]

I live south of you and the last two torrential afternoon rains, along with strong sun before the storms, have reduced my chlorine each day. I’ve added bleach to bring the FC up from 4 to 6 the past two mornings while keeping the SWG and pump time the same.

I had to do an early slam with a new pool this spring before I understood the importance of not letting the FC go below the target range. At the end of that slam, we also had torrential storms and I couldn’t get an accurate OCLT with the massive amount of rain we were getting. With normal weather I’ve had no problems, my numbers were holding steady until the heavy rains started again.

I hope you figure out whats causing your issues, it sounds like a real puzzler with your water looking so good.

You know why I've been keeping an eye on my chlorine levels The heavy rain, then followed with bright sun and high heat all like to play a little game with us.... I thought I was winning, until I wasn't. But as I intentionally was keeping my chlorine level high (10+) and well above minimum. I thought I had 60CYA, so at 10+ that's above target and double the minimum. Turned out I was 40CYA so 10+ is def more than enough to prevent any breakout, or so that's what I thought. That's why I'm scratching my head. Guess I'll just get into a habit of dumping some LC into the pool after a storm. Or maybe a bag of Dichlor or Trichlor so that I get a FC and CYA boost and a drop in my pH (which I can always use), then see if that keeps me out of trouble. Appreciate the comments.

 

[CavVet]

I've learned that after heavy rain events (which are few and far between around here) i need to:
1. Add a dose of liquid chlorine/bleach
2. check CYA a day or so after rain (follow instructions of sunny day, with sun at your back...etc.)
3. Lastly, it is possible that the rain diluted my water/salt content enough that the SWG reads 'low salt' and does not produce chrlorine. Go a period of time like this and algae can bloom in no time. The low salt has caught me several times because i'm not at home while the pool is running, so i never am there to watch the SWG lights.
hope this helps!

 

[bobandsherry]

OCLT passed last night, no change in the FC from last night until this morning, yeah! Water is sparkling clear, the best I've seen it. The FC has also held almost unchanged for the 4 hours since last test, so looks like the FC eating monster is gone, once again. Increasing my CYA and will let the FC drift down a bit before turning my SWG back on. Keeping LC and a couple bags of Dichlor on hand to toss in after some heavy rains. Hopefully this keeps everything clean for the rest of the pool season.

Thanks all!

 

[Spa Owner]

if this occurs again I'm thinking there has to be something lurking inside the pipes as that's the only area I can't visually confirm no algae. Just not sure how I'd validate that or even resolve it.

At the levels you are running the chlorine at there is nothing lurking anywhere unless you have some weird chlorine resistant bug with superpowers from what I can see at the levels you are running I think without checking you're exceeding the CT on cryptosporidium.

 

[bobandsherry]

At the levels you are running the chlorine at there is nothing lurking anywhere unless you have some weird chlorine resistant bug with superpowers from what I can see at the levels you are running I think without checking you're exceeding the CT on cryptosporidium.

Know you understand why I was so lost as to how I saw such an increase in my FC consumption. As my testing shows I keep a good watch on my pool chemical levels, never saw a drop in FC anywhere near the minimum FC but the consumption just took off. Today I started with FC at 20.0, ended tonight at 17.5, so 2.5 drop for 12 hours which is pretty good considering that most of the day had bright southern exposure sun on the pool. And if OCLT holds true then I'll only be down 2.5 for the full day. That would put me back to the 30% output (where I was before the FC consumption ratcheted up) for my SWG, so back to normal. Third time this year it's occurred, def has me scratching my head. But I have a new plan of attack which may help to prevent a 4th occurrence

Appreciate your responses.

 

[bobandsherry]

Just to close out the thread, SLAM successful. Two day drop in FC without my SWG running at all has been only 3FC, although today was mostly cloudy. I'd still like to know what contaminants were in the pool and how they got there. But back to running a TFP once again.

 

[Jean-ji]

I’m slamming this morning after going from an FC of 4.5 yesterday morning to an FC of .5 this morning.

I added bleach rather than tweaking my SWG twice after torrential rains this week. The lowest my FC has been is 4.0. My water is clear, but the numbers don’t support that it will stay that way. I’m going with rain and environmental.

 

[bobandsherry]

I’m slamming this morning after going from an FC of 4.5 yesterday morning to an FC of .5 this morning.

I added bleach rather than tweaking my SWG twice after torrential rains this week. The lowest my FC has been is 4.0. My water is clear, but the numbers don’t support that it will stay that way. I’m going with rain and environmental.

Must be a rampant FC monster in Central FL near the gulf. Still at a loss what caused my issue, and sounds like you are getting a dose of whatever hit me. But what type of environmental effect could cause that type of impact?

So far my FC has stayed reasonable. My FC is still high at 14, but with SWG at 30% it has held steady. I didn't want to drop FC too much before confirming that everything looked really good. Time for me to let it drift down.

With big rains expected over next couple days for both of us it may be interesting to see if we experience heavy FC loss.

Good luck with your SLAM.

 

[Jean-ji]

I’ll be adding more chlorine to keep the SLAM going as it gets washed out with the rains. Oh well, I was feeling guilty that all I ever buy at Leslie’s is chlorine and stabilizer. The rains will likely lengthen my SLAM, we’ll see.

 

[kimkats]

What a puzzle for sure! I know your screen looks clean BUT I thought mine did too until I took a soapy brush to it and then All THAT came off my "clean" screen? I used a straw broom and dipped it into a 5 gal bucket filled with soapy water (used liquid dish soap) then rinsed it off. That is all I can think of.............Rain coming through the screen and bringing whatever is on the screen with it????

KIm